Add esp32 support with CRC handling

src/SDI12.cpp

@@ -547,32 +547,130 @@ void SDI12::sendResponse(FlashString resp) {
   setState(SDI12_LISTENING);  // return to listening state
 }
 
+#ifdef ENVIRODIY_SDI12_USE_CRC
+
+#define POLY 0xa001
+String SDI12::addCRCResponse(String &resp) {
+  char  crcStr[3] = {0};
+  uint16_t crc    = 0;
+
+  for(int i = 0; i < resp.length(); i++) {
+    crc ^= (uint16_t)resp[i];     //Set the CRC equal to the exclusive OR of the character and itself
+    for (int j = 0; j <  8; j++){ //count = 1 to 8
+      if (crc & 0x0001){          //if the least significant bit of the CRC is one
+        crc >>= 1;                //right shift the CRC one bit
+        crc ^= POLY;              //set CRC equal to the exclusive OR of POLY and itself
+      }
+      else {
+        crc >>=  1;               //right shift the CRC one bit
+      }
+    }
+  }
+  crcStr[0] = (char)( 0x0040 |  (crc >> 12));
+  crcStr[1] = (char)( 0x0040 | ((crc >> 6) & 0x003F));
+  crcStr[2] = (char)( 0x0040 |  (crc & 0x003F));
+  return (resp  + String(crcStr[0]) + String(crcStr[1]) + String(crcStr[2]));
+}
 
-/* ================ Interrupt Service Routine =======================================*/
 
-// Passes off responsibility for the interrupt to the active object.
-// On espressif boards (ESP8266 and ESP32), the ISR must be stored in IRAM
-#if defined(ESP32) || defined(ESP8266)
-void ICACHE_RAM_ATTR SDI12::handleInterrupt() {
-  if (_activeObject) _activeObject->receiveISR();
+char * SDI12::addCRCResponse(char *resp) {
+  char crcStr[3] = {0};
+  uint16_t crc    = 0;
+
+  for(int i = 0; i < strlen(resp); i++) {
+    crc ^= (uint16_t)resp[i];     //Set the CRC equal to the exclusive OR of the character and itself
+    for (int j = 0; j <  8; j++){ //count = 1 to 8
+      if (crc & 0x0001){          //if the least significant bit of the CRC is one
+        crc >>= 1;                //right shift the CRC one bit
+        crc ^= POLY;              //set CRC equal to the exclusive OR of POLY and itself
+      }
+      else {
+        crc >>=  1;             //right shift the CRC one bit
+      }
+    }
+  }
+
+  crcStr[1] = (char)( 0x0040 | ((crc >> 6) & 0x003F));
+  crcStr[2] = (char)( 0x0040 |  (crc & 0x003F));
+  return (strncat(resp, crcStr,3));
+}
+
+String SDI12::addCRCResponse(FlashString resp) {
+  char  crcStr[3] = {0};
+  char  respBuffer[SDI12_BUFFER_SIZE - 5]; // don't need space for the CRC or CR/LF
+  uint16_t crc    = 0;
+  int i = 0;
+  char responsechar ;
+
+
+  for(i = 0; i < strlen_P((PGM_P)resp); i++) {
+    responsechar = (char)pgm_read_byte((const char *)resp + i);
+    crc ^= (uint16_t)responsechar;     //Set the CRC equal to the exclusive OR of the character and itself
+    for (int j = 0; j <  8; j++){      //count = 1 to 8
+       if (crc & 0x0001){              //if the least significant bit of the CRC is one
+          crc >>= 1;                   //right shift the CRC one bit
+          crc ^= POLY;                 //set CRC equal to the exclusive OR of POLY and itself
+       }
+       else {
+          crc >>=  1;                  //right shift the CRC one bit
+       }
+    }
+    respBuffer[i] = responsechar;
+  }
+  respBuffer[++i] = '\0';
+  String outResp = respBuffer;
+  crcStr[0] = (char)( 0x0040 |  (crc >> 12));
+  crcStr[1] = (char)( 0x0040 | ((crc >> 6) & 0x003F));
+  crcStr[2] = (char)( 0x0040 |  (crc & 0x003F));
+  return (outResp  + String(crcStr[0]) + String(crcStr[1]) + String(crcStr[2]));
+}
+
+String SDI12::calculateCRC(String &resp){
+   char  crcStr[3] = {0};
+   uint16_t crc    = 0;
+
+   for(int i = 0; i < resp.length(); i++) {
+      crc ^= (uint16_t)resp[i];     //Set the CRC equal to the exclusive OR of the character and itself
+      for (int j = 0; j <  8; j++){ //count = 1 to 8
+         if (crc & 0x0001){         //if the least significant bit of the CRC is one
+            crc >>= 1;              //right shift the CRC one bit
+            crc ^= POLY;            //set CRC equal to the exclusive OR of POLY and itself
+         }
+         else {
+            crc >>=  1;             //right shift the CRC one bit
+         }
+      }
+   }
+   crcStr[0] = (char)( 0x0040 |  (crc >> 12));
+   crcStr[1] = (char)( 0x0040 | ((crc >> 6) & 0x003F));
+   crcStr[2] = (char)( 0x0040 |  (crc & 0x003F));
+   return (String(crcStr[0]) + String(crcStr[1]) + String(crcStr[2]));
 }
-#else
-void SDI12::handleInterrupt() {
+
+#endif //ENVIRODIY_SDI12_USE_CRC
+
+
+
+/* ================ Interrupt Service Routine =======================================*/
+
+// 7.1 - Passes off responsibility for the interrupt to the active object.
+void ESPFAMILY_USE_INSTRUCTION_RAM SDI12::handleInterrupt(){
   if (_activeObject) _activeObject->receiveISR();
 }
-#endif
 
