Add I2C to StandardFirmata

Author: pjs

Firmata/examples/StandardFirmata/StandardFirmata.pde

@@ -11,6 +11,9 @@
 
 /*
   Copyright (C) 2006-2008 Hans-Christoph Steiner.  All rights reserved.
+  Copyright (C) 2010-2011 Paul Stoffregen.  All rights reserved.
+  Copyright (C) 2009 Shigeru Kobayashi.  All rights reserved.
+  Copyright (C) 2009-2011 Jeff Hoefs.  All rights reserved.
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
@@ -27,8 +30,22 @@
  */
 
 #include <Servo.h>
+#include <Wire.h>
 #include <Firmata.h>
 
+// move the following defines to Firmata.h?
+#define I2C_WRITE B00000000
+#define I2C_READ B00001000
+#define I2C_READ_CONTINUOUSLY B00010000
+#define I2C_STOP_READING B00011000
+#define I2C_READ_WRITE_MODE_MASK B00011000
+#define I2C_10BIT_ADDRESS_MODE_MASK B00100000
+
+#define MAX_QUERIES 8
+#define MINIMUM_SAMPLING_INTERVAL 10
+
+#define REGISTER_NOT_SPECIFIED -1
+
 /*==============================================================================
  * GLOBAL VARIABLES
  *============================================================================*/
@@ -50,12 +67,70 @@ unsigned long currentMillis;        // store the current value from millis()
 unsigned long previousMillis;       // for comparison with currentMillis
 int samplingInterval = 19;          // how often to run the main loop (in ms)
 
-Servo servos[MAX_SERVOS];
+/* i2c data */
+struct i2c_device_info {
+  byte addr;
+  byte reg;
+  byte bytes;
+};
 
+/* for i2c read continuous more */
+i2c_device_info query[MAX_QUERIES];
+
+byte i2cRxData[32];
+boolean readingContinuously = false;
+boolean isI2CEnabled = false;
+byte queryIndex = 0;
+unsigned int i2cReadDelayTime = 0;  // default delay time between i2c read request and Wire.requestFrom()
+
+Servo servos[MAX_SERVOS];
 /*==============================================================================
  * FUNCTIONS
  *============================================================================*/
 
+void readAndReportData(byte address, int theRegister, byte numBytes) {
+  // allow I2C requests that don't require a register read
+  // for example, some devices using an interrupt pin to signify new data available
+  // do not always require the register read so upon interrupt you call Wire.requestFrom()  
+  if (theRegister != REGISTER_NOT_SPECIFIED) {
+    Wire.beginTransmission(address);
+    #if ARDUINO >= 100
+    Wire.write((byte)theRegister);
+    #else
+    Wire.send((byte)theRegister);
+    #endif
+    Wire.endTransmission();
+    delayMicroseconds(i2cReadDelayTime);  // delay is necessary for some devices such as WiiNunchuck
+  } else {
+    theRegister = 0;  // fill the register with a dummy value
+  }
+
+  Wire.requestFrom(address, numBytes);  // all bytes are returned in requestFrom
+
+  // check to be sure correct number of bytes were returned by slave
+  if(numBytes == Wire.available()) {
+    i2cRxData[0] = address;
+    i2cRxData[1] = theRegister;
+    for (int i = 0; i < numBytes; i++) {
+      #if ARDUINO >= 100
+      i2cRxData[2 + i] = Wire.read();
+      #else
+      i2cRxData[2 + i] = Wire.receive();
+      #endif
+    }
+  }
+  else {
+    if(numBytes > Wire.available()) {
+      Firmata.sendString("I2C Read Error: Too many bytes received");
+    } else {
+      Firmata.sendString("I2C Read Error: Too few bytes received"); 
+    }
+  }
+
+  // send slave address, register and received bytes
+  Firmata.sendSysex(SYSEX_I2C_REPLY, numBytes + 2, i2cRxData);
+}
+
 void outputPort(byte portNumber, byte portValue, byte forceSend)
 {
   // pins not configured as INPUT are cleared to zeros
@@ -99,6 +174,13 @@ void checkDigitalInputs(void)
  */
 void setPinModeCallback(byte pin, int mode)
 {
+  if (pinConfig[pin] == I2C && mode != I2C) {
+    isI2CEnabled = false;
+    // uncomment the following once end() method is added to Wire library
+    // Wire.end();
+    Firmata.sendString("Once I2C is enabled, the I2C pins cannot be changed to another mode");
+    return;  
+  }
   if (IS_PIN_SERVO(pin) && mode != SERVO && servos[PIN_TO_SERVO(pin)].attached()) {
     servos[PIN_TO_SERVO(pin)].detach();
   }
@@ -155,8 +237,11 @@ void setPinModeCallback(byte pin, int mode)
     }
     break;
   case I2C:
-    pinConfig[pin] = mode;
-    Firmata.sendString("I2C mode not yet supported");
+    if (IS_PIN_I2C(pin)) {
+      pinConfig[pin] = I2C;
+      // TODO: if not enabled call enableI2CPins()?
+      // or does user have to call I2C config again in order to reenable I2C?
+    }
     break;
   default:
     Firmata.sendString("Unknown pin mode"); // TODO: put error msgs in EEPROM
@@ -243,7 +328,87 @@ void reportDigitalCallback(byte port, int value)
 
