Changes UART ISR to only trigger on RX FIFO Full and timeout (#6930)

* Changes UART ISR to only trigger on RX FIFO Full and timeout

* changes initial RX timeout

* Eliminates extra testing for _uart != NULL

* reconfiguration with "uartSetFastReading()"

* Adds new function "uartSetFastReading()"

* changed default onReceive() behaviour

* forces User callback in case of error

* Error Code Order

Set NO_ERROR as first error code, same as ESP_OK = 0

cores/esp32/HardwareSerial.cpp

@@ -140,7 +140,7 @@ _txBufferSize(0),
 _onReceiveCB(NULL), 
 _onReceiveErrorCB(NULL),
 _onReceiveTimeout(true),
-_rxTimeout(10),
+_rxTimeout(2),
 _eventTask(NULL)
 #if !CONFIG_DISABLE_HAL_LOCKS
     ,_lock(NULL)
@@ -212,6 +212,18 @@ void HardwareSerial::onReceive(OnReceiveCb function, bool onlyOnTimeout)
     HSERIAL_MUTEX_UNLOCK();
 }
 
+// This function allow the user to define how many bytes will trigger an Interrupt that will copy RX FIFO to the internal RX Ringbuffer
+// ISR will also move data from FIFO to RX Ringbuffer after a RX Timeout defined in HardwareSerial::setRxTimeout(uint8_t symbols_timeout)
+// A low value of FIFO Full bytes will consume more CPU time within the ISR
+// A high value of FIFO Full bytes will make the application wait longer to have byte available for the Stkech in a streaming scenario
+// Both RX FIFO Full and RX Timeout may affect when onReceive() will be called
+void HardwareSerial::setRxFIFOFull(uint8_t fifoBytes)
+{
+    HSERIAL_MUTEX_LOCK();
+    uartSetRxFIFOFull(_uart, fifoBytes); // Set new timeout
+    HSERIAL_MUTEX_UNLOCK();
+}
+
 // timout is calculates in time to receive UART symbols at the UART baudrate.
 // the estimation is about 11 bits per symbol (SERIAL_8N1)
 void HardwareSerial::setRxTimeout(uint8_t symbols_timeout)
@@ -223,7 +235,7 @@ void HardwareSerial::setRxTimeout(uint8_t symbols_timeout)
     _rxTimeout = symbols_timeout;   
     if (!symbols_timeout) _onReceiveTimeout = false;  // only when RX timeout is disabled, we also must disable this flag 
 
-    if(_uart != NULL) uart_set_rx_timeout(_uart_nr, _rxTimeout); // Set new timeout
+    uartSetRxTimeout(_uart, _rxTimeout); // Set new timeout
     
     HSERIAL_MUTEX_UNLOCK();
 }
@@ -250,6 +262,7 @@ void HardwareSerial::_uartEventTask(void *args)
         for(;;) {
             //Waiting for UART event.
             if(xQueueReceive(uartEventQueue, (void * )&event, (portTickType)portMAX_DELAY)) {
+                hardwareSerial_error_t currentErr = UART_NO_ERROR;
                 switch(event.type) {
                     case UART_DATA:
                         if(uart->_onReceiveCB && uart->available() > 0 && 
@@ -258,28 +271,32 @@ void HardwareSerial::_uartEventTask(void *args)
                         break;
                     case UART_FIFO_OVF:
                         log_w("UART%d FIFO Overflow. Consider adding Hardware Flow Control to your Application.", uart->_uart_nr);
-                        if(uart->_onReceiveErrorCB) uart->_onReceiveErrorCB(UART_FIFO_OVF_ERROR);
+                        currentErr = UART_FIFO_OVF_ERROR;
                         break;
                     case UART_BUFFER_FULL:
                         log_w("UART%d Buffer Full. Consider increasing your buffer size of your Application.", uart->_uart_nr);
-                        if(uart->_onReceiveErrorCB) uart->_onReceiveErrorCB(UART_BUFFER_FULL_ERROR);
+                        currentErr = UART_BUFFER_FULL_ERROR;
                         break;
                     case UART_BREAK:
                         log_w("UART%d RX break.", uart->_uart_nr);
-                        if(uart->_onReceiveErrorCB) uart->_onReceiveErrorCB(UART_BREAK_ERROR);
+                        currentErr = UART_BREAK_ERROR;
                         break;
                     case UART_PARITY_ERR:
                         log_w("UART%d parity error.", uart->_uart_nr);
-                        if(uart->_onReceiveErrorCB) uart->_onReceiveErrorCB(UART_PARITY_ERROR);
+                        currentErr = UART_PARITY_ERROR;
                         break;
                     case UART_FRAME_ERR:
                         log_w("UART%d frame error.", uart->_uart_nr);
-                        if(uart->_onReceiveErrorCB) uart->_onReceiveErrorCB(UART_FRAME_ERROR);
+                        currentErr = UART_FRAME_ERROR;
                         break;
                     default:
                         log_w("UART%d unknown event type %d.", uart->_uart_nr, event.type);
                         break;
                 }
+                if (currentErr != UART_NO_ERROR) {
+                    if(uart->_onReceiveErrorCB) uart->_onReceiveErrorCB(currentErr);
+                    if(uart->_onReceiveCB && uart->available() > 0) uart->_onReceiveCB();   // forces User Callback too
+                }
             }
         }
     }
@@ -366,9 +383,7 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
     }
 
