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AVR port: UART driver support for devices with multiple UARTs.

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This commit is contained in:
Kelvin Lawson
2010-02-21 18:50:46 +00:00
parent 9a72c96305
commit a09d1d7376
1 changed files with 30 additions and 6 deletions
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36
ports/avr/uart.c
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@@ -21,6 +21,30 @@
#include "atomport-private.h"
#include "uart.h"
/*
* Set register-access macros for the first UART across various Atmega devices.
*/
#ifdef UCSRA
/* Device with single UART */
#define REG_UCSRA UCSRA
#define REG_UCSRB UCSRB
#define REG_UBRRL UBRRL
#define REG_UDR UDR
#define BIT_TXEN TXEN
#define BIT_RXEN RXEN
#define BIT_UDRE UDRE
#else
/* Device with multiple UARTs */
#define REG_UCSRA UCSR0A
#define REG_UCSRB UCSR0B
#define REG_UBRRL UBRR0L
#define REG_UDR UDR0
#define BIT_TXEN TXEN0
#define BIT_RXEN RXEN0
#define BIT_UDRE UDRE0
#endif
/*
* Semaphore for single-threaded access to UART device
*/
@@ -37,12 +61,12 @@ uart_init(uint32_t baudrate)
/* Set up the UART device with the selected baudrate */
#if AVR_CPU_HZ < 2000000UL && defined(U2X)
UCSRA = _BV(U2X); /* improve baud rate error by using 2x clk */
UBRRL = (AVR_CPU_HZ / (8UL * baudrate)) - 1;
REG_UCSRA = _BV(U2X); /* improve baud rate error by using 2x clk */
REG_UBRRL = (AVR_CPU_HZ / (8UL * baudrate)) - 1;
#else
UBRRL = (AVR_CPU_HZ / (16UL * baudrate)) - 1;
REG_UBRRL = (AVR_CPU_HZ / (16UL * baudrate)) - 1;
#endif
UCSRB = _BV(TXEN) | _BV(RXEN); /* tx/rx enable */
REG_UCSRB = _BV(BIT_TXEN) | _BV(BIT_RXEN); /* tx/rx enable */
/* Create a mutex for single-threaded putchar() access */
if (atomMutexCreate (&uart_mutex) != ATOM_OK)
@@ -74,8 +98,8 @@ uart_putchar(char c, FILE *stream)
uart_putchar('\r', stream);
/* Wait until the UART is ready then send the character out */
loop_until_bit_is_set(UCSRA, UDRE);
UDR = c;
loop_until_bit_is_set(REG_UCSRA, BIT_UDRE);
REG_UDR = c;
/* Return mutex access */
atomMutexPut(&uart_mutex);