Coder's cable: Difference between revisions

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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).
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).


- Using the Dreamcast's clock:
'''Not all common baudrates work''', so the recommendations are:
* These baud rates should work with most systems/cables: 38400, 57600, 115200, 230400. (eg: lik-sang cable)
* '''up until 115200''', you can use the common baudrates: 9600, 19200, 38400, 57600, 115200
** Note that 230400 does not work yet with the current dc-load-serial (1.0.6), but a fix is incoming
** if 115200 does not work, you can add the "-e" speedhack option
* These baud rates need a good cable: 500000, 781250, 1500000. (eg: [https://www.retroonyx.com/product-page/dreamcast-usb-coders-cable retroonyx cable], but even  with those it's probably not a 100% guarantee)
* '''higher baudrates''':
* Specifying non-standard baud rates like 781250 might be tricky/impossible for most programs. Picocom for example accepts that value:
** try first with the '''dreamcast-specific baudrates''' (223214, 260416, 312500, 390625, '''520833, 781250, 1562500''')
** picocom -b 781250 -d 8 -y n -p 1 /dev/ttyUSB0 
** '''230400''': use the -e speedhack option
** '''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%))
 
Recommended USB-Serial chips:
* FDTI's '''FT232R'''-like chips:
** '''good until 781250''', does not support 1562500.
** 500000 and 1500000 will not work with all chips/on all pc.
* Silicon Labs '''CP2102N''':
** under review, should support 1562500.
 
How to build/buy a cable:
* Buy: eg [https://www.retroonyx.com/product-page/dreamcast-usb-coders-cable retroonyx cable], FTDI-based cable.
* Build:
** DC serial connector: cfr DC SD Adapter V2
** select a usb-to-serial chip/cable, cfr recommended chips above
** connect TXD <-> RXD, RXD <-> TXD, RTS <-> CTS, CTS <-> RTS


- Using an external clock (SCK pin):
(TODO)


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Revision as of 09:27, 3 July 2023

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).

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)
    • 230400: use the -e speedhack option
    • 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%))

Recommended USB-Serial chips:

  • FDTI's FT232R-like chips:
    • good until 781250, does not support 1562500.
    • 500000 and 1500000 will not work with all chips/on all pc.
  • Silicon Labs CP2102N:
    • under review, should support 1562500.

How to build/buy a cable:

  • Buy: eg retroonyx cable, FTDI-based cable.
  • Build:
    • DC serial connector: cfr DC SD Adapter V2
    • select a usb-to-serial chip/cable, cfr recommended chips above
    • connect TXD <-> RXD, RXD <-> TXD, RTS <-> CTS, CTS <-> RTS


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