     // Set UART RX timeout
-    if (_uart != NULL) {
+    uartSetRxTimeout(_uart, _rxTimeout);
-        uart_set_rx_timeout(_uart_nr, _rxTimeout);
-    }
 
     HSERIAL_MUTEX_UNLOCK();
 }

cores/esp32/HardwareSerial.h

@@ -57,6 +57,7 @@
 #include "freertos/semphr.h"
 
 typedef enum {
+    UART_NO_ERROR,
     UART_BREAK_ERROR,
     UART_BUFFER_FULL_ERROR,
     UART_FIFO_OVF_ERROR,
@@ -81,6 +82,12 @@ public:
     //                       For a baudrate of 9600, SERIAL_8N1 (10 bit symbol) and symbols_timeout = 3, the timeout would be 3 / (9600 / 10) = 3.125 ms
     void setRxTimeout(uint8_t symbols_timeout);
 
+    // setRxFIFOFull(uint8_t fifoBytes) will set the number of bytes that will trigger UART_INTR_RXFIFO_FULL interrupt and fill up RxRingBuffer
+    // This affects some functions such as Serial::available() and Serial.read() because, in a UART flow of receiving data, Serial internal 
+    // RxRingBuffer will be filled only after these number of bytes arrive or a RX Timeout happens.
+    // This parameter can be set to 1 in order to receive byte by byte, but it will also consume more CPU time as the ISR will be activates often.
+    void setRxFIFOFull(uint8_t fifoBytes);
+
     // onReceive will setup a callback that will be called whenever an UART interruption occurs (UART_INTR_RXFIFO_FULL or UART_INTR_RXFIFO_TOUT)
     // UART_INTR_RXFIFO_FULL interrupt triggers at UART_FULL_THRESH_DEFAULT bytes received (defined as 120 bytes by default in IDF)
     // UART_INTR_RXFIFO_TOUT interrupt triggers at UART_TOUT_THRESH_DEFAULT symbols passed without any reception (defined as 10 symbos by default in IDF)
@@ -91,7 +98,7 @@ public:
     //         false -- The callback will be called when FIFO reaches 120 bytes and also on RX Timeout.
     //                  The stream of incommig bytes will be "split" into blocks of 120 bytes on each callback.
     //                  This option avoid any sort of Rx Overflow, but leaves the UART packet reassembling work to the Application.
-    void onReceive(OnReceiveCb function, bool onlyOnTimeout = true);
+    void onReceive(OnReceiveCb function, bool onlyOnTimeout = false);
 
     // onReceive will be called on error events (see hardwareSerial_error_t)
     void onReceiveError(OnReceiveErrorCb function);

cores/esp32/esp32-hal-uart.c

@@ -162,7 +162,6 @@ uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rx
     uart_config.rx_flow_ctrl_thresh = rxfifo_full_thrhd;
     uart_config.source_clk = UART_SCLK_APB;
 
-
     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));
@@ -179,6 +178,49 @@ uart_t* uartBegin(uint8_t uart_nr, uint32_t baudrate, uint32_t config, int8_t rx
     return uart;
 }
 
+// This code is under testing - for now just keep it here
+void uartSetFastReading(uart_t* uart)
+{
+    if(uart == NULL) {
+        return;
+    }
+
+    UART_MUTEX_LOCK();
+    // override default RX IDF Driver Interrupt - no BREAK, PARITY or OVERFLOW
+    uart_intr_config_t uart_intr = {
+        .intr_enable_mask = UART_INTR_RXFIFO_FULL | UART_INTR_RXFIFO_TOUT,   // only these IRQs - no BREAK, PARITY or OVERFLOW
+        .rx_timeout_thresh = 1,
+        .txfifo_empty_intr_thresh = 10,
+        .rxfifo_full_thresh = 2,
+    };
+
+    ESP_ERROR_CHECK(uart_intr_config(uart->num, &uart_intr));
+    UART_MUTEX_UNLOCK();
+}
+
+
+void uartSetRxTimeout(uart_t* uart, uint8_t numSymbTimeout)
+{
+    if(uart == NULL) {
+        return;
+    }
+
+    UART_MUTEX_LOCK();
+    uart_set_rx_timeout(uart->num, numSymbTimeout);
+    UART_MUTEX_UNLOCK();
+}
+
+void uartSetRxFIFOFull(uart_t* uart, uint8_t numBytesFIFOFull)
+{
+    if(uart == NULL) {
+        return;
+    }
+
+    UART_MUTEX_LOCK();
+    uart_set_rx_full_threshold(uart->num, numBytesFIFOFull);
+    UART_MUTEX_UNLOCK();
+}
+
 void uartEnd(uart_t* uart)
 {
     if(uart == NULL) {

cores/esp32/esp32-hal-uart.h

@@ -82,6 +82,9 @@ void uartSetBaudRate(uart_t* uart, uint32_t baud_rate);
 uint32_t uartGetBaudRate(uart_t* uart);
 
 void uartSetRxInvert(uart_t* uart, bool invert);
+void uartSetRxTimeout(uart_t* uart, uint8_t numSymbTimeout);
+void uartSetRxFIFOFull(uart_t* uart, uint8_t numBytesFIFOFull);
+void uartSetFastReading(uart_t* uart);
 
 void uartSetDebug(uart_t* uart);
 int uartGetDebug();