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arch/arm/src/stm32l4: fix baud rate setting for LPUART 

Signed-off-by: Juha Niskanen <juha.niskanen@haltian.com>
This commit is contained in:
Juha Niskanen 2021-09-13 17:56:43 +03:00 committed by David Sidrane
parent 7e3c813346
commit 4487b352c0
2 changed files with 77 additions and 8 deletions
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8
arch/arm/src/stm32l4/hardware/stm32l4_uart.h
View File

@ -219,13 +219,19 @@
#define USART_CR3_WUFIE (1 << 22) /* Bit 22: Wakeup from Stop mode interrupt enable */
/* Baud Rate Register */
/* Baud Rate Register (USART) */
#define USART_BRR_FRAC_SHIFT (0) /* Bits 3-0: fraction of USARTDIV */
#define USART_BRR_FRAC_MASK (0x0f << USART_BRR_FRAC_SHIFT)
#define USART_BRR_MANT_SHIFT (4) /* Bits 15-4: mantissa of USARTDIV */
#define USART_BRR_MANT_MASK (0x0fff << USART_BRR_MANT_SHIFT)
/* Baud Rate Register (LPUART) */
#define LPUART_BRR_SHIFT (0) /* Bits 19-0: LPUART baud rate */
#define LPUART_BRR_MASK (0xfffff << LPUART_BRR_SHIFT)
#define LPUART_BRR_MIN (0x300) /* Minimum value permitted for BRR register */
/* Guard time and prescaler register */
#define USART_GTPR_PSC_SHIFT (0) /* Bits 0-7: Prescaler value */

77
arch/arm/src/stm32l4/stm32l4_serial.c
View File

@ -993,20 +993,16 @@ static int stm32l4serial_dmanextrx(FAR struct stm32l4_serial_s *priv)
#endif
/****************************************************************************
* Name: stm32l4serial_setformat
* Name: stm32l4serial_setbaud_usart
*
* Description:
* Set the serial line format and speed.
* Set the serial line baud rate (standard UART and USART).
*
****************************************************************************/
#ifndef CONFIG_SUPPRESS_UART_CONFIG
static void stm32l4serial_setformat(FAR struct uart_dev_s *dev)
static void stm32l4serial_setbaud_usart(FAR struct stm32l4_serial_s *priv)
{
FAR struct stm32l4_serial_s *priv =
(FAR struct stm32l4_serial_s *)dev->priv;
uint32_t regval;
/* This first implementation is for U[S]ARTs that support oversampling
* by 8 in additional to the standard oversampling by 16.
*/
@ -1062,6 +1058,73 @@ static void stm32l4serial_setformat(FAR struct uart_dev_s *dev)
stm32l4serial_putreg(priv, STM32L4_USART_CR1_OFFSET, cr1);
stm32l4serial_putreg(priv, STM32L4_USART_BRR_OFFSET, brr);
}
#endif
/****************************************************************************
* Name: stm32l4serial_setbaud_lpuart
*
* Description:
* Set the serial line baud rate (LPUART only).
*
****************************************************************************/
#ifndef CONFIG_SUPPRESS_UART_CONFIG
#ifdef CONFIG_STM32L4_LPUART1_SERIALDRIVER
static void stm32l4serial_setbaud_lpuart(FAR struct stm32l4_serial_s *priv)
{
uint32_t brr;
/* The equation is:
*
* baud = 256 * fCK / brr
* brr = 256 * fCK / baud
*
* It is forbidden to write values lower than LPUART_BRR_MIN in
* the LPUART_BRR register. fCK must range from 3 x baud rate to
* 4096 x baud rate.
*/
brr = (((uint64_t)priv->apbclock << 8) + (priv->baud >> 1)) / priv->baud;
brr &= LPUART_BRR_MASK;
if (brr < LPUART_BRR_MIN)
{
brr = LPUART_BRR_MIN;
}
stm32l4serial_putreg(priv, STM32L4_USART_BRR_OFFSET, brr);
}
#endif
#endif
/****************************************************************************
* Name: stm32l4serial_setformat
*
* Description:
* Set the serial line format and speed.
*
****************************************************************************/
#ifndef CONFIG_SUPPRESS_UART_CONFIG
static void stm32l4serial_setformat(FAR struct uart_dev_s *dev)
{
FAR struct stm32l4_serial_s *priv =
(FAR struct stm32l4_serial_s *)dev->priv;
uint32_t regval;
/* Set baud rate */
#ifdef CONFIG_STM32L4_LPUART1_SERIALDRIVER
if (priv->usartbase == STM32L4_LPUART1_BASE)
{
stm32l4serial_setbaud_lpuart(priv);
}
else
#endif
{
stm32l4serial_setbaud_usart(priv);
}
/* Configure parity mode */