Microtouch: 8-bit Open Source Media Device

First time accepted submitter misterbarnacles writes "The Microtouch is a mobile media device that aims to become an open-source alternative to the iPod Touch." Deeper investigation reveals that the Microtouch is a nifty little device. Powered by an 8-bit microcontroller with only 2.5K of RAM there is an example ebook reader application. A primitive application framework (for some definition of the phrase) is available as Free Software, and for the hardware hackers the EagleCAD PCB files are published under a CC attribution-share-alike license.

Comments

For a low-power 8-bit MC with 2.5k RAM...

[ohcrapitssteve]

For a low-power 8-bit MC with 2.5k RAM, the navigation seems more fluent than some Android tablets I've used...

Re:For a low-power 8-bit MC with 2.5k RAM...

[UnknowingFool]

Touch only? The article isn't clear whether it is multi-touch and whether it has accelerometers or a gyroscope.

Re:For a low-power 8-bit MC with 2.5k RAM...

[polymeris]

I think the touchscreen is single-touch only, but pressure sensitive (from the diagnostics screenshot). The article does say it has an accelerometer.

For DIY purposes, it would be cool if it had any other I/O besides USB -- e.g. ADC or just serial-- which isn't clear to me.

Re:For a low-power 8-bit MC with 2.5k RAM...

[Anonymous Coward]

When you have only 2.5k RAM, there is no operating system as such AND you are pretty much always using registers. It'll fly by comparison.

Of course it'll only ever single task reliably and SECURE 3rd party development will be a bitch. There is of course no TCP/IP stack OR networking, beyond a serial USB connector.

It is of course a cute project and takes me back a little.

Jason.

Re:For a low-power 8-bit MC with 2.5k RAM...

[TheGratefulNet]

hint: add xbee to its serial port and have another arduino (etc) on the other side with an xbee on ITS serial port.

printf and scanf (well, sort of) after that. /end hint

Re:For a low-power 8-bit MC with 2.5k RAM...

[SomePgmr]

Agreed, a spot for optional pin headers would have been nice... and it doesn't look to have that. It would've increased the utility of the device a lot. Though from rossum in the Hack A Day comments...

You can plug a SPI device into the microSD slot (there is something in the works on a .8mm pcb that does this) or if you are really stuck you can use the ISP port + overload the LED pin for device select.

Not the route I'd want to take, personally. Probably better off having your own board made if you're comfortable with smd work and want exposed points. Maybe ditch the accelerometer and do an i2c bus or something?

Re:For a low-power 8-bit MC with 2.5k RAM...

[jaseuk]

Ah cute. I like it.

Jason.

Re:For a low-power 8-bit MC with 2.5k RAM...

[Anonymous Coward]

How many languages does the navigation speak? Will it be better than Google Maps?

Re:For a low-power 8-bit MC with 2.5k RAM...

[Pence128]

The AVR is a Harvard device, the one they're using has 32k of flash. The return stack is in ram so preemptive multitasking is possible. There is indirect with displacement addressing so data can be position independent. There's no memory protection though. You could fit TCP/IP on it, probably over a communications USB class, but I don't think you could fit much more than ftp/telnet on top of it.

Re:For a low-power 8-bit MC with 2.5k RAM...

[FyRE666]

I was very impressed with the video of it in use. It must be using a secondary CPU or dedicated controller for the LCD as there's no way the little 8bit ATMega could update the LCD that smoothly on its own. I'm really looking forward to getting my hands on one of these!

Re:For a low-power 8-bit MC with 2.5k RAM...

[fatphil]

Clearly it's a smart LCD, as the device doesn't have the RAM to store a frame-buffer. The pages are of course pre-rendered, all he's doing is blitting. I hope the smart-LCD has enough video RAM, as it then might be using hardware scrolling to keep bandwidth and load down, otherwise it looks like the uC will be running at at least 50% CPU constantly, even at 5V operation.

Great work, either way. It makes the fancy-pants project I'm working on at ${DAYJOB} look like a pile of crap, comparing xistor counts.

Cool concept

[Squiddie]

Now I wonder if people will use it. Maybe if someone produced them to order instead of having to build it yourself, they would be good. Especially since it might end up being a lot cheaper than an iPod touch.

Re:Cool concept

[Beorytis]

TFA has a link to buy preassembled for $69, but it's out of stock.

8 bit audio?

[Hatta]

8-bit audio sounds like crap. Can you even decode MP3s on an 8-bit processor?

Re:8 bit audio?

[MightyMartian]

From Wikipedia

The Chinese Actions Semiconductor's audio processor family of chips (ATJ2085 and others) contains a Z80-compatible MCU together with a 24-bit dedicated DSP processor.[41] These chips are used in many MP3 and media player products.

Re:8 bit audio?

[Rockoon]

Nobody said anything about 8-bit audio, and of course you can decode MP3's on an 8-bit turing-complete machine.

Furthermore, since we are going to be talking about irrelevant crap because of the Hatta's in this world, most DAC's in digital audio players are only 1-bit.

Stop posting.

Re:8 bit audio?

[Lunix Nutcase]

You apparently didn't comprehend what you posted. The 24-bit dsp is what decodes the mp3s not the 8-bit cpu.

