Multiple writes to AtariVox requires wait for acknowledgement

[+Bruce-Robert Pocock]

  Posting this for posterity:

 

When writing to the AtariVox EEPROM (and I presume MemCard/SaveKey), it seems that it's necessary to wait for the write-commit to be acknowledged before starting a second write, or the second write will be silently ignored. Tested both on Stella's software AtariVox emulation and using a Harmony cart with a real AtariVox.

 

Basically all you have to do is something like this:

WaitForI2CAck:
          jsr i2cStartWrite
          bcs WaitForI2CAck
          jsr i2cStopWrite

Having the second write be completely ignored was driving me nuts trying to debug, and just adding a few frames of wait time didn't help for some reason.

[+stephena]

Good to see at least that Stella is emulating the behaviour correctly.  I suspect that before we added the flow control in version 6.3, it wouldn't have worked at all.