[uart] Add hardware flow control

esphome/components/uart/__init__.py

@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_NUMBER,
     CONF_RX_PIN,
     CONF_TX_PIN,
+    CONF_FLOW_CONTROL_PIN,
     CONF_PORT,
     CONF_UART_ID,
     CONF_DATA,
@@ -116,6 +117,11 @@ def validate_rx_pin(value):
         raise cv.Invalid("Pins GPIO16 and GPIO17 cannot be used as RX pins on ESP8266.")
     return value
 
+def validate_flow_control_support(config):
+    if CONF_FLOW_CONTROL_PIN in config and not CORE.is_esp32:
+        raise cv.Invalid("Hardware does not support flow control.")
+    return config
+
 
 def validate_invert_esp32(config):
     if (
@@ -239,6 +245,7 @@ CONFIG_SCHEMA = cv.All(
             cv.Required(CONF_BAUD_RATE): cv.int_range(min=1),
             cv.Optional(CONF_TX_PIN): pins.internal_gpio_output_pin_schema,
             cv.Optional(CONF_RX_PIN): validate_rx_pin,
+            cv.Optional(CONF_FLOW_CONTROL_PIN): pins.internal_gpio_output_pin_schema,
             cv.Optional(CONF_PORT): cv.All(validate_port, cv.only_on(PLATFORM_HOST)),
             cv.Optional(CONF_RX_BUFFER_SIZE, default=256): cv.validate_bytes,
             cv.Optional(CONF_STOP_BITS, default=1): cv.one_of(1, 2, int=True),
@@ -254,6 +261,7 @@ CONFIG_SCHEMA = cv.All(
     ).extend(cv.COMPONENT_SCHEMA),
     cv.has_at_least_one_key(CONF_TX_PIN, CONF_RX_PIN, CONF_PORT),
     validate_invert_esp32,
+    validate_flow_control_support,
     validate_host_config,
 )
 
@@ -296,6 +304,9 @@ async def to_code(config):
     if CONF_RX_PIN in config:
         rx_pin = await cg.gpio_pin_expression(config[CONF_RX_PIN])
         cg.add(var.set_rx_pin(rx_pin))
+    if CONF_FLOW_CONTROL_PIN in config:
+        flow_control_pin = await cg.gpio_pin_expression(config[CONF_FLOW_CONTROL_PIN])
+        cg.add(var.set_flow_control_pin(flow_control_pin))
     if CONF_PORT in config:
         cg.add(var.set_name(config[CONF_PORT]))
     cg.add(var.set_rx_buffer_size(config[CONF_RX_BUFFER_SIZE]))

esphome/components/uart/uart_component.h

@@ -82,6 +82,10 @@ class UARTComponent {
   // @param rx_pin Pointer to the internal GPIO pin used for reception.
   void set_rx_pin(InternalGPIOPin *rx_pin) { this->rx_pin_ = rx_pin; }
 
+  // Sets the flow control pin for the UART bus.
+  // @param rx_pin Pointer to the internal GPIO pin used for reception.
+  void set_flow_control_pin(InternalGPIOPin *flow_control_pin) { this->flow_control_pin_ = flow_control_pin; }
+
   // Sets the size of the RX buffer.
   // @param rx_buffer_size Size of the RX buffer in bytes.
   void set_rx_buffer_size(size_t rx_buffer_size) { this->rx_buffer_size_ = rx_buffer_size; }
@@ -161,6 +165,7 @@ class UARTComponent {
 
   InternalGPIOPin *tx_pin_;
   InternalGPIOPin *rx_pin_;
+  InternalGPIOPin *flow_control_pin_;
   size_t rx_buffer_size_;
   uint32_t baud_rate_;
   uint8_t stop_bits_;

esphome/components/uart/uart_component_esp32_arduino.cpp

@@ -141,6 +141,10 @@ void ESP32ArduinoUARTComponent::load_settings(bool dump_config) {
     invert = true;
   this->hw_serial_->setRxBufferSize(this->rx_buffer_size_);
   this->hw_serial_->begin(this->baud_rate_, get_config(), rx, tx, invert);
+  if (this->flow_control_pin_ != nullptr) {
+    this->hw_serial_->setPins(-1, -1, -1, this->flow_control_pin_->get_pin());
+    this->hw_serial_->setMode(UART_MODE_RS485_HALF_DUPLEX);
+  }
   if (dump_config) {
     ESP_LOGCONFIG(TAG, "UART %u was reloaded.", this->number_);
     this->dump_config();
@@ -151,6 +155,7 @@ void ESP32ArduinoUARTComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "UART Bus %d:", this->number_);
   LOG_PIN("  TX Pin: ", tx_pin_);
   LOG_PIN("  RX Pin: ", rx_pin_);
+  LOG_PIN("  Flow Control Pin: ", flow_control_pin_);
   if (this->rx_pin_ != nullptr) {
     ESP_LOGCONFIG(TAG, "  RX Buffer Size: %u", this->rx_buffer_size_);
   }

esphome/components/uart/uart_component_esp_idf.cpp

@@ -106,6 +106,7 @@ void IDFUARTComponent::setup() {
 
   int8_t tx = this->tx_pin_ != nullptr ? this->tx_pin_->get_pin() : -1;
   int8_t rx = this->rx_pin_ != nullptr ? this->rx_pin_->get_pin() : -1;
+  int8_t flow_control = this->flow_control_pin_ != nullptr ? this->flow_control_pin_->get_pin() : -1;
 
   uint32_t invert = 0;
   if (this->tx_pin_ != nullptr && this->tx_pin_->is_inverted())
@@ -120,7 +121,7 @@ void IDFUARTComponent::setup() {
     return;
   }
 
-  err = uart_set_pin(this->uart_num_, tx, rx, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
+  err = uart_set_pin(this->uart_num_, tx, rx, flow_control, UART_PIN_NO_CHANGE);
   if (err != ESP_OK) {
     ESP_LOGW(TAG, "uart_set_pin failed: %s", esp_err_to_name(err));
     this->mark_failed();
@@ -139,6 +140,15 @@ void IDFUARTComponent::setup() {
     return;
   }
   
+  if (this->flow_control_pin_ != nullptr) {
+    err = uart_set_mode(this->uart_num_, UART_MODE_RS485_HALF_DUPLEX);
+    if (err != ESP_OK) {
+      ESP_LOGW(TAG, "uart_set_mode failed: %s", esp_err_to_name(err));
+      this->mark_failed();
+      return;
+    }
+  }
+
   xSemaphoreGive(this->lock_);
 }
 
@@ -159,6 +169,7 @@ void IDFUARTComponent::dump_config() {
   ESP_LOGCONFIG(TAG, "UART Bus %u:", this->uart_num_);
   LOG_PIN("  TX Pin: ", tx_pin_);
   LOG_PIN("  RX Pin: ", rx_pin_);
+  LOG_PIN("  Flow Control Pin: ", flow_control_pin_);
   if (this->rx_pin_ != nullptr) {
     ESP_LOGCONFIG(TAG, "  RX Buffer Size: %u", this->rx_buffer_size_);
   }