Re:8 bit audio?

[polymeris]

Not with this thing, at least... from TFA:

OK, it can't play MP3s, but it does have a 320x240 TFT color display [...]

There may be many cool possible DIY apps, but I wonder how this is a "media device", yet alone an iPod competitor.

Re:8 bit audio?

[Servaas]

From their website, and no it doesnt do mp3.:

Sure, the latest "iTouchy" gadgets are pretty cool. But who wants a locked down device? Why not build your own touch-screen device, with your own apps, all on open source hardware and using open source tools? OK, it can't play MP3s, but it does have a 320x240 TFT color display with resistive touch screen, an Atmega32u4 8-bit microcontroller, lithium polymer battery charger, backlight control, micro-SD slot, and a triple-axis accelerometer. Yeah, this is the next big thing and for those of us who like to DIY, you can do a lot of cool stuff with this dev board.

Re:8 bit audio?

[TheGratefulNet]

this is a control element. it does not sit on the analog audio plane. it CONTROLS things that might be analog but this is not any dsp engine. its a CONTROLLER, mate (duh!).

.

Re:8 bit audio?

[Lunix Nutcase]

*facepalm* I was talking about what the person I was responding to quoted in their post. Reading comprehension ftw!

Re:8 bit audio?

[TheGratefulNet]

1-bit is marketing speak. its about shifting the high freq above the passband (for tech reasons) and for keeping parallel (costly) interfaces down.

INSIDE its a shift register and then a dac.

1-bit is stupid marketing speak. whatever the native word length (spdif is 16/20/24 only) is, that's what the dac has to decode. '1 bit' is bullshit as it only is a transfer protocol, not a decoding method!

Re:8 bit audio?

[maxwell demon]

I take it that the stated RAM doesn't include video memory, right? Because at 320x240, even with only 1 bit per pixel you'd need 9.6KB, and that gives you no color.

Re:8 bit audio?

[Anonymous Coward]

Sorry, 1-bit is not a transfer protocol as 1-bit it is a name for a delta-sigma modulation based DAC, technically it is related to a pulse-with modulation (PWM), class-d amplifier and pulse-density modulation.

Re:8 bit audio?

[goose-incarnated]

You're going on the rather unwarranted assumption that all displays are framebuffer-backed. While I'm pretty certain such 8-bit devices exist, I've never had the pleasure of using one.

Re:8 bit audio?

[zAPPzAPP]

The person you responded you posted a viable answer as a response to the 8bit mp3 decoding question.
I don't see what you are getting off on...

Re:8 bit audio?

[khellendros1984]

Yes, if the processor implements a Turing-complete instruction set, anything that can be calculated by another computer could be calculated by *that* computer. Now, the real question is if it could be calculated at real-time speeds on that microcontroller...

Re:8 bit audio?

[wierd_w]

You've never used vga mode 0x13h?

It's an 8bit framebuffer mode, 64k in size...

Must not be very old to have NEVER played with it...

Re:8 bit audio?

[goose-incarnated]

Never on an 8bit microcontroller, no. On an 8bit graphics processor, yes (the memory was on the processor, not on the microcontroller).

However, the vga mode 13h[1] was not necessarily frame-buffer backed[2]; I used a pointer to a framebuffer at memory 0xb4000000 (I think it was this particular address, not too sure) with the full knowledge that that memory was not on the microcontroller.

However, to keep some perspective, I was referring to the PIC's, the atmels and similar microcontrollers - none of them ever had a framebuffer-based video; fb-based video (if any) was always provided by an external graphics processor.

[1] Either "0x13" or "13h", not both (redundant, see?)
[2] Perhaps I'm remembering wrong and mode 13h was not a slow-as-molasses interrupt interface to the external graphics processor. In my memory, it was a (you guessed it) slow-as-molasses interrupt interface to the external graphics processor. The Borland BGI library used the SAMIITTEGP.

Re:8 bit audio?

[maxwell demon]

A pure text mode display could not show graphics. This device does show graphics. That graphics has to be stored somewhere, and sent from there to the screen.

Re:8 bit audio?

[tibit]

I'd think that it's not a problem if the processor has single-cycle execution and a 16x16 single-cycle multiplier. You'd also need a fast clock (50+MHz).

Re:8 bit audio?

[tibit]

It probably could play MP3s as follows:
1. Tweak framework design to allow a background task.
2. Pre-render MP3s in the background and store the decoder output back onto the SD card. This may need ugly hacks like storing some tables at runtime in the built-in FLASH or EEPROM since RAM is short, but it'd work in principle -- probably at 1/10th of native speed or somesuch.
3. Play pre-rendered MP3s in the foreground.

Re:8 bit audio?

[Rockoon]

0B8000h for some video modes, 0A0000h for others.

Re:8 bit audio?

[wierd_w]

IIRC, 13h was a 64k window from the adaptor itself mapped into the adaptor rom region at A000. The memory was native to the vga adaptor and writes to it were "live" at the next vertical retrace. Calling the vertical retrace function was not explicitly needed, but helped reduce snow on garbage vga chips.

Re:8 bit audio?

