Cowon D2 Info

Introduction

The Cowon D2 is a flash-based DAP/PMP with a 320x240 touchscreen, SD card slot, FM radio and TV-Out. It comes in 2/4/8/16GB sizes, and there is also a version with DAB digital radio. An updated model known as the D2+ exists, which features an updated case design and a new firmware version featuring BBE+ audio processing.

Hardware

• CPU - Telechips TCC7801 - see TelechipsInfo
• LCD module - Samsung LTV250QV-F0B - contains the S6F2002 LCD controller IC
• Audio codec - Wolfson WM8985
• RAM: Samsung K4M56323PG 32MB
• NAND flash: Samsung K9LAG08U0M-PCB0 (2GB)
• PMU: Philips PCF50606
• FM: Sanyo LV24020LP
• Charger: Maxim 1874E
• DAB: Telechips TCC3110

Disassembly and pictures at AnythingButIpod.

Port Status

Rockbox is able to play music and run most plugins on the D2, however many functions do not work as intended because the internal flash filesystem driver is unreliable and read-only. There is a basic touchscreen driver which divides the screen into 9 areas, used to emulate a set of buttons. Most plugins are fairly usable, albeit with fairly basic button mappings.

The port runs on all current D2 and D2+ variants: 2 / 4 / 8 / 16GB internal flash, with or without DAB or DMB.

NOTE: The current Rockbox build is not fully functional - it is not in any way a replacement for the Cowon firmware. The following installation instructions are intended for a developer/test audience only.

Rockbox installation is similar to the iRiver H1x0 / H3x0: the bootloader build produces a bootloader.bin file, which needs to be patched into an original Cowon firmware using mktccboot. The resulting patched firmware is then flashed to the D2 using the normal firmware upgrade process. This mechanism is used to provide dual-boot functionality between the OF and Rockbox (to boot Rockbox, immediately set the hold switch after power-on).

Steps to Install

You will need a copy of your current Cowon firmware, ie. the D2(N).bin file from the '1' folder in an official firmware update archive. Note that this file is named D2.bin for DAB/DMB players, otherwise D2N.bin.

1. Compile a (B)ootloader build (in a new folder eg. rockbox/d2_boot).

2. Patch the bootloader into the Cowon firmware using the following command:

../tools/mktccboot path_to_firmware/1/D2N.bin bootloader.bin d2_patched.bin

3. Compile a (N)ormal build (use 'make' and then 'make zip', in a new folder eg. rockbox/d2_main).

4. Unzip the resulting rockbox.zip to the root of your player. (note: a pre-built "bleeding edge" zip can be found here).

The d2_patched.bin can then either be uploaded to the player using tcctool (don't forget to set the hold switch, as this is a dual-boot image), or flashed to the player using the usual firmware upgrade method. To do this rename the file to D2.bin or D2N.bin as appropriate, copy it to the root of the player, then boot the OF.

It is also possible to 'preview' a (N)ormal Rockbox binary on the device, by using tcctool to upload the rockbox.bin file (NOT rockbox.d2). Note that this is only suitable for minor development/testing purposes, since plugins/codecs are not updated when using this method.

Known Problems

• The internal flash (ATA/NAND) driver is not complete, and is not reliable. If the bootloader displays a "File Not Found" or "Bad Checksum" error, copy the rockbox.d2 file a second (or third) time and try again until it works. Similar errors may also occur when attempting to load themes, fonts, plugins, etc (eg. garbled text or "Incompatible model" errors).

• The internal flash is read-only at present, so unexpected behaviour can occur if Rockbox or a plugin tries to write to the disk. Due to this an "Error Accessing Playlist Control" will occur when starting playback due to this, and settings can't be saved (but defaults can be set up on a PC by editing .cfg files).

• Recent changes appear to have disabled the CPU cache in the bootloader, so the initial FAT mount takes longer than expected.

• Battery readings are not calibrated, and change significantly when a USB cable or AC adapter is connected. The estimated runtime should be ignored for the time being.

• The touchscreen driver sometimes registers incorrect presses. For this reason, menu navigation is easiest using the the physical PLUS/MINUS, MENU and POWER keys.

• The software USB stack is unreliable when enabled (frequently losing connection, freezing, and/or displaying panic errors). Unplugging the USB cable consistently freezes the player.

Work To Be Done

Things that need to be done before the port can be considered usable:

• Further investigation and implementation of the TelechipsNAND driver, at least to a usable read-only state. May share some common ground with TCC77x devices such as the LogikDaxPort and SansaM200Port (hardware rev. 1/2 only, not HARP or AMS based players).

• Implement a read/write SD(HC) driver - ThomJohansen is looking into this.

• Investigate and fix keymaps for various screens/plugins:
  • 5-band EQ (unusable due to apparent conflicts)
  • QuickScreen (left action does not work)
  • ...

• Investigate/calibrate battery readings and establish whether we need to do anything to enable full charging.

• Write the manual, and provide installation support in RockboxUtility.

Things that would be nice to have:

• Investigate use of the co-processor.

