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cpu/stm32f4: optimized baudrate calculation

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This commit is contained in:
Hauke Petersen 2015-09-18 12:21:46 +02:00
parent d71abdf980
commit d17973a060
1 changed files with 4 additions and 5 deletions
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9
cpu/stm32f4/periph/uart.c
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@ -97,8 +97,7 @@ int uart_init_blocking(uart_t uart, uint32_t baudrate)
uint32_t tx_pin = 0;
uint32_t rx_pin = 0;
uint8_t af = 0;
float clk = 0.0;
float divider;
uint32_t clk = 0;
uint16_t mantissa;
uint8_t fraction;
@ -167,9 +166,9 @@ int uart_init_blocking(uart_t uart, uint32_t baudrate)
}
/* configure UART to mode 8N1 with given baudrate */
divider = clk / (16 * baudrate);
mantissa = (uint16_t)divider;
fraction = (uint8_t)((divider - mantissa) * 16);
clk /= baudrate;
mantissa = (uint16_t)(clk / 16);
fraction = (uint8_t)(clk - (mantissa * 16));
dev->BRR = ((mantissa & 0x0fff) << 4) | (0x0f & fraction);
/* enable receive and transmit mode */