[FyRE666]

Real hackers used unchained Mode X of course ;-) Mode 13h chained 4 segs together to give nice easy linear addressing, but it meant that the other 3 segments were wasted, so offscreen buffering and smooth hardware scrolling etc wasn't available.

If you're interested in that sort of hacking now, and Arduino + Gameduino shield is a good alternative, I've found ;-)

Re:8 bit audio?

[tepples]

For one thing, no physical machine is Turing complete. Turing completeness requires unbounded memory, which does not exist within this universe. I'll assume you meant LBA complete. For another, LBA completeness makes no guarantee that an algorithm will halt within a reasonable number of processing steps, which is important for something like a real-time MP3 decoder that MUST produce at least 44,100 samples within each second.

Re:8 bit audio?

[Miamicanes]

Way back in the ancient days of yore (when 2600 was a videogame system and not a magazine dedicated to hacking), there was something called a "Sprite", and its purpose was to allow you to control individual pixels of a "large" (or what passed for it in 1977) and sparse display with lots of potential pixels, and very little ram. Back then, you literally had the following graphic elements at your disposal:

* A 20 pixel "playfield" that could be doubled, mirrored, and/or stretched. The 20-pixel chunk could be stretched, duplicated, or mirrored. You could reload its definition registers between scanlines and reuse it to display different things on different rows.

* A pair of 8-pixel sprites that could also be doubled, mirrored, and/or stretched. 8 pixels wide, one pixel high. You'd set it to some horizontal offset from the left, enable it manually when the raster reached a specific scanline, then leave it on until you got to the end of the last scanline where it should be displayed. If you wanted it to look different on the next scanline, you reloaded its 8-bit register with a new value.

* Three single-pixel sprites -- two missiles, one ball. They basically consumed ~two bytes apiece... one byte for horizontal offset, and one byte for control & attributes (width, motion-delay, etc).

Just to give you an idea how crude it was, there's a reason why the score digits in Circus Atari were uneven... it used player 0 to draw digits 1 and 2, and player 1 to draw digits 3 and 4. It drew digits 1 and 3 on the odd scanlines, then reloaded the register and offset to draw digits 2 and 4 on the even scanlines. When some game I can't remember came out that had a 6-digit scoreboard, it was considered groundbreaking because it went a step further, and reused the same sprite twice on the same scanline. It used player 1 to draw digits 1, 2, 5, and 6, and player 2 to draw digits 3 and 4. It defined the sprites for digits 1 & 3 or 2 & 4, then paused a few clocks and reloaded the byte for player 1 with the data for digits 5 or 6.

The crazy thing about the 2600 is that few of its limits were truly hard. I think someone a year or two ago actually hacked a homebrew 2600 cartridge using an ARM9 microcontroller that tricked it into doing 160x384 interlaced graphics (by tickling the vertical retrace clock register at exactly the right moment to trick the TV into drawing the next field as an even interlaced field instead of just redrawing odd fields over and over again) and did insane things like simulate cartridge rom so it could rewrite itself on the fly in ways that would have been physically impossible on any cartridge of the era. From what I recall, it actually sparked a debate among the 2600 homebrew community over how far you could legitimately go stuffing modern microcontrollers into faux 2600 cartridges to act as coprocessors before you defeated the whole point of saying it was a "2600 game". I think the consensus was that it was OK to do things like the later Activision games did (incorporating shift registers and stuff into cartridges to auto-update the bank of ram seen by the 2600), but pre-rendering 26 megabytes of video kernel code into 6502 assembly to reload the registers in slightly different ways, then spooling it from a microSD card was just being kind of silly. Still, it's kind of amazing what you can pull off with the crude, primitive chips in a 2600 when you're able to offload everything from program logic to kernel code onto modern chips, and just drive the 2600's bare metal "from the outside" (so to speak).

It's sobering, in a way, when you consider that much of what modern GPU chips do is software controlled as well, and think about just how far a modern GPU could probably be pushed if Moore's Law didn't automatically mean there'd be a version that's 500MHz faster on the shelves next year. If Mars were colonized today, had a videogame industry, and a new videocard on Mars cost $15,000 ($89.95 plus $14,909.05 shipping, with roughly 14-18 month delivery time), we'd probably see similar tricks being hacked out of 10 year old videocards by Martian programmers today.

Re:8 bit audio?

[Lunix Nutcase]

No they didn't since the z80 doesn't.do the decoding. The dsp does.

Re:8 bit audio?

[Miamicanes]

I'm not 100% certain, but I'm pretty sure that single-bit SPI reads from microSD are too slow for realtime 16-bit PWM stereo. In other words, even if you buffered a few bytes in the chip's SRAM, the time it would take to physically shift 32 bits from the card (for the next two 16-bit samples) would exceed 1/44,100th of a second. In fact, if you were trying to bitbang 16-bit 44.1KHz stereo audio, I'm not sure you'd even have enough time to iterate through the 32 bits and decide whether or not the output should be high or low at a sufficiently high rate to avoid audible artifacts.

