Once you have joined the FIFOs, the data path in the other direction disappears. So in your application with FIFOs joined for input, the OSR still exists but the ARM CPU has no way to write to it.
If you are just talking about the common case where you want to put some constants into X or Y or OSR at startup and don't need to change them during execution, then this is no problem: just do the forced execution etc. at the beginning, before you join the FIFOs. If you are going to do the FIFO join with sm_config_set_fifo_join() that means you need to do your register loads before you apply the config with pio_sm_set_config() - so either you need to do your register loads assuming the power-up defaults (for things like autopull, shift direction etc), or else do pio_sm_set_config() twice, setting the fifo join the second time.
If you are just talking about the common case where you want to put some constants into X or Y or OSR at startup and don't need to change them during execution, then this is no problem: just do the forced execution etc. at the beginning, before you join the FIFOs. If you are going to do the FIFO join with sm_config_set_fifo_join() that means you need to do your register loads before you apply the config with pio_sm_set_config() - so either you need to do your register loads assuming the power-up defaults (for things like autopull, shift direction etc), or else do pio_sm_set_config() twice, setting the fifo join the second time.
Statistics: Posted by arg001 — Fri Dec 27, 2024 8:38 pm