pio_blink sample
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Outline
#include <stdio.h>
#include "pico/stdlib.h"
#include "hardware/pio.h"
#include "hardware/clocks.h"
#include "blink.pio.h"
#define PIO_BLINK_LED1_GPIO
#define PIO_BLINK_LED3_GPIO
#define PIO_BLINK_LED3_GPIO
main()
blink_pin_forever(PIO, uint, uint, uint, uint)
Files
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SourceVuRaspberry Pi Pico SDK and Examplespio_blink sampleblink.c
 
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/** * Copyright (c) 2020 Raspberry Pi (Trading) Ltd. * * SPDX-License-Identifier: BSD-3-Clause *//* ... */ #include <stdio.h> #include "pico/stdlib.h" #include "hardware/pio.h" #include "hardware/clocks.h" #include "blink.pio.h" 5 includes void blink_pin_forever(PIO pio, uint sm, uint offset, uint pin, uint freq); // by default flash leds on gpios 3-4 #ifndef PIO_BLINK_LED1_GPIO #define PIO_BLINK_LED1_GPIO 3 #endif // and flash leds on gpios 5-6 // or if the device supports more than 32 gpios, flash leds on 32-33 #ifndef PIO_BLINK_LED3_GPIO #if NUM_BANK0_GPIOS <= 32 #define PIO_BLINK_LED3_GPIO 5 #else #define PIO_BLINK_LED3_GPIO 32 #endif/* ... */ #endif int main() { setup_default_uart(); assert(PIO_BLINK_LED1_GPIO < 31); assert(PIO_BLINK_LED3_GPIO < 31 || PIO_BLINK_LED3_GPIO >= 32); PIO pio[2]; uint sm[2]; uint offset[2]; // Find a free pio and state machine and add the program bool rc = pio_claim_free_sm_and_add_program_for_gpio_range(&blink_program, &pio[0], &sm[0], &offset[0], PIO_BLINK_LED1_GPIO, 2, true); hard_assert(rc); printf("Loaded program at %u on pio %u\n", offset[0], PIO_NUM(pio[0])); // Start led1 flashing blink_pin_forever(pio[0], sm[0], offset[0], PIO_BLINK_LED1_GPIO, 4); // Claim the next state machine and start led2 flashing pio_sm_claim(pio[0], sm[0] + 1); blink_pin_forever(pio[0], sm[0] + 1, offset[0], PIO_BLINK_LED1_GPIO + 1, 3); if (PIO_BLINK_LED3_GPIO >= 32) { // Find a free pio and state machine and add the program rc = pio_claim_free_sm_and_add_program_for_gpio_range(&blink_program, &pio[1], &sm[1], &offset[1], PIO_BLINK_LED3_GPIO, 2, true); printf("Loaded program at %u on pio %u\n", offset[1], PIO_NUM(pio[1])); }if (PIO_BLINK_LED3_GPIO >= 32) { ... } else { // no need to load the program again rc = true; pio[1] = pio[0]; sm[1] = sm[0] + 2; offset[1] = offset[0]; pio_sm_claim(pio[1], sm[1]); }else { ... } hard_assert(rc); // Start led3 flashing blink_pin_forever(pio[1], sm[1], offset[1], PIO_BLINK_LED3_GPIO, 2); // Claim the next state machine and start led4 flashing pio_sm_claim(pio[1], sm[1] + 1); blink_pin_forever(pio[1], sm[1] + 1, offset[1], PIO_BLINK_LED3_GPIO + 1, 1); // free up pio resources pio_sm_unclaim(pio[1], sm[1] + 1); if (PIO_BLINK_LED3_GPIO >= 32) { pio_remove_program_and_unclaim_sm(&blink_program, pio[1], sm[1], offset[1]); }if (PIO_BLINK_LED3_GPIO >= 32) { ... } else { pio_sm_unclaim(pio[1], sm[1]); }else { ... } pio_sm_unclaim(pio[0], sm[0] + 1); pio_remove_program_and_unclaim_sm(&blink_program, pio[0], sm[0], offset[0]); // the program exits but the pio keeps running! printf("All leds should be flashing\n"); }{ ... } void blink_pin_forever(PIO pio, uint sm, uint offset, uint pin, uint freq) { blink_program_init(pio, sm, offset, pin); pio_sm_set_enabled(pio, sm, true); printf("Blinking pin %d at %d Hz\n", pin, freq); // PIO counter program takes 3 more cycles in total than we pass as // input (wait for n + 1; mov; jmp) pio->txf[sm] = (clock_get_hz(clk_sys) / (2 * freq)) - 3; }{ ... }
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