There are some things an 8-bit CPU just wasn't meant to do, and high-quality digital audio is one of them. It makes more sense to just wire a dedicated .mp3 codec chip up to the flash, and use the 8-bit CPU as the controller (in fact, that's basically what most dedicated MP3 players used to DO circa 2001). You use the MCU to do things like sense button presses, and communicate with the mp3 player chip itself (and possibly the amplifier chip) via i2c or SPI.

Nowadays, the moment of truth for jumping to ARM (instead of adding ASICs to 8-bit MCUs) tends to arrive with network connectivity. You can pair an 8-bit MCU with a Wiznet chip, but at that point the 8-bit MCU starts to feel kind of vestigial, and it usually ends up being cheaper to just step up to an ARM9 paired with a dumb ethernet chip instead of pairing a relatively expensive Wiznet chip (that does the heavy lifting for tcp/ip) with a mid-level 8-bit MCU.

Re:8 bit audio?

[mikael]

My favorite one was adding a battery and real-time clock onto the cartridge so that the game could have specific times of the day when certain actions would be possible. Add a microcontroller and the cartridge would continue to play the game even when out of the console.

Other Enhancement Chips

Re:8 bit audio?

[tibit]

Huh? Using hardware SPI ports, I'm very comfortably acquiring 16 bit data at 80ks/s using an 8 bit CPU that runs at about 8 MIPS. And that requires pushing 3 bytes both ways to and from the ADC, using a rather roundabout way of getting DMA to handle that. Even if it run on interrupts, it'd still be "reasonable": about 2.5MIPS would be lost for interrupt handling. The SPI in this application pushes an aggregate of 3.84Mbits/s (half of it each way).

It'd take a fairly crippled chip to require bit-banging anything. With any decent 8 bit CPU, SPI is handled in hardware, perhaps even with hardware FIFOs that are more than a byte deep.

I've used a souped-up 12 bit PIC (as 8 bits as it gets!) -- the Parallax SX48 to not only bit-bang to two 16 bit ADCs and DACs at 32 ks/s, but I was also doing an adaptive FIR filter. Everything ran without interrupts, in straight-line code. All I had for FIRs was shift-and-add. I used an external RAM chip for a buffer because internal RAM was a whoopee-de-doo 256 bytes :)

Re:8 bit audio?

[tibit]

I do agree about the "moment of truth" though. But I personally like faster architectures -- XMOS XC-1 running at 125 MIPS per thread with 4 threads running in parallel lets you do some spectacular things purely in software. Say running USB 2.0 at maximum speed, and running 100mbit ethernet.

Parallax Propeller I pushes 20 MIPS per cog (thread), with 8 threads running that gives 160 MIPS total, but it doesn't have a multiplier so I couldn't use it for my number crunching. It lets you emulate Z80 in a single thread, people are running CP/M on it, in a single chip.

Re:8 bit audio?

[jones_supa]

To me it seems the confusion here happened as you replied to MightyMartian (#37754420) while you probably intended to reply to Hatta (#37754338). Right?

Re:8 bit audio?

[bill_mcgonigle]

when 2600 was a videogame system and not a magazine dedicated to hacking

Flag down, ignoring a common cause.

It was remarkable that Atari was both a corporation and cool enough to name their flagship product after the Captain Crunch tone. Never happen today, which saddens me (OK, Facebook status updates are limited to 420 characters, but that's comparatively weak sauce).

(great comment, by the way).

Re:8 bit audio?

[hplus]

No. He meant to tell MightyMartian that the product he linked does not decode mp3s with 8-mit hardware.

Re:8 bit audio?

[bhtooefr]

#1: What cartridge WAS this? Not finding anything on it.
#2: I'd consider coprocessors in the cartridge a valid approach - look at Nintendo. In the NES era, they had "mappers" (which did a similar function to the Atari bank switching hardware in theory) that also had extra counters, added RAM, graphics upgrades, sound upgrades, IRQ generation, etc., etc. In the SNES era, they had DSPs, math coprocessors, second 65816s, and even full-blown RISC CPUs.

lolwut

[Lunix Nutcase]

The Microtouch is a mobile media device that aims to become an open-source alternative to the iPod Touch.

Yeah keep dreaming.

Re:lolwut

[Anonymous Coward]

If only he have done a cross breeding with his Minty MP3 player, it could be one step further to this goal.

Re:lolwut

[b0bby]

It's true, this looks like more of an alternative to an old Palm. Having said that, I like my old Palm & I'd like one of these too! I doubt I'll drop $70 plus whatever a battery costs on one, though.

Re:lolwut

[Coren22]

(her) Lady Ada didn't give it away to you?
http://en.wikipedia.org/wiki/Ladyada

Cute, Smart, Inventive...I know I'd love to date her :)

Re:lolwut

[tsa]

That's exactly what I thought. A device these days is as good as its software is, and just because of that it will never be an iPod Touch. If you want an open source media device just buy a Nokia N900 and don't complain about the lack of quality software for it.

Re:lolwut

[Anonymous Coward]

And hope you can get one in decent condition and it doesn't break somehow. I've moved on to my second N900 now the modem and GPS on my first has stopped working, its still under warranty so I can send it off for repair, but it is unlikely I'll get it back, they'll probably decide they can't fix it and replace it with an E7 or N8.