 void sysexCallback(byte command, byte argc, byte *argv)
 {
+  byte mode;
+  byte slaveAddress;
+  byte slaveRegister;
+  byte data;
+  unsigned int delayTime; 
+  
   switch(command) {
+  case I2C_REQUEST:
+    mode = argv[1] & I2C_READ_WRITE_MODE_MASK;
+    if (argv[1] & I2C_10BIT_ADDRESS_MODE_MASK) {
+      Firmata.sendString("10-bit addressing mode is not yet supported");
+      return;
+    }
+    else {
+      slaveAddress = argv[0];
+    }
+
+    switch(mode) {
+    case I2C_WRITE:
+      Wire.beginTransmission(slaveAddress);
+      for (byte i = 2; i < argc; i += 2) {
+        data = argv[i] + (argv[i + 1] << 7);
+        #if ARDUINO >= 100
+        Wire.write(data);
+        #else
+        Wire.send(data);
+        #endif
+      }
+      Wire.endTransmission();
+      delayMicroseconds(70);
+      break;
+    case I2C_READ:
+      if (argc == 6) {
+        // a slave register is specified
+        slaveRegister = argv[2] + (argv[3] << 7);
+        data = argv[4] + (argv[5] << 7);  // bytes to read
+        readAndReportData(slaveAddress, (int)slaveRegister, data);
+      }
+      else {
+        // a slave register is NOT specified
+        data = argv[2] + (argv[3] << 7);  // bytes to read
+        readAndReportData(slaveAddress, (int)REGISTER_NOT_SPECIFIED, data);
+      }
+      break;
+    case I2C_READ_CONTINUOUSLY:
+      if ((queryIndex + 1) >= MAX_QUERIES) {
+        // too many queries, just ignore
+        Firmata.sendString("too many queries");
+        break;
+      }
+      query[queryIndex].addr = slaveAddress;
+      query[queryIndex].reg = argv[2] + (argv[3] << 7);
+      query[queryIndex].bytes = argv[4] + (argv[5] << 7);
+      readingContinuously = true;
+      queryIndex++;
+      break;
+    case I2C_STOP_READING:
+      readingContinuously = false;
+      queryIndex = 0;
+      break;
+    default:
+      break;
+    }
+    break;
+  case I2C_CONFIG:
+    delayTime = (argv[4] + (argv[5] << 7));                        // MSB
+    delayTime = (delayTime << 8) + (argv[2] + (argv[3] << 7));     // add LSB
+
+    if(delayTime > 0) {
+      i2cReadDelayTime = delayTime;
+    }
+
+    if(argc > 6) {
+      // If you extend I2C_Config, handle your data here
+    }
+
+    if (!isI2CEnabled) {
+      enableI2CPins();
+    }
+    
+    break;
   case SERVO_CONFIG:
     if(argc > 4) {
       // these vars are here for clarity, they'll optimized away by the compiler
@@ -263,6 +428,9 @@ void sysexCallback(byte command, byte argc, byte *argv)
   case SAMPLING_INTERVAL:
     if (argc > 1)
       samplingInterval = argv[0] + (argv[1] << 7);
+      if (samplingInterval < MINIMUM_SAMPLING_INTERVAL) {
+        samplingInterval = MINIMUM_SAMPLING_INTERVAL;
+      }      
     else
       Firmata.sendString("Not enough data");
     break;
@@ -296,6 +464,10 @@ void sysexCallback(byte command, byte argc, byte *argv)
         Serial.write(SERVO);
         Serial.write(14);
       }
+      if (IS_PIN_I2C(pin)) {
+        Serial.write(I2C);
+        Serial.write(1);  // to do: determine appropriate value 
+      }
       Serial.write(127);
     }
     Serial.write(END_SYSEX);
@@ -326,6 +498,31 @@ void sysexCallback(byte command, byte argc, byte *argv)
   }
 }
 
+void enableI2CPins()
+{
+  byte i;
+  // is there a faster way to do this? would probaby require importing 
+  // Arduino.h to get SCL and SDA pins
+  for (i=0; i < TOTAL_PINS; i++) {
+    if(IS_PIN_I2C(i)) {
+      // mark pins as i2c so they are ignore in non i2c data requests
+      setPinModeCallback(i, I2C);
+    } 
+  }
+   
+  isI2CEnabled = true; 
+  
+  // is there enough time before the first I2C request to call this here?
+  Wire.begin();
+}
+
+void systemResetCallback()
+{
+  // clear i2c read continuous data
+  readingContinuously = false;
+  queryIndex = 0;
+}
+
 
 /*==============================================================================
  * SETUP()
@@ -342,6 +539,7 @@ void setup()
   Firmata.attach(REPORT_DIGITAL, reportDigitalCallback);
   Firmata.attach(SET_PIN_MODE, setPinModeCallback);
   Firmata.attach(START_SYSEX, sysexCallback);
+  Firmata.attach(SYSTEM_RESET, systemResetCallback);
 
   // TODO: load state from EEPROM here
 
@@ -365,7 +563,7 @@ void setup()
   analogInputsToReport = 0;
 
   Firmata.begin(57600);
-
+  
   /* send digital inputs to set the initial state on the host computer,
    * since once in the loop(), this firmware will only send on change */
   for (i=0; i < TOTAL_PORTS; i++) {
@@ -405,5 +603,11 @@ void loop()
         }
       }
     }
+    // report i2c data if read continuous mode is enabled
+    if (readingContinuously) {
+      for (byte i = 0; i < queryIndex; i++) {
+        readAndReportData(query[i].addr, query[i].reg, query[i].bytes);
+      }
+    }
   }
 }