Adds HardwareSerial::setTxBufferSize() (#6383)

* Adds HardwareSerial::setTxBufferSize()

* uartBegin def fix

* checks TXBufferSize  as defined in IDF

Makes sure that the buffer size will not cause a reset to the board.

* Removes double value in Rx/Tx Buffer Size 

Keeps Rx/Tx buffer size as set, not doubling it. It makes the process more clear.
Co-authored-by: Rodrigo Garcia <rodrigo.garcia@espressif.com>

cores/esp32/HardwareSerial.cpp

@@ -128,6 +128,7 @@ HardwareSerial::HardwareSerial(int uart_nr) :
 _uart_nr(uart_nr), 
 _uart(NULL), 
 _rxBufferSize(256),
+_txBufferSize(0), 
 _onReceiveCB(NULL), 
 _onReceiveErrorCB(NULL),
 _eventTask(NULL)
@@ -295,7 +296,7 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
     }
 
     // IDF UART driver keeps Pin setting on restarting. Negative Pin number will keep it unmodified.
-    _uart = uartBegin(_uart_nr, baud ? baud : 9600, config, rxPin, txPin, _rxBufferSize, invert, rxfifo_full_thrhd);
+    _uart = uartBegin(_uart_nr, baud ? baud : 9600, config, rxPin, txPin, _rxBufferSize, _txBufferSize, invert, rxfifo_full_thrhd);
     if (!baud) {
         // using baud rate as zero, forces it to try to detect the current baud rate in place
         uartStartDetectBaudrate(_uart);
@@ -309,7 +310,7 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
 
         if(detectedBaudRate) {
             delay(100); // Give some time...
-            _uart = uartBegin(_uart_nr, detectedBaudRate, config, rxPin, txPin, _rxBufferSize, invert, rxfifo_full_thrhd);
+            _uart = uartBegin(_uart_nr, detectedBaudRate, config, rxPin, txPin, _rxBufferSize, _txBufferSize, invert, rxfifo_full_thrhd);
         } else {
             log_e("Could not detect baudrate. Serial data at the port must be present within the timeout for detection to be possible");
             _uart = NULL;
@@ -458,10 +459,26 @@ size_t HardwareSerial::setRxBufferSize(size_t new_size) {
     }
 
     if (new_size <= SOC_UART_FIFO_LEN) {
-        log_e("RX Buffer must be higher than %d.\n", SOC_UART_FIFO_LEN);
+        log_e("RX Buffer must be higher than %d.\n", SOC_UART_FIFO_LEN);  // ESP32, S2, S3 and C3 means higher than 128
         return 0;
     }
 
     _rxBufferSize = new_size;
     return _rxBufferSize;
 }
+
+size_t HardwareSerial::setTxBufferSize(size_t new_size) {
+
+    if (_uart) {
+        log_e("TX Buffer can't be resized when Serial is already running.\n");
+        return 0;
+    }
+
+    if (new_size <= SOC_UART_FIFO_LEN) {
+        log_e("TX Buffer must be higher than %d.\n", SOC_UART_FIFO_LEN);  // ESP32, S2, S3 and C3 means higher than 128
+        return 0;
+    }
+
+    _txBufferSize = new_size;
+    return _txBufferSize;
+}

cores/esp32/HardwareSerial.h

@@ -132,11 +132,13 @@ public:
     void setHwFlowCtrlMode(uint8_t mode = HW_FLOWCTRL_CTS_RTS, uint8_t threshold = 64);   // 64 is half FIFO Length
 
     size_t setRxBufferSize(size_t new_size);
+    size_t setTxBufferSize(size_t new_size);
 
 protected:
     int _uart_nr;
     uart_t* _uart;
     size_t _rxBufferSize;
+    size_t _txBufferSize;
     OnReceiveCb _onReceiveCB;
     OnReceiveErrorCb _onReceiveErrorCB;
     TaskHandle_t _eventTask;

cores/esp32/esp32-hal-uart.c

@@ -130,7 +130,7 @@ void uartSetHwFlowCtrlMode(uart_t *uart, uint8_t mode, uint8_t threshold) {
 }
 
 
-uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rxPin, int8_t txPin, uint16_t queueLen, bool inverted, uint8_t rxfifo_full_thrhd)
+uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rxPin, int8_t txPin, uint16_t rx_buffer_size, uint16_t tx_buffer_size, bool inverted, uint8_t rxfifo_full_thrhd)
 {
     if(uart_nr >= SOC_UART_NUM) {
         return NULL;
@@ -163,7 +163,7 @@ uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rx
     uart_config.source_clk = UART_SCLK_APB;
 
 
-    ESP_ERROR_CHECK(uart_driver_install(uart_nr, 2*queueLen, 0, 20, &(uart->uart_event_queue), 0));
+    ESP_ERROR_CHECK(uart_driver_install(uart_nr, rx_buffer_size, tx_buffer_size, 20, &(uart->uart_event_queue), 0));
     ESP_ERROR_CHECK(uart_param_config(uart_nr, &uart_config));
     ESP_ERROR_CHECK(uart_set_pin(uart_nr, txPin, rxPin, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE));
 

cores/esp32/esp32-hal-uart.h

@@ -61,7 +61,7 @@ extern "C" {
 struct uart_struct_t;
 typedef struct uart_struct_t uart_t;
 
-uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rxPin, int8_t txPin, uint16_t queueLen, bool inverted, uint8_t rxfifo_full_thrhd);
+uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rxPin, int8_t txPin, uint16_t rx_buffer_size, uint16_t tx_buffer_size, bool inverted, uint8_t rxfifo_full_thrhd);
 void uartEnd(uart_t* uart);
 
 // This is used to retrieve the Event Queue pointer from a UART IDF Driver in order to allow user to deal with its events