CC except this video, which infringes copyright

[Anonymous Coward]

Why did they use a commercially owned song for this video?

WHY

Gyro, Compass, etc

[Servaas]

But never an infrared light! Something like this would be perfect for a HTPC remote.

Re:Gyro, Compass, etc

[vlm]

But never an infrared light! Something like this would be perfect for a HTPC remote.

Or a robot remote control complete with video feed from the robot.

Re:Gyro, Compass, etc

[wierd_w]

Surely you could place an IR transmitter circuit on the programming interface header? An IR light is just a digital pulse code emitter.

Or did you want it to be a programmable universal remote, where you need a full blown IR tranciever so you can capture your OEM remote's pulse codes?

Open-source alternative to the iPod Touch ?

[perpenso]

open-source alternative to the iPod Touch

... 8-bit microcontroller with only 2.5K of RAM ...

As someone who has programmed microcontrollers and 8-bit CPUs back in the day I think this is a pretty cool device.

But iPod touch alternative? Seriously?

8-bit microcontroller vs 32-bit embedded processor with integrated FPU
2.5K RAM vs 512M RAM
28K FLASH vs 8G FLASH

Re:Open-source alternative to the iPod Touch ?

[rwade]

But iPod touch alternative? Seriously?

2.5K RAM vs 512M RAM

From wikipedia, Apple has included only 256MB of RAM in even the latest model of the iPod Touch.

Re:Open-source alternative to the iPod Touch ?

[vlm]

open-source alternative to the iPod Touch

... 8-bit microcontroller with only 2.5K of RAM ...

As someone who has programmed microcontrollers and 8-bit CPUs back in the day I think this is a pretty cool device.

But iPod touch alternative? Seriously?

8-bit microcontroller vs 32-bit embedded processor with integrated FPU

2.5K RAM vs 512M RAM

28K FLASH vs 8G FLASH

On the other hand, who would have guessed that in 2011, the "top game for the masses" would be a remake of the atari 2600 classic, Artillery Duel. I think this machine could easily out do that.

http://en.wikipedia.org/wiki/Artillery_Duel

Re:Open-source alternative to the iPod Touch ?

[Lunix Nutcase]

Even still this thing doesn't even remotely match the features of an iPod touch. It can't even play mp3s. Let alone the fact that the.iPod touch has a much higher res screen, can play 720p video, can do opengl es 2.0, etc. To claim this is even remotely an iPod touch alternative is laughable.

Re:Open-source alternative to the iPod Touch ?

[perpenso]

But iPod touch alternative? Seriously?

2.5K RAM vs 512M RAM

From wikipedia, Apple has included only 256MB of RAM in even the latest model of the iPod Touch.

Minutes ago wikipedia was showing 512 for the 4th gen, and the error was fixed between my post and yours. :-)
18:30, 18 October 2011 12.70.47.254 (talk) (38,640 bytes) (Models: changed ipod 4th gen from 512meg ram to 256meg. the iphone 4 has 512 not ipod 4th gen. This is also stated by the url that is attached to that sentence.)

Re:Open-source alternative to the iPod Touch ?

[TrancePhreak]

The iPod Touch only has 256MB of RAM in the 3rd & 4th gen, 128 in the others. iOS takes up a good chunk (roughly 80MB). I see someone has edited the wikipedia page on the iPT to directly contradict this. If you read iFixit's teardowns they confirm my information.

Re:Open-source alternative to the iPod Touch ?

[rwade]

Minutes ago wikipedia was showing 512 for the 4th gen, and the error was fixed between my post and yours. :-)
18:30, 18 October 2011 12.70.47.254 (talk) (38,640 bytes) (Models: changed ipod 4th gen from 512meg ram to 256meg. the iphone 4 has 512 not ipod 4th gen. This is also stated by the url that is attached to that sentence.)

No shit? That is extremely weird. The iPhone 4 has 512MB and was released near the release of the 4th generation iPod Touch -- I assumed that that was the root of the confusion.

Many believe the iPod Touch is simply a contract-less iPhone, which is hardly the case -- it is indeed a contract-less iPhone with significant sacrifices in its bill of materials -- among these compromises is a reduction in RAM. Few seem aware of that distinction -- somewhat odd that wikipedia reported 512MB recently; I myself reviewed the page not too long ago and I swear that it said 256MB...

Re:Open-source alternative to the iPod Touch ?

[perpenso]

The iPod Touch only has 256MB of RAM in the 3rd & 4th gen, 128 in the others. iOS takes up a good chunk (roughly 80MB). I see someone has edited the wikipedia page on the iPT to directly contradict this. If you read iFixit's teardowns they confirm my information.

256 is what I recalled but I went to wikipedia and double checked, apparently I caught the page immediately before it was corrected. :-)

Re:Open-source alternative to the iPod Touch ?

[devent]

If you go to their page they say you can use "Both MicroSD and MicroSD High Capacity cards are supported. ". So you have way more then just 28K flash. I don't really know why you need a "32-bit embedded processor with integrated FPU" for something like the iPod. From the video and from the pictures the microtouch seems very capable.

Re:Open-source alternative to the iPod Touch ?

