enable option to auto restart i2c transmission per issue firmata#82

Author: soundanalogous

examples/StandardFirmata/StandardFirmata.ino

@@ -33,6 +33,10 @@
 #define I2C_STOP_READING            B00011000
 #define I2C_READ_WRITE_MODE_MASK    B00011000
 #define I2C_10BIT_ADDRESS_MODE_MASK B00100000
+#define I2C_END_TX_MASK             B01000000
+#define I2C_STOP_TX                 1
+#define I2C_RESTART_TX              0
+
 #define I2C_MAX_QUERIES             8
 #define I2C_REGISTER_NOT_SPECIFIED  -1
 
@@ -66,6 +70,7 @@ struct i2c_device_info {
   byte addr;
   int reg;
   byte bytes;
+  byte stopTX;
 };
 
 /* for i2c read continuous more */
@@ -153,7 +158,7 @@ void readAndReportData(byte address, int theRegister, byte numBytes) {
   if (theRegister != I2C_REGISTER_NOT_SPECIFIED) {
     Wire.beginTransmission(address);
     wireWrite((byte)theRegister);
-    Wire.endTransmission();
+    Wire.endTransmission(stopTX); // default = true
     // do not set a value of 0
     if (i2cReadDelayTime > 0) {
       // delay is necessary for some devices such as WiiNunchuck
@@ -435,6 +440,7 @@ void reportDigitalCallback(byte port, int value)
 void sysexCallback(byte command, byte argc, byte *argv)
 {
   byte mode;
+  byte stopTX;
   byte slaveAddress;
   byte data;
   int slaveRegister;
@@ -451,6 +457,14 @@ void sysexCallback(byte command, byte argc, byte *argv)
         slaveAddress = argv[0];
       }
 
+      // need to invert the logic here since 0 will be default for client
+      // libraries that have not updated to add support for restart tx
+      if (argv[1] & I2C_END_TX_MASK) {
+        stopTX = I2C_RESTART_TX;
+      }
+      else {
+        stopTX = I2C_STOP_TX; // default
+      }
       switch (mode) {
         case I2C_WRITE:
           Wire.beginTransmission(slaveAddress);
@@ -472,7 +486,7 @@ void sysexCallback(byte command, byte argc, byte *argv)
             slaveRegister = I2C_REGISTER_NOT_SPECIFIED;
             data = argv[2] + (argv[3] << 7);  // bytes to read
           }
-          readAndReportData(slaveAddress, (int)slaveRegister, data);
+          readAndReportData(slaveAddress, (int)slaveRegister, data, stopTX);
           break;
         case I2C_READ_CONTINUOUSLY:
           if ((queryIndex + 1) >= I2C_MAX_QUERIES) {
@@ -494,6 +508,7 @@ void sysexCallback(byte command, byte argc, byte *argv)
           query[queryIndex].addr = slaveAddress;
           query[queryIndex].reg = slaveRegister;
           query[queryIndex].bytes = data;
+          query[queryIndex].stopTX = stopTX;
           break;
         case I2C_STOP_READING:
           byte queryIndexToSkip;
@@ -517,6 +532,7 @@ void sysexCallback(byte command, byte argc, byte *argv)
                 query[i].addr = query[i + 1].addr;
                 query[i].reg = query[i + 1].reg;
                 query[i].bytes = query[i + 1].bytes;
+                query[i].stopTX = query[i + 1].stopTX;
               }
             }
             queryIndex--;
@@ -765,7 +781,7 @@ void loop()
     // report i2c data for all device with read continuous mode enabled
     if (queryIndex > -1) {
       for (byte i = 0; i < queryIndex + 1; i++) {
-        readAndReportData(query[i].addr, query[i].reg, query[i].bytes);
+        readAndReportData(query[i].addr, query[i].reg, query[i].bytes, query[i].stopTX);
       }
     }
   }