Coder's cable

The coder's cable is the name given to the serial-based cable some developers use to test and debug code during development. Originally, cables were connected to host devices via serial, but modern cable designs incorporate a USB controller instead. Coder's cables can also be used for other purpose's besides development, such as transferring VMU data back to a PC or dumping GD-ROMs (although quite slowly).

How to build/buy a cable

• Buy:
  • eg retroonyx cable, FTDI-based cable.
  • (only mentioned for historical purposes - not sold anymore since long - "Lik-Sang coder's cable" - max speed of 781250)
• Build:
  • DC serial connector:
    • best connector today is the one used by the DC SD Adapter V2 (+- 16 USD)

DC SD Adapter V2

• • select a usb-to-serial chip/cable (+- 10 USD)
    • Silicon Labs CP2102N:
      • Supports 1600000, which is a 2,4% baudrate mismatch with the Dreamcast, which seems acceptable for high speeds. Best chip that can be recommended today. Tests give speeds of 170-190 kByte/sec and more thanks to compression.
      • eg Adafruit CP2102N Friend (USB-C)
      • eg Silicon Labs CP2102N-MINIEK (mini USB)
      • eg DSD TECH SH-U09BL USB to TTL Serial Cable with CP2102N Chip
      • eg Colton's custom PCB - Kicad files to order a custom PCB with a CP2102N, to be soldered to the serial connector of a DC SD Adapter V2

• • • FDTI's FT232R-like chips:
      • good until 781250, does not support 1562500.
      • 500000 and 1500000 will not work with all chips/on all pc, because of a 4% baud rate mismatch with the baudrates of the Dreamcast.
        • Even if you're lucky, you won't really get 1500000-worthy speeds - more probably around 130-150 kByte/sec...

• • connect the following pins (cfr Serial_interface):
    • GND <-> GND
    • TXD <-> RXD
    • RXD <-> TXD
    • RTS <-> CTS
    • CTS <-> RTS

Software to use

Dcload-serial

Supported Baud Rates

Not all common baudrates work, so the recommendations are:

• up until 115200, you can use the common baudrates: 9600, 19200, 38400, 57600, 115200
  • if 115200 does not work, you can add the "-e" speedhack option
• higher baudrates:
  • try first with the dreamcast-specific baudrates (223214, 260416, 312500, 390625, 520833, 781250, 1562500)
    • Disclaimer for Linux only: needs dc-tool-ser (host) changes from 4 september 2023 to select custom baudrates
    • Disclaimer for MacOS only: custom baudrates are not supported yet
  • 230400: use the -e speedhack option if you absolutely need 230400 at pc-side, but the DC will use 223214 or 260416 anyways.
  • 500000 and 1500000: you can try, but that will not work on all pc (the mismatch with the baudrate of the Dreamcast is sometimes too big (4%))

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