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README.md 1.16 KiB

Systick IRQ demonstration

This example shows how to set up the built-in Systick IRQ to generate periodic interrupts for timing. Many bare-metal and RTOS based embedded applications will use the Systick IRQ for timing, periodic housekeeping and task arbitration so knowing how to set that up is useful.

Note that this example is NOT compatible with the Delay_*() functions that are part of the ch32v003fun library - those functions use the Systick counter for doing busy-wait delays and assume that the CNT register rolls over at 32-bit maximum. Do not use the built-in Delay_Ms() and related functions when using Systick for IRQs.

Note also the use of the __attribute__((interrupt)) syntax in declaring the IRQ handler. Some of the IRQ examples from the WCH HAL library have slightly different syntax to make use of a fast IRQ mode but which is not compatible with generic RISC-V GCC so that feature is not used here.

Use

Connect LEDs (with proper current limit resistors) to GPIO pins C0, D0, D4 and a 3.3V logic level serial terminal to PD5. The LEDs will flash and an incrementing count will be printed to the serial port at rates that are controlled by the Systick IRQ.