diff --git a/esphome/components/uart/uart_component_esp_idf.cpp b/esphome/components/uart/uart_component_esp_idf.cpp index 6c242220a6..ea7a09fee6 100644 --- a/esphome/components/uart/uart_component_esp_idf.cpp +++ b/esphome/components/uart/uart_component_esp_idf.cpp @@ -19,6 +19,13 @@ namespace esphome::uart { static const char *const TAG = "uart.idf"; +/// Check if a pin number matches one of the default UART0 GPIO pins. +/// These pins may have residual state from the boot console that requires +/// explicit reset before UART reconfiguration (ESP-IDF issue #17459). +static constexpr bool is_default_uart0_pin(int8_t pin_num) { + return pin_num == U0TXD_GPIO_NUM || pin_num == U0RXD_GPIO_NUM; +} + uart_config_t IDFUARTComponent::get_config_() { uart_parity_t parity = UART_PARITY_DISABLE; if (this->parity_ == UART_CONFIG_PARITY_EVEN) { @@ -150,20 +157,26 @@ void IDFUARTComponent::load_settings(bool dump_config) { // Commit 9ed617fb17 removed gpio_func_sel() calls from uart_set_pin(), which breaks // UART on default UART0 pins that may have residual state from boot console. // Reset these pins before configuring UART to ensure they're in a clean state. - if (tx == U0TXD_GPIO_NUM || tx == U0RXD_GPIO_NUM) { + if (is_default_uart0_pin(tx)) { gpio_reset_pin(static_cast(tx)); } - if (rx == U0TXD_GPIO_NUM || rx == U0RXD_GPIO_NUM) { + if (is_default_uart0_pin(rx)) { gpio_reset_pin(static_cast(rx)); } - // Setup pins after reset to preserve open drain/pullup/pulldown flags + // Setup pins after reset to configure GPIO direction and pull resistors. + // For UART0 default pins, setup() must always be called because gpio_reset_pin() + // above sets GPIO_MODE_DISABLE which disables the input buffer. Without setup(), + // uart_set_pin() on ESP-IDF 5.4.2+ does not re-enable the input buffer for + // IOMUX-connected pins, so the RX pin cannot receive data (see issue #10132). + // For other pins, only call setup() if pull or open-drain flags are set to avoid + // disturbing the default pin state which breaks some external components (#11823). auto setup_pin_if_needed = [](InternalGPIOPin *pin) { if (!pin) { return; } const auto mask = gpio::Flags::FLAG_OPEN_DRAIN | gpio::Flags::FLAG_PULLUP | gpio::Flags::FLAG_PULLDOWN; - if ((pin->get_flags() & mask) != gpio::Flags::FLAG_NONE) { + if (is_default_uart0_pin(pin->get_pin()) || (pin->get_flags() & mask) != gpio::Flags::FLAG_NONE) { pin->setup(); } };