Add API for selecting Rx GPIO PULLUP at runtime.

Author: dok-net

library.json

@@ -1,6 +1,6 @@
 {
     "name": "EspSoftwareSerial",
-    "version": "6.13.2",
+    "version": "6.14.0",
     "description": "Implementation of the Arduino software serial for ESP8266/ESP32.",
     "keywords": [
         "serial", "io", "softwareserial"

library.properties

@@ -1,5 +1,5 @@
 name=EspSoftwareSerial
-version=6.13.2
+version=6.14.0
 author=Dirk Kaar, Peter Lerup
 maintainer=Dirk Kaar <dok@dok-net.net>
 sentence=Implementation of the Arduino software serial for ESP8266/ESP32.

src/SoftwareSerial.cpp

@@ -107,6 +107,12 @@ bool SoftwareSerial::hasRxGPIOPullUp(int8_t pin) {
 #endif
 }
 
+void SoftwareSerial::setRxGPIOPullUp() {
+    if (m_rxValid) {
+        pinMode(m_rxPin, hasRxGPIOPullUp(m_rxPin) && m_rxGPIOPullupEnabled ? INPUT_PULLUP : INPUT);
+    }
+}
+
 void SoftwareSerial::begin(uint32_t baud, SoftwareSerialConfig config,
     int8_t rxPin, int8_t txPin,
     bool invert, int bufCapacity, int isrBufCapacity) {
@@ -120,6 +126,7 @@ void SoftwareSerial::begin(uint32_t baud, SoftwareSerialConfig config,
     m_pduBits = m_dataBits + static_cast<bool>(m_parityMode) + m_stopBits;
     m_bitCycles = (ESP.getCpuFreqMHz() * 1000000UL + baud / 2) / baud;
     m_intTxEnabled = true;
+    m_rxGPIOPullupEnabled = true;
     if (isValidRxGPIOpin(m_rxPin)) {
         m_buffer.reset(new circular_queue<uint8_t>((bufCapacity > 0) ? bufCapacity : 64));
         if (m_parityMode)
@@ -131,7 +138,7 @@ void SoftwareSerial::begin(uint32_t baud, SoftwareSerialConfig config,
             isrBufCapacity : m_buffer->capacity() * (2 + m_dataBits + static_cast<bool>(m_parityMode))));
         if (m_buffer && (!m_parityMode || m_parityBuffer) && m_isrBuffer) {
             m_rxValid = true;
-            pinMode(m_rxPin, hasRxGPIOPullUp(m_rxPin) ? INPUT_PULLUP : INPUT);
+            setRxGPIOPullUp();
         }
     }
     if (isValidTxGPIOpin(m_txPin)) {
@@ -177,6 +184,11 @@ void SoftwareSerial::enableIntTx(bool on) {
     m_intTxEnabled = on;
 }
 
+void SoftwareSerial::enableRxGPIOPullup(bool on) {
+    m_rxGPIOPullupEnabled = on;
+    setRxGPIOPullUp();
+}
+
 void SoftwareSerial::enableTx(bool on) {
     if (m_txValid && m_oneWire) {
         if (on) {
@@ -185,7 +197,7 @@ void SoftwareSerial::enableTx(bool on) {
             digitalWrite(m_txPin, !m_invert);
         }
         else {
-            pinMode(m_rxPin, hasRxGPIOPullUp(m_rxPin) ? INPUT_PULLUP : INPUT);
+            setRxGPIOPullUp();
             enableRx(true);
         }
     }

src/SoftwareSerial.h

@@ -122,8 +122,10 @@ class SoftwareSerial : public Stream {
     uint32_t baudRate();
     /// Transmit control pin.
     void setTransmitEnablePin(int8_t txEnablePin);
-    /// Enable or disable interrupts during tx.
+    /// Enable (default) or disable interrupts during tx.
     void enableIntTx(bool on);
+    /// Enable (default) or disable internal rx GPIO pullup.
+    void enableRxGPIOPullup(bool on);
 
     bool overflow();
 
@@ -222,6 +224,8 @@ class SoftwareSerial : public Stream {
     bool isValidTxGPIOpin(int8_t pin);
     // result is only defined for a valid Rx GPIO pin
     bool hasRxGPIOPullUp(int8_t pin);
+    // safely set the pin mode for the Rx GPIO pin
+    void setRxGPIOPullUp();
     /* check m_rxValid that calling is safe */
     void rxBits();
     void rxBits(const uint32_t& isrCycle);
@@ -243,6 +247,7 @@ class SoftwareSerial : public Stream {
     /// PDU bits include data, parity and stop bits; the start bit is not counted.
     uint8_t m_pduBits;
     bool m_intTxEnabled;
+    bool m_rxGPIOPullupEnabled;
     SoftwareSerialParity m_parityMode;
     uint8_t m_stopBits;
     bool m_lastReadParity;