From: Frank M. H. <fm...@gm...> - 2019-07-31 23:09:38
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I found a detailed manual for the tms9914a online, and it has a diagram for the controller state machine. If it is accurate, it could explain the behavior. It shows if the chip is given a tcs command, it transitions from CSBS to CWAS. Then it waits for ANRS to complete the transition to CSHS. The problem is, while in CWAS it ignores tca. So if a synchronous tcs is issued but never completes due to the acceptor not ready state (ANRS) never happening, then tca won't have any effect. The only workaround I see would be to never use tcs so it can't get stuck in the CWAS state. Also, the datasheet's acceptor handshake diagram shows transitions to ANRS when the rhdf command is issued or the data in register is read, so that could explain why they ungum things, since ANRS allows the take control synchronously to complete. |