From: Boris Gjenero <boris.gjenero_at_gmail.com>
Date: Sat, 20 Apr 2013 14:50:13 -0400

Over the last few weeks I've been working on a port to the RCA RC3000A
digital boombox. I now have flawless playback, including via the
speakers. The first successfully played song was Mika - Un Soleil Mal
Luné in FLAC format, from an SD card.

It's based on the TCC760 SoC, which has a USB boot mode allowing
convenient development without risk of bricking or need to write code to
storage. The mode is a bit different from later Telechips SoC supported
by tcctool: the 4th parameter is execution starting address not SDCFG. I
can still upload to SDRAM by first uploading a small program to set
SDCFG and then uploading to SDRAM.

Rockbox has drivers for the LCD, tuner and RTC. The LCD only needs a
different initialization sequence. The SoC has similarities to TCC77x
and the codec has similarities to CS42L55, but there are important
differences, so I'm making new drivers for them. I used Archos Ondio
ata_mmc.c as a starting point for the SD driver because it also uses
SPI, but it seems I should be using higher level SD code from another
later driver for SD cards. It's too bad that SD drivers don't separate
low level communication with the card from higher level code that sends
commands, like with ATA. I intend to keep the two separate in the SD
driver, perhaps with an eventual goal of splitting other drivers that
way. I'm not planning to use the OHCI USB host controller for storage
access, but the Telechips USB device controller seems easy and I should
be able to use that for Rockbox USB.

Here's a summary of what the RCA RC3000A contains
CPU: Telechips TCC760 SoC with ARM940T core, which the OF runs at 96 MHz
Memory: 2 MB SDRAM, 2 MB NOR flash with over 1 MB free
LCD: SSD1815, 128x64, 1bpp, white backlight
Storage: 512 MB internal NAND flash, SD card slot with SPI mode access
using GSIO, OHCI USB host port.
Tuner: TEA5767 radio module with 32767 Hz crystal
CODEC: CS42L51 with radio connected to AIN1 and line in to AIN2, the
output driving headphones, and a separate class D amplifier chip driving
the speakers.
RTC: PCF8563

Best regards,

Boris
Received on 2013-04-20