• Investigate use of DMA transfers (eg. could a mem-mem transfer be used to speed up copying the Rockbox framebuffer to the hardware framebuffer?)

• Recording (built-in mic, FM, line in via adapter cable)

• Investigate what can be done with the line out and TV out.

...and probably many more things I haven't even thought of yet.

Forum Thread

The New Ports forum thread for the D2 is at:

http://forums.rockbox.org/index.php?topic=10164.0

Firmware Upgrade

Firmware upgrades are in the standard Telechips "dual-crc" format (more info at TelechipsInfo). Firmware upgrade files (D2.bin or D2N.bin) are a raw, unencrypted dump of SDRAM (base address 0x20000000). This is loaded from flash during normal startup by an 8KB Boot ROM.

The device also has a USB boot mode, and can be accessed via the tcctool utility (in Rockbox SVN). USB boot mode is enabled by powering the unit off, then holding any of the keypad buttons ('-', 'M', or '+') while inserting the USB cable.

Note that the "dual-crc" format does not appear to be required when using USB boot mode.

Firmware Versions

There are several variants of the D2 retail firmware tailored for different markets and hardware versions. The variant is identified by the Major version number.

Firmware archives downloaded from Cowon are split into three subfolders, each containing one or more .bin files.

• "0" - Applying this D2.bin will perform a low-level format of the D2's internal flash. Use with care (and do not upload it with Tcctool!).
• "1" - D2.bin contains the main firmware image. You can "preview" different firmwares by uploading this file with Tcctool. This is the file that is patched by mktccboot.
• "2" - D2_rs.bin is some form of resource (graphics) archive. D2_font.bin contains the UI font. Both of these can be patched to provide different "themes", using utilities available at the iAudiophile.net forums.

D2+ firmwares follow the same version numbering and file naming scheme, except that file names begin with D2_P. It appears that the only reason a D2+ firmware cannot be flashed to a standard D2 is that the new firmware exceeds the 4Mb size limitation present in the standard D2 firmware flash routine (tcctool can be used to get around this limitation).

Technical Information

The TCC7801 has significant similarities to earlier Telechips SoCs such as the 76x (for which a datasheet was posted to the rockbox-dev mailing list here). The following hardware registers appear to be the same as the 76x:

(*the SDRAM controller appears to have a duplicate range at 0xF1001000, presumably for a second SDRAM bank?)

The IRQ/FIQ controller (base 0xF3001000) seems to be largely the same as the 76x (base 0x80000100) except there appears to be a priority mechanism whereby the IRQ number of the highest-priority IRQ occurring can be read from address 0xF3001080. 0xF3001044 bits 0,1 appear to be a master IRQ/FIQ enable flag.

IRQ numbers do not appear to be the same as 76x, although Cowon helpfully left quite a lot of debug text in their firmware (eg. search for '_HISR') which should help identify some of these.

GPIO ports

GPIO ports can be accessed as follows:

0xF005A0x0 = current value of GPIOx
0xF005A0x4 = direction for each pin (set = output, clear = input)
0xF005A0x8 = bits to set
0xF005A0xC = bits to clear

For example, the hold switch state is available by reading bit 3 of 0xF005A020. To enable the LCD backlight, write bit 6 to 0xF005A028.

GPIOA (base = 0xF005A020)

GPIOB (base = 0xF005A040)

GPIOC (base = 0xF005A060)

GPIOD (base = 0xF005A080)

GPIOE (base = 0xF005A0A0)

Notes:

• When USB is connected, C26 goes low.
• When AC Adapter is connected and powered, C26 goes low and D23 goes high.

ADCs

• ADC0 provides an indication of the keypad state for the '-', 'M' and '+' buttons.
• ADC1 appears to provide an indication of current battery voltage (note that the actual voltage can be read from the PCF50606 chip).
• ADCs 2-3 are unknown (both appear to fluctuate with a wide range of values).

LCD

The LCD is powered on and off using the sequences given in the LTV250QV datasheet. The LCD is not visible at all unless the backlight is enabled, so it is necessary to first set the backlight intensity using PCF50606 register 0x35 and then enable it using GPIOA6.

Hardware registers for the LCD controller are TBC (base = 0xF0000000), however a working initialisation sequence has been identified from the OF.

NAND flash

The following D2's have been observed:

• 2GB : 1x SAMSUNG K9LAG08U0M (8192 blocks, 128 pages per block, 2048+64 bytes page size)
• 4GB : 2x SAMSUNG K9LAG08U0M ""
• 8GB : 2x SAMSUNG K9LBG08U0M (8192 blocks, 128 pages per block, 4096+128 bytes page size)
• 16GB : 4x SAMSUNG K9LBG08U0M ""

See TelechipsNAND for further information.

Audio

Hardware equalizer bands EQ1 and EQ5 are used to provide bass and treble controls. At present a full 5-band equalizer is only available using software EQ (this is currently unusable due to keymap problems).

The WM8985 is powered by the PCF50606 regulator D3REG. In the original firmware this is configured for 3.3v output by sending 0xF8 to D3REGC1 (0x26).

Power management