MK2 Serial Communications Speed on USB

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Don't Panic. Please wash hands.
  • I've got my MK2 working and added it into my dev chain, using the mk2codenet to dump build directly to the memory of the MK2


    Is there a way to bump up the baud rate?

    I've been spoiled running direct to emulation, but is there a way to bump up 19.2 to 38.4 or higher?

  • 19k2 was chosen in order to have the smallest-possible deviation with the 27MHz crystal that the hardware uses (which in turn was chosen to have zero deviation for the 50/60Hz TOD clock). Further, we have to mind that the serial link between the MCU and the USB-Serial converter is without handshake, so incoming data could possibly overrun the MCU. So while technically possible to set let's say 38400 Baud with acceptable tolerance, the MCU would probably not be fast enough to pick up data in time before it has relayed it into the rest of the hardware.


    27MHz on a 1T8051 is a lot, especially in comparison to a 985kHz 6502 system. However, it won't do wonders, especially not when it has other real-time tasks to fulfill, such as monitoring the Restore key to generate NMIs :-)


    I see two incentives for you:


    1) (the smart method): Reduce your memory dump to "diff only": If you keep track of what's been transferred already, you can save a great deal of time between compile/assemble steps. Transferring only the delta could be compared to a smarter make file, as opposed to "make clean".


    2) (the easy method): Go for an RR-Net MK3. Remember that Codenet was originally developed for a networking card that has 4k buffer for incoming and outgoing packets, and handshaking is handled by the networking chip.


    Xmas isn't too far away, and UPS makes really fast international deliveries :-)