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Merge pull request #596 from hexluthor/cc2538-uart-baudrate 

cc2538: Support any UART baudrate.
This commit is contained in:
George Oikonomou 2014-04-13 02:51:58 +01:00
parent dbb8f3ec13 336224633a
commit 22554e6d72
3 changed files with 18 additions and 53 deletions
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7
cpu/cc2538/dev/uart.c
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@ -92,7 +92,7 @@ reset(void)
uint32_t lchr;
/* Make sure the UART is disabled before trying to configure it */
REG(UART_BASE | UART_CTL) = UART_CTL_TXE | UART_CTL_RXE;
REG(UART_BASE | UART_CTL) = UART_CTL_VALUE;
/* Clear error status */
REG(UART_BASE | UART_ECR) = 0xFF;
@ -165,11 +165,10 @@ uart_init(void)
UART_IFLS_RXIFLSEL_1_8 | UART_IFLS_TXIFLSEL_1_2;
/* Make sure the UART is disabled before trying to configure it */
REG(UART_BASE | UART_CTL) = UART_CTL_TXE | UART_CTL_RXE;
REG(UART_BASE | UART_CTL) = UART_CTL_VALUE;
/* Baud Rate Generation */
REG(UART_BASE | UART_IBRD) = UART_CONF_IBRD;
REG(UART_BASE | UART_FBRD) = UART_CONF_FBRD;
uart_set_baudrate(UART_CONF_BAUD_RATE);
/* UART Control: 8N1 with FIFOs */
REG(UART_BASE | UART_LCRH) = UART_LCRH_WLEN_8 | UART_LCRH_FEN;

56
cpu/cc2538/dev/uart.h
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@ -65,50 +65,24 @@
* \name Baud rate defines
*
* Used in uart_init() to set the values of UART_IBRD and UART_FBRD in order to
* achieve some standard baud rates. These defines assume that the UART is
* clocked at 16MHz and that Clock Div is 16 (UART_CTL:HSE clear)
* achieve some standard baud rates.
* @{
*/
#define UART_IBRD_9600 104 /**< IBRD value for baud rate 9600 */
#define UART_FBRD_9600 11 /**< FBRD value for baud rate 9600 */
#define UART_IBRD_38400 26 /**< IBRD value for baud rate 38400 */
#define UART_FBRD_38400 3 /**< FBRD value for baud rate 38400 */
#define UART_IBRD_57600 17 /**< IBRD value for baud rate 57600 */
#define UART_FBRD_57600 24 /**< FBRD value for baud rate 57600 */
#define UART_IBRD_115200 8 /**< IBRD value for baud rate 115200 */
#define UART_FBRD_115200 44 /**< FBRD value for baud rate 115200 */
#define UART_IBRD_230400 4 /**< IBRD value for baud rate 230400 */
#define UART_FBRD_230400 22 /**< FBRD value for baud rate 230400 */
#define UART_IBRD_460800 2 /**< IBRD value for baud rate 460800 */
#define UART_FBRD_460800 11 /**< FBRD value for baud rate 460800 */
#define UART_CLOCK_RATE 16000000 /* 16 MHz */
#define UART_CTL_HSE_VALUE 0
#define UART_CTL_VALUE ( UART_CTL_RXE | UART_CTL_TXE | (UART_CTL_HSE_VALUE << 5) )
/* DIV_ROUND() divides integers while avoiding a rounding error: */
#define DIV_ROUND(num, denom) ( ((num) + (denom) / 2) / (denom) )
#define BAUD2BRD(baud) DIV_ROUND(UART_CLOCK_RATE << (UART_CTL_HSE_VALUE + 2), (baud))
#define uart_set_baudrate(baud) do { \
REG(UART_BASE | UART_IBRD) = BAUD2BRD(baud) >> 6; \
REG(UART_BASE | UART_FBRD) = BAUD2BRD(baud) & 0x3f; \
REG(UART_BASE | UART_LCRH) = REG(UART_BASE | UART_LCRH); \
} while(0)
#if UART_CONF_BAUD_RATE==9600
#define UART_CONF_IBRD UART_IBRD_9600
#define UART_CONF_FBRD UART_FBRD_9600
#elif UART_CONF_BAUD_RATE==38400
#define UART_CONF_IBRD UART_IBRD_38400
#define UART_CONF_FBRD UART_FBRD_38400
#elif UART_CONF_BAUD_RATE==57600
#define UART_CONF_IBRD UART_IBRD_57600
#define UART_CONF_FBRD UART_FBRD_57600
#elif UART_CONF_BAUD_RATE==115200
#define UART_CONF_IBRD UART_IBRD_115200
#define UART_CONF_FBRD UART_FBRD_115200
#elif UART_CONF_BAUD_RATE==230400
#define UART_CONF_IBRD UART_IBRD_230400
#define UART_CONF_FBRD UART_FBRD_230400
#elif UART_CONF_BAUD_RATE==460800
#define UART_CONF_IBRD UART_IBRD_460800
#define UART_CONF_FBRD UART_FBRD_460800
#else /* Bail out with an error unless the user provided custom values */
#if !(defined UART_CONF_IBRD && defined UART_CONF_FBRD)
#error "UART baud rate misconfigured and custom IBRD/FBRD values not provided"
#error "Check the value of UART_CONF_BAUD_RATE in contiki-conf.h or project-conf.h"
#error "Supported values are 9600, 38400, 57600, 115200, 230400 and 460800."
#error "Alternatively, you can provide custom values for "
#error "UART_CONF_IBRD and UART_CONF_FBRD"
#endif
#endif
/** @} */
/*---------------------------------------------------------------------------*/
/** \name UART Register Offsets

8
platform/cc2538dk/README.md
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@ -367,14 +367,6 @@ By default, the CC2538 UART is configured with a baud rate of 115200. It is easy
#define UART_CONF_BAUD_RATE 230400
Currently, this configuration directive only supports values 115200, 230400 and 460800. Custom baud rates can also be achieved by following the steps below:
* Configure `UART_CONF_BAUD_RATE` with an unsupported value to prevent it from auto-choosing values for IBRD and FBRD. For instance, in your project-conf.h you can do:
#define UART_CONF_BAUD_RATE 0
* Provide custom values for `UART_CONF_IBRD` and `UART_CONF_FBRD` according to the guidelines in the CC2538 User Guide.
RF and USB DMA
--------------
Transfers between RAM and the RF and USB will be conducted with DMA. If for whatever reason you wish to disable this, here are the relevant configuration lines.