The simplest way to eliminate jitter is often to use PIO. For example, a PIO state machine could pull a byte out of its FIFO exactly every 2000 system cycles and output that byte on 8 GPIOs. It could be configured to assert an interrupt whenever the FIFO was not full, which could cause an interrupt to handler to retrieve or calculate another byte and push it in to the FIFO. If the system clock was 96MHz, 2000 system cycles = 1/48000 secs. So if you use PIO, potentially the PIO itself could be the timer.
If you want to trigger an interrupt handler to assert 48,000 times per second based on a timer, you could use the main timer peripheral itself, but a difficulty you might run into is that timer counts microseconds and 1/48000 secs is not a whole number of microseconds. Whether that loss of precision is actually important for your project, I don't know.
You could potentially use the PWM peripheral as a timer instead instead. PWM has timers that count system clock cycles rather than microseconds and can periodically assert an interrupt every N system cycles. So, e.g. you could configure the system clock to be 96MHz and have a PWM interrupt assert every system 2000 cycles = 1/48000 secs.
If you just want to stream some bytes from memory to a PIO FIFO or other register without any additional processing, there are also DMA pacing timers to periodically trigger the DMA controller every N system cycles.
If you want to trigger an interrupt handler to assert 48,000 times per second based on a timer, you could use the main timer peripheral itself, but a difficulty you might run into is that timer counts microseconds and 1/48000 secs is not a whole number of microseconds. Whether that loss of precision is actually important for your project, I don't know.
You could potentially use the PWM peripheral as a timer instead instead. PWM has timers that count system clock cycles rather than microseconds and can periodically assert an interrupt every N system cycles. So, e.g. you could configure the system clock to be 96MHz and have a PWM interrupt assert every system 2000 cycles = 1/48000 secs.
If you just want to stream some bytes from memory to a PIO FIFO or other register without any additional processing, there are also DMA pacing timers to periodically trigger the DMA controller every N system cycles.
Statistics: Posted by alastairpatrick — Sat May 04, 2024 7:40 pm