[Yvan256]

I don't think the iPod touch has to access its internal flash storage via a slow SPI interface.

Re:Open-source alternative to the iPod Touch ?

[perpenso]

I don't really know why you need a "32-bit embedded processor with integrated FPU" for something like the iPod.

Just to be clear, iPod touch. Consider gaming, especially 3D gaming. If we were talking iPod nano then the comparison would be a bit more realistic.

Re:Open-source alternative to the iPod Touch ?

[Anonymous Coward]

OSLSE (Open Source Low Self-Esteem): A curious disorder. Symptoms include comparing a 8-bit handheld Pac Man game with less processing power than a modern toaster to an iPod Touch.

Re:Open-source alternative to the iPod Touch ?

[WalrusSlayer]

But iPod touch alternative? Seriously?

2.5K RAM vs 512M RAM

From wikipedia, Apple has included only 256MB of RAM in even the latest model of the iPod Touch.

Uh, ok, so it's only 1,000 times the RAM versus 2,000 times the RAM. This invalidates the GP how again? While the device is impressive, there is only so much you can squeeze out of such a resource-constrained environment. There is a reason the iPod Touch's RAM spec has an "M" after the numbers instead of a "K". Or perhaps you thought the engineers picked that number for the hell of it.

Need a TCP/IP network stack? SSL? A modern GUI? Codecs? Good luck doing that in 2.5K.

Even if you could wave a magic-pixie-dust-wand and somehow make all that happen and more, you are going to spend an inordinate amount of resources writing code that has to do it's job with only 1 byte of RAM, since the rest of the code took up the other 2.499K already. So while you can beat your chest and show how you managed to squeeze a bunch of functionality into a small footprint, that still comes at a cost.

Re:Open-source alternative to the iPod Touch ?

[WalrusSlayer]

...and at 10PM I shouldn't be doing math in my head. Make that roughly 200,000 times the RAM vs 100,000 times the RAM.

Re:Open-source alternative to the iPod Touch ?

[UnknowingFool]

Huh? If the iPod Touch didn't have access to it's internal storage, how could it do anything like play music?

Re:Open-source alternative to the iPod Touch ?

[Anonymous Coward]

Let me be the first to say: Whoosh

So far every smart phone released after the iPhone has been called the next iPhone killer by one party or another. So calling a touch device without GSM/3G capabilities the "ultimate iPod killer" defenitely is tongue in cheek.

Re:Open-source alternative to the iPod Touch ?

[Anonymous Coward]

Try reading that again

I don't think the iPod touch has to access its internal flash storage via a slow SPI interface.

Re:Open-source alternative to the iPod Touch ?

[drinkypoo]

What's really sad is that this is a dupe of a story that came here months ago, used essentially the same inflammatory headline, and made just as much sense. Not only does it not have audio, but it doesn't have enough horsepower to play an mp3 anyway. Further, all the IO pins are in use, so unless you dismount the accelerometer, you can't actually use it for anything useful, like control of another system.

This is a big (well, small) jackoff waste of time piece of shit, and I am dismayed to see it on the front page again. It's not that I could create this thing; it's that it has no fucking purpose except to waste your time and money.

Directions?

[datavirtue]

The post mentions directions, but I have downloaded the source, perused the blog, looked through the SF page and have found no instructions, parts lists or anything. If someone knows where they are please let us know. I found change log info, that is it.

Oh really?

[Anonymous Coward]

Considering most artists are compressing the shit into a 4 bit dynamic range during what they call "mastering" nowadays, 8 bits is plenty enough, truthfully.

Re:Oh really?

[jones_supa]

Is it really low as 4 bit, or were you exaggerating? My guess was that it is something like 10-12 bits.

Cool device!

[AnotherAnonymousUser]

The device looks like a badass precursor to a lot of things I'd love to design. The demo comes across like the 8-bit World of WarCraft trailer.
http://www.youtube.com/watch?v=KlwIwYqjNlc&feature=related
Scrolling...
COMICS...
Now with LUSH Hyperlink goodness...

Now with...

[caius112]

Apparently, it now comes with reversi!
What an incredible deal!

Touch screen requires calibration

[bigtrike]

The touch screen appears to require calibration, just like an old Palm.

Re:Touch screen requires calibration

[brim4brim]

You don't have to do it all the time though do you? I presume it is calibrate and stored. All touch screens require some sort of calibration initially I would have thought, I'm guessing Apple etc... just do it for you or with newer screens that it is set once or auto-calibrated.

How do these images fit in 2.5k RAM?

[Lord Lode]

I really wonder. 2.5K RAM would allow max around 2500 letters, or a single 256-color picture of 50x50 pixels.

Re:How do these images fit in 2.5k RAM?

[Anonymous Coward]

They are read directly from the MicroSD media card.

Re:How do these images fit in 2.5k RAM?

[perpenso]

I really wonder. 2.5K RAM would allow max around 2500 letters, or a single 256-color picture of 50x50 pixels.

With static text and images you can put them into the 28K FLASH. You only need RAM for things that change.

Re:How do these images fit in 2.5k RAM?

[Lord Lode]

Cool project! Nice that they have such smoothly scrolling images and text this way!

