Initial Release

pio/pio_blink/CMakeLists.txt

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+add_executable(pio_blink)
+
+# by default the header is generated into the build dir
+pico_generate_pio_header(pio_blink ${CMAKE_CURRENT_LIST_DIR}/blink.pio)
+# however, alternatively you can choose to generate it somewhere else (in this case in the source tree for check in)
+#pico_generate_pio_header(pio_blink ${CMAKE_CURRENT_LIST_DIR}/blink.pio OUTPUT_DIR ${CMAKE_CURRENT_LIST_DIR})
+
+target_sources(pio_blink PRIVATE blink.c)
+
+target_link_libraries(pio_blink PRIVATE pico_stdlib hardware_pio)
+pico_add_extra_outputs(pio_blink)
+
+# add url via pico_set_program_url
+example_auto_set_url(pio_blink)

pio/pio_blink/blink.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 "blink.pio.h"
+
+void blink_pin_forever(PIO pio, uint sm, uint offset, uint pin, uint freq);
+
+int main() {
+    setup_default_uart();
+
+    // todo get free sm
+    PIO pio = pio0;
+    uint offset = pio_add_program(pio, &blink_program);
+    printf("Loaded program at %d\n", offset);
+
+    blink_pin_forever(pio, 0, offset, 0, 3);
+    blink_pin_forever(pio, 1, offset, 6, 4);
+    blink_pin_forever(pio, 2, offset, 11, 1);
+}
+
+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 freq %d\n", pin, freq);
+    pio->txf[sm] = 24000000 / freq;
+}

pio/pio_blink/blink.pio

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+;
+; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+;
+; SPDX-License-Identifier: BSD-3-Clause
+;
+
+; SET pin 0 should be mapped to your LED GPIO
+
+.program blink
+    pull block
+    out y, 32
+.wrap_target
+    mov x, y
+    set pins, 1   ; Turn LED on
+lp1:
+    jmp x-- lp1   ; Delay for (x + 1) cycles, x is a 32 bit number
+    mov x, y
+    set pins, 0   ; Turn LED off
+lp2:
+    jmp x-- lp2   ; Delay for the same number of cycles again
+.wrap             ; Blink forever!
+
+
+% c-sdk {
+// this is a raw helper function for use by the user which sets up the GPIO output, and configures the SM to output on a particular pin
+
+void blink_program_init(PIO pio, uint sm, uint offset, uint pin) {
+   pio_gpio_init(pio, pin);
+   pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
+   pio_sm_config c = blink_program_get_default_config(offset);
+   sm_config_set_set_pins(&c, pin, 1);
+   pio_sm_init(pio, sm, offset, &c);
+}
+%}