MicroPython Interrupt Guide: Supported & Unsupported Interrupts on Raspberry Pi Pico
Compares MicroPython v1.23.0 and v1.26.0 on RP2040, covering newly supported UART interrupts and trigger events to replace polling.
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1. Peripherals with interrupt function
In previous versions of MicroPython for the Raspberry Pi Pico (taking v1.23.0 as an example), only the following peripherals support interrupt functionality:
It can be seen that MicroPython's SDK does not provide interrupt functions for other peripherals, such as interrupt reception of the serial port, but this does not mean that we cannot use other methods to replace the polling method (using while loop to call UART. any () to determine whether there is data available for reception on the serial port). Instead, we can use methods such as timer-based regular serial port status query, multi-threading, and coroutines to complete the timely reception of serial port data more efficiently and accurately.
In the latest version of MicroPython for Raspberry Pi Pico (taking v1.26.0 as an example), interrupts for the newly added I2CTarget class and UART class are introduced, as shown in the table below:
2. Serial Port Interrupt Related Control Methods
UART. irq () is the core method for configuring serial port interrupts on the Pico. It is used to bind an interrupt handling function to a specified UART instance (such as UART0/UART1). When a preset event (such as receiving a character or an idle receive line) occurs on the serial port, this function will be automatically executed, eliminating the need for the main program to perform polling on the serial port status, thus greatly improving the response efficiency of the serial port.
The serial port interrupt method officially provided is as follows:
For the RP2040 corresponding to the Raspberry Pi Pico (the "RP2" row in the table), the UART interrupt trigger sources it supports are as follows:
IRQ_RXIDLE: Triggered when the RX line is idle after receiving ≥1 character (suitable for processing complete data segments);
IRQ_TXIDLE: It is triggered only when the length of the message to be sent is greater than 5 characters, and there are still 5 characters pending for transmission at the time of triggering;
IRQ_BREAK: Triggered when a Break state on the RX line is detected; after triggering, a valid character must be received before it can be triggered again.
