Initial Release

uart/CMakeLists.txt

@@ -0,0 +1,4 @@
+if (NOT PICO_NO_HARDWARE)
+    add_subdirectory(hello_uart)
+    add_subdirectory(uart_advanced)
+endif ()

uart/hello_uart/CMakeLists.txt

@@ -0,0 +1,12 @@
+add_executable(hello_uart
+        hello_uart.c
+        )
+
+# Pull in our pico_stdlib which pulls in commonly used features
+target_link_libraries(hello_uart pico_stdlib)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(hello_uart)
+
+# add url via pico_set_program_url
+example_auto_set_url(hello_uart)

uart/hello_uart/hello_uart.c

@@ -0,0 +1,44 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "hardware/uart.h"
+
+/// \tag::hello_uart[]
+
+#define UART_ID uart0
+#define BAUD_RATE 115200
+
+// We are using pins 0 and 1, but see the GPIO function select table in the
+// datasheet for information on which other pins can be used.
+#define UART_TX_PIN 0
+#define UART_RX_PIN 1
+
+int main() {
+    // Set up our UART with the required speed.
+    uart_init(UART_ID, BAUD_RATE);
+
+    // Set the TX and RX pins by using the function select on the GPIO
+    // Set datasheet for more information on function select
+    gpio_set_function(UART_TX_PIN, GPIO_FUNC_UART);
+    gpio_set_function(UART_RX_PIN, GPIO_FUNC_UART);
+
+    // Use some the various UART functions to send out data
+    // In a default system, printf will also output via the default UART
+
+    // Send out a character without any conversions
+    uart_putc_raw(UART_ID, 'A');
+
+    // Send out a character but do CR/LF conversions
+    uart_putc(UART_ID, 'B');
+
+    // Send out a string, with CR/LF conversions
+    uart_puts(UART_ID, " Hello, UART!\n");
+}
+
+/// \end::hello_uart[]

uart/uart_advanced/CMakeLists.txt

@@ -0,0 +1,12 @@
+add_executable(uart_advanced
+        uart_advanced.c
+        )
+
+# Pull in our pico_stdlib which pulls in commonly used features
+target_link_libraries(uart_advanced pico_stdlib hardware_uart)
+
+# create map/bin/hex file etc.
+pico_add_extra_outputs(uart_advanced)
+
+# add url via pico_set_program_url
+example_auto_set_url(uart_advanced)

uart/uart_advanced/uart_advanced.c

@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+
+#include "pico/stdlib.h"
+#include "hardware/uart.h"
+#include "hardware/irq.h"
+
+
+/// \tag::uart_advanced[]
+
+#define UART_ID uart0
+#define BAUD_RATE 115200
+#define DATA_BITS 8
+#define STOP_BITS 1
+#define PARITY    UART_PARITY_NONE
+
+// We are using pins 0 and 1, but see the GPIO function select table in the
+// datasheet for information on which other pins can be used.
+#define UART_TX_PIN 0
+#define UART_RX_PIN 1
+
+static int chars_rxed = 0;
+
+// RX interrupt handler
+void on_uart_rx() {
+    while (uart_is_readable(UART_ID)) {
+        uint8_t ch = uart_getc(UART_ID);
+        // Can we send it back?
+        if (uart_is_writable(UART_ID)) {
+            // Change it slightly first!
+            ch++;
+            uart_putc(UART_ID, ch);
+        }
+        chars_rxed++;
+    }
+}
+
+int main() {
+    // Set up our UART with a basic baud rate.
+    uart_init(UART_ID, 2400);
+
+    // Set the TX and RX pins by using the function select on the GPIO
+    // Set datasheet for more information on function select
+    gpio_set_function(UART_TX_PIN, GPIO_FUNC_UART);
+    gpio_set_function(UART_RX_PIN, GPIO_FUNC_UART);
+
+    // Actually, we want a different speed
+    // The call will return the actual baud rate selected, which will be as close as
+    // possible to that requested
+    int actual = uart_set_baudrate(UART_ID, BAUD_RATE);
+
+    // Set UART flow control CTS/RTS, we don't want these, so turn them off
+    uart_set_hw_flow(UART_ID, false, false);
+
+    // Set our data format
+    uart_set_format(UART_ID, DATA_BITS, STOP_BITS, PARITY);
+
+    // Turn off FIFO's - we want to do this character by character
+    uart_set_fifo_enabled(UART_ID, false);
+
+    // Set up a RX interrupt
+    // We need to set up the handler first
+    // Select correct interrupt for the UART we are using
+    int UART_IRQ = UART_ID == uart0 ? UART0_IRQ : UART1_IRQ;
+
+    // And set up and enable the interrupt handlers
+    irq_set_exclusive_handler(UART_IRQ, on_uart_rx);
+    irq_set_enabled(UART_IRQ, true);
+
+    // Now enable the UART to send interrupts - RX only
+    uart_set_irq_enables(UART_ID, true, false);
+
+    // OK, all set up.
+    // Lets send a basic string out, and then run a loop and wait for RX interrupts
+    // The handler will count them, but also reflect the incoming data back with a slight change!
+    uart_puts(UART_ID, "\nHello, uart interrupts\n");
+
+    while (1)
+        tight_loop_contents();
+}
+
+/// \end:uart_advanced[]