Add function to control UART FIFO trigger levels #719

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nmk456 wants to merge 1 commit from nmk456/develop into develop

nmk456 commented

2022-01-27 12:55:15 -06:00

(Migrated from github.com)

The RP2040 has a register to change the UART FIFO level at which an interrupt will be generated, but this is not exposed in the SDK. The only time it is used is within the uart_set_irq_enables function, where it is set to the minimum value. I wrote a function uart_set_irq_fifo_levels to configure it to any of the possible values (1/8, 1/4, 1/2, 3/4, and 7/8 full).

There is a slight inconvenience that uart_set_irq_enables resets them to 1/8, so every time that function is called uart_set_irq_fifo_levels must be called again to set the chosen values. This could potentially be fixed by removing the lines in uart_set_irq_enables that does this, but I didn't want to change the functionality of an existing function to keep backwards compatibility.

I wrote some code to test this function, which can be found here, along with it's output.

The RP2040 has a register to change the UART FIFO level at which an interrupt will be generated, but this is not exposed in the SDK. The only time it is used is within the `uart_set_irq_enables` function, where it is set to the minimum value. I wrote a function `uart_set_irq_fifo_levels` to configure it to any of the possible values (1/8, 1/4, 1/2, 3/4, and 7/8 full). There is a slight inconvenience that `uart_set_irq_enables` resets them to 1/8, so every time that function is called `uart_set_irq_fifo_levels` must be called again to set the chosen values. This could potentially be fixed by removing the lines in `uart_set_irq_enables` that does this, but I didn't want to change the functionality of an existing function to keep backwards compatibility. I wrote some code to test this function, which can be found [here](https://gist.github.com/nmk456/68e56a52dfa75990f447cc9a9be18c30), along with it's output.

lurch commented

2022-01-27 15:37:49 -06:00

(Migrated from github.com)

I'm not sure if they're relevant to your change here, but see also #548 and #500 and #568

kilograham (Migrated from github.com) reviewed

2022-09-13 09:41:49 -05:00

src/rp2_common/hardware_uart/include/hardware/uart.h

seems like you could do this in one hw_write_masked

seems like you could do this in one `hw_write_masked`

SPMThePlayer (Migrated from github.com) approved these changes

2024-11-01 02:24:06 -05:00

This pull request has changes conflicting with the target branch.

src/rp2_common/hardware_uart/include/hardware/uart.h

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Merge pull request 'Add function to control UART FIFO trigger levels' (#719) from nmk456/develop into develop

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Reviewed-on: https://git.richey.dev/gh-raspberrypi/pico-sdk/pulls/719

Merge pull request 'Add function to control UART FIFO trigger levels' (#719) from nmk456/develop into develop

Reviewed-on: https://git.richey.dev/gh-raspberrypi/pico-sdk/pulls/719

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