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Unconfigure GPIO pins when closing a serial port to prevent back effects from back-powering on the TX pin. From Kosma Moczek

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This commit is contained in:
Gregory Nutt 2014-06-30 08:02:26 -06:00
parent dd8bb71cbc
commit 292d2a1c1f
1 changed files with 32 additions and 0 deletions
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32
arch/arm/src/stm32/stm32_serial.c
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@ -1594,6 +1594,38 @@ static void up_shutdown(struct uart_dev_s *dev)
regval = up_serialin(priv, STM32_USART_CR1_OFFSET);
regval &= ~(USART_CR1_UE | USART_CR1_TE | USART_CR1_RE);
up_serialout(priv, STM32_USART_CR1_OFFSET, regval);
/* Release pins. "If the serial-attached device is powered down, the TX
* pin causes back-powering, potentially confusing the device to the point
* of complete lock-up."
*
* REVISIT: Is unconfiguring the pins appropriate for all device? If not,
* then this may need to be a configuration option.
*/
stm32_unconfiggpio(priv->tx_gpio);
stm32_unconfiggpio(priv->rx_gpio);
#ifdef CONFIG_SERIAL_OFLOWCONTROL
if (priv->cts_gpio != 0)
{
stm32_unconfiggpio(priv->cts_gpio);
}
#endif
#ifdef CONFIG_SERIAL_IFLOWCONTROL
if (priv->rts_gpio != 0)
{
stm32_unconfiggpio(priv->rts_gpio);
}
#endif
#if HAVE_RS485
if (priv->rs485_dir_gpio != 0)
{
stm32_unconfiggpio(priv->rs485_dir_gpio);
}
#endif
}
/****************************************************************************