Rockbox Development > New Ports
Rockbox Player - Project to design and build a Free/Open hardware audio player
scharkalvin:
--- Quote ---So, what's need more? We have microcontroler, SRAM, FLASH, USB, LCD, buttons. What about DAC?
--- End quote ---
Here's what's on the AVR32 cpu:
AVR32 based 32-bit MCU/DSP
Vectored multiplier co-processor, 32 KB on-chip SRAM, 16 KB instruction and 16 KB data caches, MMU, DMA controller. Peripherals include a 16-bit stereo audio DAC,2048x2048 pixel TFT/STN LCD controllers, 480 Mbps USB 2.0 with on chip transceivers (PHY) and, two 10/100 Ethernet MACs. Serial interfaces include RS232, USART, I2S, AC97, TWI/I2C, SPI, PS/2 and several synchronous serial modules (SSC) supporting most serial communication protocols.
So we have the DAC (only need a breakout connection and audio amp)
casainho:
--- Quote from: scharkalvin on December 10, 2007, 08:01:22 AM ---
--- Quote ---So, what's need more? We have microcontroler, SRAM, FLASH, USB, LCD, buttons. What about DAC?
--- End quote ---
Here's what's on the AVR32 cpu:
AVR32 based 32-bit MCU/DSP
Vectored multiplier co-processor, 32 KB on-chip SRAM, 16 KB instruction and 16 KB data caches, MMU, DMA controller. Peripherals include a 16-bit stereo audio DAC,2048x2048 pixel TFT/STN LCD controllers, 480 Mbps USB 2.0 with on chip transceivers (PHY) and, two 10/100 Ethernet MACs. Serial interfaces include RS232, USART, I2S, AC97, TWI/I2C, SPI, PS/2 and several synchronous serial modules (SSC) supporting most serial communication protocols.
So we have the DAC (only need a breakout connection and audio amp)
--- End quote ---
Good! :-) So in dev board we just need to solder wires for LCD, for headphones driver/amplifier and for buttons. $80 for dev board + $20 for nokia graphic LCD + $10 for the rest. It will not look good as an Ipod or a Sansa however It will be +-technically equal and total Free/Open hardware :)
I will put this information on Twiki page of RB. After I just need to find developers that can joint the project and buy their on dev boards e dev tools.
scharkalvin, do you want to participate? - I mean at buy also your tools.
scharkalvin:
--- Quote ---scharkalvin, do you want to participate? - I mean at buy also your tools.
--- End quote ---
Sounds interesting. I'll probably lurk around on the forum and irc and jump in with both feet a bit latter. I'll have some more 'mad money' available early next year.
BTW the Nokia LCD is a bitch to connect to as the connector is small and fragile.
You will need this as well http://www.sparkfun.com/commerce/product_info.php?products_id=600
which about doubles the cost.
Spark fun has a slightly cheaper LCD: http://www.sparkfun.com/commerce/product_info.php?products_id=8498
that uses a parallel interface (complete data available for the control chip on the website) that is a bit larger and only needs a few more wires to connect.
I can't tell from the photo or data sheet how hard this one would be to solder wires to or if a connector is available.
more info:
I looked at the schematic for the development board. The D/A converter is a Delta-Sigma type and the output is raw data, not true analog. So some external circuity is going to be needed to capture the audio. Probably a latch, and some op-amps as an active low pass filter and pre-amp. More research is needed to figure this out, (google). There is also an AC97 interface, not sure what that is about (probably an i2c interface to external mixer / level control hw). We'd need part of that for sw control of volume (would lose s/n ratio by adjusting volume by scaling d/a data).
Add schematic for d/a codeic interface from avr freaks.
casainho:
--- Quote from: scharkalvin on December 10, 2007, 09:20:37 AM ---Sounds interesting. I'll probably lurk around on the forum and irc and jump in with both feet a bit latter. I'll have some more 'mad money' available early next year.
--- End quote ---
Nice :) Could you add yourself to the list "People that are interested and can help"
http://www.rockbox.org/twiki/bin/view/Main/RockBoxPlayer
In the next weeks or so, we can work in advance before buy hardware, since we can read datasheets and have all information :)
About LCD, this: http://www.sparkfun.com/commerce/product_info.php?products_id=8498 , have 0,5mm pitch :( It's very difficult to solder, It's the same pitch as Nokia LCD and they wrote at Sparkfun:
Description: This is the itty-bitty connector for the Nokia color LCD. 10-Pins. Surface mount. Hard to find. 0.5mm pitch so be careful.
Can it be soldered by hand? Yes! Owen managed to solder wire wrap wire to the individual legs for testing - but then again, he's a magician. We can solder it well with a good PCB layout and easily with a stencil and hotplate.
http://www.sparkfun.com/commerce/product_info.php?products_id=570
So, no Nokia LCD and not this one, IMO.
About DAC, please don't laugh, but, what about 16 bit PWM + power drive? - yes, should be very low quality.
There are others projects Free/Open Source players that used DAC IC's, I will look at them. Did you look at that links in Twiki page?
casainho:
About DAC:
The CODEC chip is a TLV320AIC23 from Texas Instruments. You could also use TLV320AIC23B since it's an exact equivalent. It is a 24-bit resolution Sigma-Dealta CODEC supporting up to 96 KHz sampling rate and comes with a built in headphone amplifier. The CODEC (coder-decoder) converts the digital samples produced by the DSP into an analog signal that can be fed to the headphones. It can also convert the analog signal connected to the line-in jack into digital signals and feed it to the DSP for processing.
The CODEC chip has a control port and a data port. The control port is linked to the DSP's SPI port whereas the data port is linked to the DSP's McBSP port. The DSP can control the CODEC configuration (e.g. volume, sampling rate, mute, etc). The data port is used to transfer digital audio samples to/from the CODEC.
We need the TSSOP-28 package for the DSPdap board. You can obtain it through TI sampling or Digikey.
I took that information from DSPdap: http://dspdap.sourceforge.net/hardware.html
Also I asked the responsible for that player, to join the idea of make a Free/Open hardware player for RB. Here the thread:
http://sourceforge.net/forum/forum.php?thread_id=1834813&forum_id=697896
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