84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "pico/util/queue.h"
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bool timer_callback(repeating_timer_t *rt);
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queue_t sample_fifo;
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// using struct as an example, but primitive types can be used too
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typedef struct element {
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uint value;
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} element_t;
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const int FIFO_LENGTH = 32;
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int main() {
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stdio_init_all();
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int hz = 25;
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queue_init(&sample_fifo, sizeof(element_t), FIFO_LENGTH);
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repeating_timer_t timer;
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// negative timeout means exact delay (rather than delay between callbacks)
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if (!add_repeating_timer_us(-1000000 / hz, timer_callback, NULL, &timer)) {
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printf("Failed to add timer\n");
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return 1;
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}
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// read some blocking
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for (int i = 0; i < 10; i++) {
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element_t element;
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queue_remove_blocking(&sample_fifo, &element);
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printf("Got %d: %d\n", i, element.value);
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}
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// now retrieve all that are available periodically (simulate polling)
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for (int i = 0; i < 10; i++) {
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int count = queue_get_level(&sample_fifo);
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if (count) {
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printf("Getting %d, %d:\n", i, count);
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for (; count > 0; count--) {
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element_t element;
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queue_remove_blocking(&sample_fifo, &element);
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printf(" got %d\n", element.value);
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}
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}
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sleep_us(5000000 / hz); // sleep for 5 times the sampling period
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}
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cancel_repeating_timer(&timer);
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// drain any remaining
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element_t element;
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while (queue_try_remove(&sample_fifo, &element)) {
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printf("Got remaining %d\n", element.value);
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}
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queue_free(&sample_fifo);
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printf("Done\n");
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return 0;
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}
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bool timer_callback(repeating_timer_t *rt) {
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static int v = 100;
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element_t element = {
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.value = v
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};
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v += 100;
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if (!queue_try_add(&sample_fifo, &element)) {
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printf("FIFO was full\n");
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}
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return true; // keep repeating
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}
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