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Author Topic: A2000 serial speed  (Read 725 times)


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Offline RetroNinjaTopic starter

A2000 serial speed
« on: September 20, 2023, 05:43:28 PM »

I'd like to use my A2000 to connect to a PCengines router. The router talks through the serial port at a fixed speed of 115200. I've read other places that this speed is too fast for the A2000. Does anyone know if the limitation is from CPU+custom chip? just CPU? Can I install an old Zorro II GVP I/O card (parallel + serial) to get a higher speed? With the serial processing handed off to the I/O card would I be able to achieve the needed speed?

Offline Castellen

Re: A2000 serial speed
« Reply #1 on: September 20, 2023, 09:14:23 PM »
While the A2000 serial port will operate at 115200 baud, the limitation is that the 68000 CPU is not able to service receive data interrupts fast enough, meaning you'll get a lot of RX data over-runs, even if you use hardware flow control.  i.e. a loss of serial data.

If you have a CPU expansion, such as a 68040, you shouldn't have many issues with transferring large blocks of data at 115200 baud with the onboard serial port.

You can do more with third party serial port expansions since most of them include a FIFO buffer in hardware.  This results in far less interrupts needed by the CPU to fetch the received data, since the interrupts collect received blocks of data from the FIFO buffer as opposed to individual bytes.