uart.c
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/*
* Copyright (C) 2016 Leon George
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_cc26x0
* @ingroup drivers_periph_uart
* @{
*
* @file
* @brief Low-level UART driver implementation
*
* @author Leon M. George <leon@georgemail.eu>
*
* @}
*/
#include "cpu.h"
#include "periph/uart.h"
/**
* @brief Bit mask for the fractional part of the baudrate
*/
#define FRAC_BITS (6U)
#define FRAC_MASK (0x3f)
/**
* @brief Get the enable mask depending on enabled HW flow control
*/
#if UART_HW_FLOW_CONTROL
#define ENABLE_MASK (UART_CTSEN | UART_CTL_RTSEN | \
UART_CTL_RXE | UART_CTL_TXE | UART_CTL_UARTEN)
#else
#define ENABLE_MASK (UART_CTL_RXE | UART_CTL_TXE | UART_CTL_UARTEN)
#endif
/**
* @brief allocate memory to store callback functions
*/
static uart_isr_ctx_t ctx[UART_NUMOF];
int uart_init(uart_t uart, uint32_t baudrate, uart_rx_cb_t rx_cb, void *arg)
{
/* make sure the uart device is valid */
if (uart != 0) {
return UART_NODEV;
}
/* enable clocks: serial power domain and UART */
PRCM->PDCTL0SERIAL = 1;
while (!(PRCM->PDSTAT0 & PDSTAT0_SERIAL_ON)) ;
uart_poweron(uart);
/* disable and reset the UART */
UART->CTL = 0;
/* save context */
ctx[0].rx_cb = rx_cb;
ctx[0].arg = arg;
/* configure pins */
IOC->CFG[UART_TX_PIN] = IOCFG_PORTID_UART0_TX;
IOC->CFG[UART_RX_PIN] = (IOCFG_PORTID_UART0_RX | IOCFG_INPUT_ENABLE);
#if UART_HW_FLOW_CONTROL
IOC->CFG[UART_RTS_PIN] = IOCFG_PORTID_UART0_RTS;
IOC->CFG[UART_CTS_PIN] = (IOCFG_PORTID_UART0_CTS | IOCFG_INPUT_ENABLE);
#endif
/* calculate baud-rate */
uint32_t tmp = (CLOCK_CORECLOCK * 4);
tmp += (baudrate / 2);
tmp /= baudrate;
UART->IBRD = (tmp >> FRAC_BITS);
UART->FBRD = (tmp & FRAC_MASK);
/* configure line to 8N1 mode, LRCH must be written after IBRD and FBRD! */
UART->LCRH = UART_LCRH_WLEN_8;
/* enable the RX interrupt */
UART->IMSC = UART_IMSC_RXIM;
NVIC_EnableIRQ(UART0_IRQN);
/* start the UART */
UART->CTL = ENABLE_MASK;
return UART_OK;
}
void uart_write(uart_t uart, const uint8_t *data, size_t len)
{
for (size_t i = 0; i < len; i++) {
while (UART->FR & UART_FR_TXFF) {}
UART->DR = data[i];
}
}
void uart_poweron(uart_t uart)
{
PRCM->UARTCLKGR = 1;
PRCM->CLKLOADCTL = CLKLOADCTL_LOAD;
while (!(PRCM->CLKLOADCTL & CLKLOADCTL_LOADDONE)) {}
UART->CTL = ENABLE_MASK;
}
void uart_poweroff(uart_t uart)
{
UART->CTL = 0;
PRCM->UARTCLKGR = 0;
PRCM->CLKLOADCTL = CLKLOADCTL_LOAD;
while (!(PRCM->CLKLOADCTL & CLKLOADCTL_LOADDONE)) {}
}
void isr_uart(void)
{
/* remember pending interrupts */
uint32_t mis = UART->MIS;
/* clear them */
UART->ICR = mis;
/* read received byte and pass it to the RX callback */
if (mis & UART_MIS_RXMIS) {
ctx[0].rx_cb(ctx[0].arg, (uint8_t)UART->DR);
}
cortexm_isr_end();
}