Initial Release

dma/hello_dma/hello_dma.c

@@ -0,0 +1,49 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+// Use the DMA to copy data between two buffers in memory.
+
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "hardware/dma.h"
+
+// Data will be copied from src to dst
+const char src[] = "Hello, world! (from DMA)";
+char dst[count_of(src)];
+
+int main() {
+    stdio_init_all();
+
+    // Get a free channel, panic() if there are none
+    int chan = dma_claim_unused_channel(true);
+
+    // 8 bit transfers. Both read and write address increment after each
+    // transfer (each pointing to a location in src or dst respectively).
+    // No DREQ is selected, so the DMA transfers as fast as it can.
+
+    dma_channel_config c = dma_channel_get_default_config(chan);
+    channel_config_set_transfer_data_size(&c, DMA_SIZE_8);
+    channel_config_set_read_increment(&c, true);
+    channel_config_set_write_increment(&c, true);
+
+    dma_channel_configure(
+        chan,          // Channel to be configured
+        &c,            // The configuration we just created
+        dst,           // The initial write address
+        src,           // The initial read address
+        count_of(src), // Number of transfers; in this case each is 1 byte.
+        true           // Start immediately.
+    );
+
+    // We could choose to go and do something else whilst the DMA is doing its
+    // thing. In this case the processor has nothing else to do, so we just
+    // wait for the DMA to finish.
+    dma_channel_wait_for_finish_blocking(chan);
+
+    // The DMA has now copied our text from the transmit buffer (src) to the
+    // receive buffer (dst), so we can print it out from there.
+    puts(dst);
+}