Add function to control UART FIFO trigger levels #719
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kilograham
reviewed
Sep 13, 2022
| * \param tx_level Transmit interrupt FIFO level select | ||
| */ | ||
| static inline void uart_set_irq_fifo_levels(uart_inst_t *uart, uart_fifo_level_t rx_level, uart_fifo_level_t tx_level) { | ||
| hw_write_masked(&uart_get_hw(uart)->ifls, rx_level << UART_UARTIFLS_RXIFLSEL_LSB, UART_UARTIFLS_RXIFLSEL_BITS); |
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seems like you could do this in one hw_write_masked
SPMThePlayer
approved these changes
Nov 1, 2024
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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_enablesfunction, where it is set to the minimum value. I wrote a functionuart_set_irq_fifo_levelsto 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_enablesresets them to 1/8, so every time that function is calleduart_set_irq_fifo_levelsmust be called again to set the chosen values. This could potentially be fixed by removing the lines inuart_set_irq_enablesthat 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.