CXD2678 and CXD2680 - MiniDisc-wiki/md-firmware GitHub Wiki

The CXD2678 and CXD2680 SoCs are the last generations of Non-HiMD NetMD capable SoCs for portable MD recorders. They are the successor to the Type-R CXD2677. The CXD2678 was only used in the MZ-N10 and was replaced by the CXD2680.

The main difference (that we know of) between both SoCs is that the CXD2678 has 8MiB of DRAM and the CXD2680 only 2MiB.


CPU core ARMv4t, probably ARM7TDMI* based on Sony's SR11 cores
Flash size 640KiB
SRAM size 36KiB
DRAM size 2MiB (CXD2680), 8MiB (CXD2678)
NetMD Yes
Codec version Type-S

* The CPU does not have the typical co-processor interface for processor identification with MIDR, ruling out other cores

Memory Map

Start End Description
0x00000000 0x0009FFFF Flash
0x02000000 0x02008FFF SRAM
0x03000000 0x0300FFFF Peripherals A
0x0301FF00 0x0301FFFF Peripherals ?
0x03800000 0x0380FFFF Peripherals B
0x03F00000 0x04000000 Unknown, device freezes on access

Block Diagram

Based on random resources, educated guesses, and firmware (and probably not fully correct):

Peripheral Map

0x03000000 - 0x0300FFFF

Start End Description Notes
03000000 030000FF General/interrupts
03000200 030002FF General/interrupts IRQ/FIQ status registers here, containing reason for interrupt
03001000 030013FF GPIO
03002000 030020FF GPIO w A/D converter
03003000 030030FF SPI0 control
03003100 030031FF SPI0 buffer
03003200 030032FF SPI1 control
03003300 030033FF SPI1 buffer
03003400 030034FF SPI2 control
03003500 030035FF SPI2 buffer SPI2 is used for communication with integrated MD/DSP controller. XLAT (see 0x0300b000), is used for flushing the buffer and executing DSP commands. It seem that the buffer can also be flushed with other signals, maybe for other stuff? For example, during init a lot of data is sent, but it's not flushed with XLAT, but with another signal.
03003600 030036FF SPI3 control
03003700 030037FF SPI3 buffer
03003800 030038FF SPI control Probably used for setting the general SPI config, such as clock
03004000 030040FF SSB0 Link to RF AMP
03004100 030041FF SSB1/TSB1 REMOTE interface (part A)?
03004200 030042FF SSB2/TSB2 REMOTE interface (part B, maybe for sync recoding stuff)?
03005000 030050FF TIMER A Used for IRQ?
03005100 030051FF TIMER B Used for FIQ?
03005200 030052FF TIMER C Used for processing SPI/REMOTE/..., e.g. regular updates
03005300 030053FF TIMER D Used for other general system stuff
03005400 030054FF TIMER E
03005500 030055FF TIMER F
03005600 030056FF TIMER G
03005700 030057FF TIMER H
03005800 030058FF TIMER I
03007000 030074FF GPIO PWM control Maybe with D/A converter?
03007800 030078FF ? Unknown, not used
03008000 030080FF ? Unknown, not used
03009000 030090FF ? Unknown, not used
0300A300 0300A3FF ? Unknown, possibly related to ATRAC DSP signalling
0300B000 0300B0FF ATRAC DSP irq signalling linked to mon/xlat
0300B100 0300B1FF DRAM transfer address registers possible general registers that can be used for other things as well?
0300B200 0300B3FF ? Unknown, not used

0x0301FF00 - 0x0301FFFF

Start End Description Notes
0301FF00 0301FFFF ? Unknown, not used

0x03800000 - 0x0380FFFF

Start End Description Notes
03801000 03801013 ? Unknown, configured only a couple of times, to fixed values
03802000 038020FF Patch controller Used to apply virtual patches to the flash memory
03803000 038030FF DMA controller
03804000 038040FF ? Unknown, related to DMA transfer
03805000 038050FF ? Unknown, unused
03806000 03806FFF ? Unknown, unused, dump shows that a block of 0x100 bytes is repeated 16 times
03807000 038070FF FCU Flow control unit, controls transfers between buffers and md unit/dram
03808000 03808FFF Data transfer buffer A Used for putting padding on LP2 data
03809000 03809FFF Data transfer buffer B Used for putting padding on LP2 data
0380A000 0380A0FF FCU / PCM buffer control
0380B000 0380B0FF PCM buffer input
0380B100 0380B1FF PCM buffer First 32 words is PCM encoding buffer, inputted via 0x0380B000
0380C000 0380C02F USB controller General + control transfers
0380C100 0380C1FF USB Bulk MD -> PC Not used (only by homebrew)
0380C200 0380C2FF USB Bulk PC -> MD
0380C300 0380C3FF USB Interrupt transfers? Not used
0380D000 0380D0FF DES encryption DMA transfers can use DES unit to immediately encrypt transfers
0380E000 0380E0FF Monitor interrupts? Something with FOK