Initial Release

pio/hello_pio/CMakeLists.txt

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+add_executable(hello_pio)
+
+pico_generate_pio_header(hello_pio ${CMAKE_CURRENT_LIST_DIR}/hello.pio)
+
+target_sources(hello_pio PRIVATE hello.c)
+
+target_link_libraries(hello_pio PRIVATE
+        pico_stdlib
+        hardware_pio
+        )
+
+pico_add_extra_outputs(hello_pio)
+
+# add url via pico_set_program_url
+example_auto_set_url(hello_pio)

pio/hello_pio/hello.c

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+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "pico/stdlib.h"
+#include "hardware/pio.h"
+// Our assembled program:
+#include "hello.pio.h"
+
+int main() {
+    // Choose which PIO instance to use (there are two instances)
+    PIO pio = pio0;
+
+    // Our assembled program needs to be loaded into this PIO's instruction
+    // memory. This SDK function will find a location (offset) in the
+    // instruction memory where there is enough space for our program. We need
+    // to remember this location!
+    uint offset = pio_add_program(pio, &hello_program);
+
+    // Find a free state machine on our chosen PIO (erroring if there are
+    // none). Configure it to run our program, and start it, using the
+    // helper function we included in our .pio file.
+    uint sm = pio_claim_unused_sm(pio, true);
+    hello_program_init(pio, sm, offset, PICO_DEFAULT_LED_PIN);
+
+    // The state machine is now running. Any value we push to its TX FIFO will
+    // appear on the LED pin.
+    while (true) {
+        // Blink
+        pio_sm_put_blocking(pio, sm, 1);
+        sleep_ms(500);
+        // Blonk
+        pio_sm_put_blocking(pio, sm, 0);
+        sleep_ms(500);
+    }
+}

pio/hello_pio/hello.pio

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+;
+; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+;
+; SPDX-License-Identifier: BSD-3-Clause
+;
+
+.program hello
+
+; Repeatedly get one word of data from the TX FIFO, stalling when the FIFO is
+; empty. Write the least significant bit to the OUT pin group.
+
+loop:
+    pull
+    out pins, 1
+    jmp loop
+
+% c-sdk {
+static inline void hello_program_init(PIO pio, uint sm, uint offset, uint pin) {
+    pio_sm_config c = hello_program_get_default_config(offset);
+
+    // Map the state machine's OUT pin group to one pin, namely the `pin`
+    // parameter to this function.
+    sm_config_set_out_pins(&c, pin, 1);
+    // Set this pin's GPIO function (connect PIO to the pad)
+    pio_gpio_init(pio, pin);
+    // Set the pin direction to output at the PIO
+    pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
+
+    // Load our configuration, and jump to the start of the program
+    pio_sm_init(pio, sm, offset, &c);
+    // Set the state machine running
+    pio_sm_set_enabled(pio, sm, true);
+}
+%}