-// Creates a blank slate of bits for an incoming character
-void SDI12::startChar() {
-  rxState = 0x00;  // 0b00000000, got a start bit
+// 7.2 - Creates a blank slate of bits for an incoming character
+void ESPFAMILY_USE_INSTRUCTION_RAM SDI12::startChar()
+{
+  rxState = 0;           // got a start bit
   rxMask  = 0x01;  // 0b00000001, bit mask, lsb first
   rxValue = 0x00;  // 0b00000000, RX character to be, a blank slate
 }  // startChar
 
-// The actual interrupt service routine
-void SDI12::receiveISR() {
-  // time of this data transition (plus ISR latency)
-  sdi12timer_t thisBitTCNT = READTIME;
+// 7.3 - The actual interrupt service routine
+void ESPFAMILY_USE_INSTRUCTION_RAM SDI12::receiveISR()
+{
+
+  sdi12timer_t thisBitTCNT = READTIME;       // time of this data transition (plus ISR latency)
 
   uint8_t pinLevel = digitalRead(_dataPin);  // current RX data level
 

src/SDI12.h

@@ -126,6 +126,7 @@
 #define SRC_SDI12_H_
 
 //  Import Required Libraries
+
 #include <inttypes.h>      // integer types library
 #include <Arduino.h>       // Arduino core library
 #include <Stream.h>        // Arduino Stream library
@@ -180,6 +181,7 @@ enum LookaheadMode {
   /** Only tabs, spaces, line feeds & carriage returns are skipped.*/
   SKIP_WHITESPACE
 };
+
 /**
  * @brief The function or macro used to read the clock timer value.
  *
@@ -190,6 +192,7 @@ enum LookaheadMode {
  * use the micros function and must use the faster assembly macros to read the
  * processor timer directly.
  */
+
 #define READTIME sdi12timer.SDI12TimerRead()
 #else
 /**
@@ -910,6 +913,13 @@ class SDI12 : public Stream {
   /// @copydoc SDI12::sendCommand(String&, int8_t)
   void sendCommand(FlashString cmd, int8_t extraWakeTime = SDI12_WAKE_DELAY);
 
+ #ifdef ENVIRODIY_SDI12_USE_CRC
+  String addCRCResponse(String &resp);     // Add CRC to the  resp  string (for slave use)
+  char * addCRCResponse( char *resp);      // Add CRC to the  resp  string (for slave use)
+  String addCRCResponse(FlashString resp); // Add CRC to the  resp  string (for slave use)
+  String calculateCRC(String &resp);       // Calculate the CRC for a response
+ #endif
+
   /**
    * @brief Send a response out on the data line (for slave use)
    *
@@ -926,7 +936,6 @@ class SDI12 : public Stream {
   void sendResponse(FlashString resp);
   ///@}
 
-
   /**
    * @anchor interrupt_fxns
    * @name Interrupt Service Routine
@@ -976,6 +985,7 @@ class SDI12 : public Stream {
   /** on AVR boards, uncomment to use your own PCINT ISRs */
   // #define SDI12_EXTERNAL_PCINT
   /**@}*/
+
 };
 
 #endif  // SRC_SDI12_H_

src/SDI12_boards.cpp

@@ -266,12 +266,13 @@ void SDI12Timer::resetSDI12TimerPrescale(void) {
 //
 #elif defined(ESP32) || defined(ESP8266)
 
-void         SDI12Timer::configSDI12TimerPrescale(void) {}
-void         SDI12Timer::resetSDI12TimerPrescale(void) {}
-sdi12timer_t SDI12Timer::SDI12TimerRead(void) {
-  // Its a one microsecond clock but we want 64uS ticks so divide by 64 i.e. right shift
-  // 6
-  return ((sdi12timer_t)(micros() >> 6));
+void SDI12Timer::configSDI12TimerPrescale(void) {}
+void SDI12Timer::resetSDI12TimerPrescale(void) {}
+
+sdi12timer_t ESPFAMILY_USE_INSTRUCTION_RAM SDI12Timer::SDI12TimerRead(void)
+{
+   // Its a one microsecond clock but we want 64uS ticks so divide by 64 i.e. right shift 6
+   return ((sdi12timer_t)(micros() >> 6));
 }
 // Unknown board
 #else

src/SDI12_boards.h

@@ -19,9 +19,13 @@ sensors. This library provides a general software solution, without requiring
 #include <Arduino.h>
 
 #if defined(ESP32) || defined(ESP8266)
+// On espressif boards (ESP8266 and ESP32), the ISR must be stored in IRAM
+#define ESPFAMILY_USE_INSTRUCTION_RAM IRAM_ATTR
 /** The interger type (size) of the timer return value */
 typedef uint32_t sdi12timer_t;
+
 #else
+#define ESPFAMILY_USE_INSTRUCTION_RAM
 /** The interger type (size) of the timer return value */
 typedef uint8_t sdi12timer_t;
 #endif