Initial Release

pio/pwm/pwm.c

@@ -0,0 +1,46 @@
+/**
+ * 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 "pwm.pio.h"
+
+// Write `period` to the input shift register
+void pio_pwm_set_period(PIO pio, uint sm, uint32_t period) {
+    pio_sm_set_enabled(pio, sm, false);
+    pio_sm_put_blocking(pio, sm, period);
+    pio_sm_exec(pio, sm, pio_encode_pull(false, false));
+    pio_sm_exec(pio, sm, pio_encode_out(pio_isr, 32));
+    pio_sm_set_enabled(pio, sm, true);
+}
+
+// Write `level` to TX FIFO. State machine will copy this into X.
+void pio_pwm_set_level(PIO pio, uint sm, uint32_t level) {
+    pio_sm_put_blocking(pio, sm, level);
+}
+
+int main() {
+    stdio_init_all();
+
+    // todo get free sm
+    PIO pio = pio0;
+    int sm = 0;
+    uint offset = pio_add_program(pio, &pwm_program);
+    printf("Loaded program at %d\n", offset);
+
+    pwm_program_init(pio, sm, offset, 25);
+    pio_pwm_set_period(pio, sm, (1u << 16) - 1);
+
+    int level = 0;
+    while (true) {
+        printf("Level = %d\n", level);
+        pio_pwm_set_level(pio, sm, level * level);
+        level = (level + 1) % 256;
+        sleep_ms(10);
+    }
+}