Re:How do these images fit in 2.5k RAM?

[Beorytis]

I'm gonna guess the images are in the microSD card and the 2.5k RAM is just for the program's working memory.

Re:How do these images fit in 2.5k RAM?

[Yvan256]

The LCD itself has internal RAM to display the image.

Re:How do these images fit in 2.5k RAM?

[Sleepy]

As perpenso said, these things don't use RAM for data.

These Atmel processors come with (besides the "CPU") RAM, flash RAM, and EPROM storage. External SD storage and more RAM, Flash etc are available if you add it yourself to the board.

So anyways, your script/sketch is saved to flash, which loads up in RAM (just like a regular script or program).
If you code things correctly, your bitmaps, your font definitions, are all in flash memory and so almost no RAM is used by that resource.

Some folks don't care, and the resource is embedded into the script (which means the resource lives in RAM). This is fine as long as you have enough memory and you weren't expecting other folks to run your sketch on smaller processors.

For end user data like an ebook on SD card, that gets loaded straight from the SD card and tossed onto the screen. The system is not trying to load the whole thing before display (which would blow out memory). Instead you scan and display things line by line... like you would do in an old-school shell script when your shell/console had very little memory (even on a server).

Re:How do these images fit in 2.5k RAM?

[Vario]

So this would be the answer how it is possible to display so much information with so little memory. That means that the CPU basically has 320x240*24 bit = 225K of video memory to draw the picture in.

Re:How do these images fit in 2.5k RAM?

[tibit]

The RAM in the CPU is acting pretty much as the cache would in a larger CPU. Bulk data is stored off-chip -- either in the display's own framebuffer, or on the SD card.

1-bit DAC defined

[tepples]

A "1-bit DAC" is a time-proportioning PWM DAC, as seen on a Game Boy Advance or Nintendo DS, or a delta-sigma DAC, as seen on plenty of portable CD players.

Re:1-bit DAC defined

[zAPPzAPP]

In that case, the information is in the timing of the edges. Anyway it is not "1 bit" of information.
That's like saying serial communication is 1 bit.

Re:1-bit DAC defined

[tepples]

You could think of it that way. A "1-bit DAC" in essence translates a PCM digital signal into numerous edges in such a way that a simple analog filter bank can reconstruct the signal.

Re:1-bit DAC defined

[Anonymous Coward]

In that case, the information is in the timing of the edges. Anyway it is not "1 bit" of information.
That's like saying serial communication is 1 bit.

Oh, so if we use your definition then the microcontroller in this device is a 128bit cpu if the software perform 128bit calculations.
The point people are trying to make is that Hatta is a retard for thinking that the statement "8-bit microcontroller" says anything with sound quality.
Pretty much any 8-bit controller out there is a 8/16-bit controller (Has been for the last 35 years.) and today you have to be familiar with the field to easily find one without a couple of 16bit timers with PWM capability.
Most MP3-players I have seen based around the CPU-family used in this project has an external chip for MP3 decoding. If you had bothered looking at the actual project you would have seen that they clearly state that they don't have such a chip and if I were to speculate one of the reasons could be that they don't have an audio plug or speaker mounted on the board. It is obviously NOT an MP3 player. If you want an MP3 player you either buy one or build one of the 1000 different MP3 player projects you can find on any forum dedicated to 8-bit microcontrollers. What you don't do is to go to this project and complain about it not having MP3 capability.

Re:1-bit DAC defined

[bill_mcgonigle]

Cool, thanks. I had a Sony Discman in high school that had a "1-bit DAC" marketing sticker on it. My college 'Physics of Music' prof told me it was PWM, but the article you posted finally clears it up for me. One more off the eternal 'figure this out' list!

Re:1-bit DAC defined

[TeknoHog]

Serial communication is 1-bit. It just takes a higher transfer rate compared to 8-bit parallel, for example. The essence of information transfer is how many total bits of information you have per second, not the size of the parallel bus you use to transfer them. In fact, no matter how many bits you use, the information is still in the timing of the edges, just like you said.

As for the 1-bit DAC, you can forget about PWM and delta-sigma for a while. They are refined implementations, but the basic ideas of Shannon and Nyquist work for a genuine, simple 1-bit DAC as well.

The problem with any digital audio system is quantization noise. Even if you fulfill the Nyquist criterion for frequencies, you have a limited number of signal levels. You can reduce this noise by oversampling. Basically, by 2x oversampling in a 1-bit DAC you can essentially create an average level halfway between 0 and 1. With higher oversampling, you can create more of these average levels. You can replace an 8-bit DAC by a 1-bit one, if the latter has 256x the sampling rate, and you should hear no difference. Actually, the latter should sound better, since it is easier to generate perfect 0 and 1 signal levels, compared to the 256 levels that may not be equally spaced.

Jethro Tull

[Anonymous Coward]

Thank you for the Jethro Tull soundtrack !

I always knew 16 bits was over the top

[TheChrisCarroll]

When I were a lad, we used to dream of having 2.5K of Ram. Would have been like having a hard disk to us.

Why not just make it Arduino compatible?

