From a1da3ac13605b8ea07e9e63485550a05a8dadf00 Mon Sep 17 00:00:00 2001 From: Song Ruo Jing Date: Mon, 12 Aug 2024 21:50:18 +0800 Subject: [PATCH] fix(uart): eliminated potential glitch on TX at setup if TX signal is inversed Closes https://github.com/espressif/esp-idf/issues/14285 --- components/driver/uart.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/components/driver/uart.c b/components/driver/uart.c index 9b8dcb9c38..8f5e678b73 100644 --- a/components/driver/uart.c +++ b/components/driver/uart.c @@ -650,21 +650,22 @@ esp_err_t uart_set_pin(uart_port_t uart_num, int tx_io_num, int rx_io_num, int r /* In the following statements, if the io_num is negative, no need to configure anything. */ if (tx_io_num >= 0 && !uart_try_set_iomux_pin(uart_num, tx_io_num, SOC_UART_TX_PIN_IDX)) { gpio_hal_iomux_func_sel(GPIO_PIN_MUX_REG[tx_io_num], PIN_FUNC_GPIO); - gpio_set_level(tx_io_num, 1); esp_rom_gpio_connect_out_signal(tx_io_num, UART_PERIPH_SIGNAL(uart_num, SOC_UART_TX_PIN_IDX), 0, 0); + // output enable is set inside esp_rom_gpio_connect_out_signal func after the signal is connected + // (output enabled too early may cause unnecessary level change at the pad) } if (rx_io_num >= 0 && !uart_try_set_iomux_pin(uart_num, rx_io_num, SOC_UART_RX_PIN_IDX)) { gpio_hal_iomux_func_sel(GPIO_PIN_MUX_REG[rx_io_num], PIN_FUNC_GPIO); - gpio_set_pull_mode(rx_io_num, GPIO_PULLUP_ONLY); + gpio_set_pull_mode(rx_io_num, GPIO_PULLUP_ONLY); // This does not consider that RX signal can be read inverted by configuring the hardware (i.e. idle is at low level). However, it is only a weak pullup, the TX at the other end can always drive the line. gpio_set_direction(rx_io_num, GPIO_MODE_INPUT); esp_rom_gpio_connect_in_signal(rx_io_num, UART_PERIPH_SIGNAL(uart_num, SOC_UART_RX_PIN_IDX), 0); } if (rts_io_num >= 0 && !uart_try_set_iomux_pin(uart_num, rts_io_num, SOC_UART_RTS_PIN_IDX)) { gpio_hal_iomux_func_sel(GPIO_PIN_MUX_REG[rts_io_num], PIN_FUNC_GPIO); - gpio_set_direction(rts_io_num, GPIO_MODE_OUTPUT); esp_rom_gpio_connect_out_signal(rts_io_num, UART_PERIPH_SIGNAL(uart_num, SOC_UART_RTS_PIN_IDX), 0, 0); + // output enable is set inside esp_rom_gpio_connect_out_signal func after the signal is connected } if (cts_io_num >= 0 && !uart_try_set_iomux_pin(uart_num, cts_io_num, SOC_UART_CTS_PIN_IDX)) {