Initial Release

multicore/multicore_fifo_irqs/CMakeLists.txt

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+add_executable(multicore_fifo_irqs
+        multicore_fifo_irqs.c
+        )
+
+target_link_libraries(multicore_fifo_irqs
+        pico_multicore
+        pico_stdlib)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(multicore_fifo_irqs)
+
+# add url via pico_set_program_url
+example_auto_set_url(multicore_fifo_irqs)

multicore/multicore_fifo_irqs/multicore_fifo_irqs.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 "pico/multicore.h"
+#include "hardware/irq.h"
+
+///tag::multicore_fifo_irqs[]
+
+#define FLAG_VALUE1 123
+#define FLAG_VALUE2 321
+
+static int core0_rx_val = 0, core1_rx_val = 0;
+
+void core0_sio_irq() {
+    // Just record the latest entry
+    while (multicore_fifo_rvalid())
+        core0_rx_val = multicore_fifo_pop_blocking();
+
+    multicore_fifo_clear_irq();
+}
+
+void core1_sio_irq() {
+    // Just record the latest entry
+    while (multicore_fifo_rvalid())
+        core1_rx_val = multicore_fifo_pop_blocking();
+
+    multicore_fifo_clear_irq();
+}
+
+void core1_entry() {
+    multicore_fifo_clear_irq();
+    irq_set_exclusive_handler(SIO_IRQ_PROC1, core1_sio_irq);
+
+    irq_set_enabled(SIO_IRQ_PROC1, true);
+
+    // Send something to Core0, this should fire the interrupt.
+    multicore_fifo_push_blocking(FLAG_VALUE1);
+
+    while (1)
+        tight_loop_contents();
+}
+
+
+int main() {
+    stdio_init_all();
+    printf("Hello, multicore_fifo_irqs!\n");
+
+    // We MUST start the other core before we enabled FIFO interrupts.
+    // This is because the launch uses the FIFO's, enabling interrupts before
+    // they are used for the launch will result in unexpected behaviour.
+    multicore_launch_core1(core1_entry);
+
+    irq_set_exclusive_handler(SIO_IRQ_PROC0, core0_sio_irq);
+    irq_set_enabled(SIO_IRQ_PROC0, true);
+
+    // Wait for a bit for things to happen
+    sleep_ms(10);
+
+    // Send something back to the other core
+    multicore_fifo_push_blocking(FLAG_VALUE2);
+
+    // Wait for a bit for things to happen
+    sleep_ms(10);
+
+    printf("Irq handlers should have rx'd some stuff - core 0 got %d, core 1 got %d!\n", core0_rx_val, core1_rx_val);
+
+    while (1)
+        tight_loop_contents();
+}
+
+///end::multicore_fifo_irqs[]