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diff --git a/boards/base/RaspberryPi/example-FreeRTOS/Drivers/uart.c b/boards/base/RaspberryPi/example-FreeRTOS/Drivers/uart.c
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+/* uart.c - UART initialization & communication */
+/* Reference material:
+ * http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf
+ * Chapter 13: UART
+ */
+
+#include <stdint.h>
+#include <mmio.h>
+#include <uart.h>
+
+enum {
+ // The GPIO registers base address.
+ GPIO_BASE = 0x20200000,
+
+ // The offsets for reach register.
+
+ // Controls actuation of pull up/down to ALL GPIO pins.
+ GPPUD = (GPIO_BASE + 0x94),
+
+ // Controls actuation of pull up/down for specific GPIO pin.
+ GPPUDCLK0 = (GPIO_BASE + 0x98),
+
+ // The base address for UART.
+ UART0_BASE = 0x20201000,
+
+ // The offsets for reach register for the UART.
+ UART0_DR = (UART0_BASE + 0x00),
+ UART0_RSRECR = (UART0_BASE + 0x04),
+ UART0_FR = (UART0_BASE + 0x18),
+ UART0_ILPR = (UART0_BASE + 0x20),
+ UART0_IBRD = (UART0_BASE + 0x24),
+ UART0_FBRD = (UART0_BASE + 0x28),
+ UART0_LCRH = (UART0_BASE + 0x2C),
+ UART0_CR = (UART0_BASE + 0x30),
+ UART0_IFLS = (UART0_BASE + 0x34),
+ UART0_IMSC = (UART0_BASE + 0x38),
+ UART0_RIS = (UART0_BASE + 0x3C),
+ UART0_MIS = (UART0_BASE + 0x40),
+ UART0_ICR = (UART0_BASE + 0x44),
+ UART0_DMACR = (UART0_BASE + 0x48),
+ UART0_ITCR = (UART0_BASE + 0x80),
+ UART0_ITIP = (UART0_BASE + 0x84),
+ UART0_ITOP = (UART0_BASE + 0x88),
+ UART0_TDR = (UART0_BASE + 0x8C),
+};
+
+/*
+ * delay function
+ * int32_t delay: number of cycles to delay
+ *
+ * This just loops <delay> times in a way that the compiler
+ * wont optimize away.
+ */
+static void delay(int32_t count) {
+ asm volatile("__delay_%=: subs %[count], %[count], #1; bne __delay_%=\n"
+ : : [count]"r"(count) : "cc");
+}
+
+/*
+ * Initialize UART0.
+ */
+void uart_init() {
+ // Disable UART0.
+ mmio_write(UART0_CR, 0x00000000);
+ // Setup the GPIO pin 14 && 15.
+
+ // Disable pull up/down for all GPIO pins & delay for 150 cycles.
+ mmio_write(GPPUD, 0x00000000);
+ delay(150);
+
+ // Disable pull up/down for pin 14,15 & delay for 150 cycles.
+ mmio_write(GPPUDCLK0, (1 << 14) | (1 << 15));
+ delay(150);
+
+ // Write 0 to GPPUDCLK0 to make it take effect.
+ mmio_write(GPPUDCLK0, 0x00000000);
+
+ // Clear pending interrupts.
+ mmio_write(UART0_ICR, 0x7FF);
+
+ // Set integer & fractional part of baud rate.
+ // Divider = UART_CLOCK/(16 * Baud)
+ // Fraction part register = (Fractional part * 64) + 0.5
+ // UART_CLOCK = 3000000; Baud = 115200.
+
+ // Divider = 3000000/(16 * 115200) = 1.627 = ~1.
+ // Fractional part register = (.627 * 64) + 0.5 = 40.6 = ~40.
+ mmio_write(UART0_IBRD, 1);
+ mmio_write(UART0_FBRD, 40);
+
+ // Enable FIFO & 8 bit data transmissio (1 stop bit, no parity).
+ mmio_write(UART0_LCRH, (1 << 4) | (1 << 5) | (1 << 6));
+
+ // Mask all interrupts.
+ mmio_write(UART0_IMSC, (1 << 1) | (1 << 4) | (1 << 5) |
+ (1 << 6) | (1 << 7) | (1 << 8) |
+ (1 << 9) | (1 << 10));
+
+ // Enable UART0, receive & transfer part of UART.
+ mmio_write(UART0_CR, (1 << 0) | (1 << 8) | (1 << 9));
+}
+
+/*
+ * Transmit a byte via UART0.
+ * uint8_t Byte: byte to send.
+ */
+void uart_putc(uint8_t byte) {
+ // wait for UART to become ready to transmit
+ while (1) {
+ if (!(mmio_read(UART0_FR) & (1 << 5))) {
+ break;
+ }
+ }
+ mmio_write(UART0_DR, byte);
+}
+
+/*
+ * print a string to the UART one character at a time
+ * const char *str: 0-terminated string
+ */
+void uart_puts(const char *str) {
+ while (*str) {
+ uart_putc(*str++);
+ }
+}