[tlhIngan]

Seriously, they want open hardware, they might as well go Arduino. Same class of processor, and wildly popular.

Heck, this thing's downfall might be that it's open and NOT Arduino compatible!

Re:Why not just make it Arduino compatible?

[Anonymous Coward]

How utterly annoying. It's open source and open hardware, you can go right ahead and "scratch that itch" to make it Arduino compatible. (I assume that means making an arduino shield?)

> Heck, this thing's downfall might be that it's open and NOT Arduino compatible!

You're sure it's not because it's a underpowered tinkerer's curiosity that nobody would actually use day-to-day? It can't even play mp3s.

ATmega32u

[Yvan256]

Why did they use the ATmega32u? IMHO a better choice would have been the ATmega328. Instant compatibility with Arduino libraries.
 

Re:ATmega32u

[QuasiSteve]

Probably for the built-in USB module? Compatibility with Arduino libraries is not all that important for this device and those who would want to hack away at it.

Re:ATmega32u

[Anonymous Coward]

More I/O pins, USB support (slave, not host), more RAM, more timers, more DACs, etc..

Oh, and it already has instant compatibility with most open-source Arduino libraries -- unless you're specifically accessing functional units not present in the 32U4, the same code will run on both; any differences in addresses will be taken care of by the appropriate header file.

Re:ATmega32u

[zwarte piet]

Because the 328 does not have enough pins. (28 or 32 pins versus 40/44 pins)

I don't get it either.

[Vario]

How is this possible with so little RAM? It has an image viewer app. A single 320x240 8 bit image is 75K and somehow the LCD needs that data for smooth scrolling at 25fps. So does the processor basically generates a few lines of pixels, sends those to the LCD and then continues rendering/reading from SD card the next few lines and manages all that at 25fps?

Re:I don't get it either.

[Anonymous Coward]

No the LCD controller (ILI9325 http://www.adafruit.com/datasheets/ILI9325.pdf) has the framebuffer for the LCD panel. The micro streams the data to it over SPI like a cellphone (think Nokia std phone not iPhone) or (if the micro is fast enough) using the RGB interface.

Perhaps he meant iPod nano ?

[perpenso]

Another post made me think of a very generous interpretation of the original quote. Perhaps the author meant to type "nano" rather than "touch". An iPod nano-like device would be a more realistic target.

256M, 512M, they're both essentially infinite in c

[fnj]

Oh, well that's different then. It's only 104,858 times as much RAM, not 209,517 times. Sure does make it a serious contender now.

Graphics in text mode

[tepples]

A pure text mode display could not show graphics.

The Nintendo Entertainment System has a pure text mode display, albeit with sprites on top. Games show graphics by redefining the font to include pieces of graphics. In fact, some games (such as Color a Dinosaur, Elite, Hatris, Qix, and Videomation) operate by rewriting the font in real time, treating the font sheet as if it were a bitmap with its pixels in a funny order. But I'll grant that the graphics on this device don't look anything like text mode, so the VRAM must not be part of the 2.5 KiB, just as the NES VRAM isn't part of its 2 KiB.

Why the hell did they go with an 8-bit uC?

[Anonymous Coward]

It's not even like 32-bit microcontrollers are hard to find or expensive or even difficult to prototype with. They're several times faster in numerous ways.

8-bit or bust

[FyberOptic]

It's always interesting to see what people can do with an AVR, but this thing reminds me way too much of the little wallet-sized photo viewer I received recently. The screen on it was dreadful, and the resistive touchscreen was as bad or worse than I always remembered them as being. But, it served its purpose overall I guess, and I'm sure it was dirt cheap to assemble in some Chinese factory.

There's always a place for such a product, such as to developing countries, or schools as an incentive to read, etc. The problem is that the only places where it would actually be useful is not likely to be where it would end up. When there's actually somebody putting money behind them, those kinds of products usually end up as the free gifts you get for asking about signing up for some insurance company or something.

Anyway, it's neat, and I've developed with AVRs myself, but I must admit I'm still partial to the Z80. I always love finding out a particular product is still using an embedded version of one of those.

Re:8-bit or bust

[rasmusbr]

That's true, but on the other hand many of these products only sell to enthusiasts and therefore work as a sort of tutorial for people who want to learn how to design and build stuff. A person can study the design files for this thing and learn something about circuit design and PCB design.

Perhaps we'll eventually see big teams that develop complex FOSS hardware projects for consumer or commercial applications. Maybe one day a team of developers will beat the iPhone the same way that Firefox beat Microsoft Explorer. There is absolutely nothing stopping that from happening except the general lack of understanding about how to get a sufficiently big and stable cash stream going for a FOSS project, and the general difficulties of setting up small-scale profitable production of physical devices.

Okay, so there's quite a bit stopping that from happening, but I wouldn't be surprised if some people find ways to do it.

Eagle is proprietary

[Anonymous Coward]

This is the Java trap.

Apps stored in firmware?

[sgt scrub]

Microtouch as an application framework of sorts that allows multiple applications to be built into the firmware.

It sounds really cool; but, how many flashes can the firmware take?

Why?

[ckaminski]

When 32bit ARM SoC's like the Guruplug are getting cheaper?