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initial implementation of analog config protocol #143

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initial implementation of analog config protocol #143

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946e622
initial implementation of analog config protocol
soundanalogous Aug 1, 2014
3f09c8f
removed unnecessary ifdefs
soundanalogous Aug 1, 2014
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1 change: 1 addition & 0 deletions Firmata.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@
#define I2C_REQUEST 0x76 // send an I2C read/write request
#define I2C_REPLY 0x77 // a reply to an I2C read request
#define I2C_CONFIG 0x78 // config I2C settings such as delay times and power pins
#define ANALOG_CONFIG 0x7C // configure analog read and write resolution and reference voltage
#define EXTENDED_ANALOG 0x6F // analog write (PWM, Servo, etc) to any pin
#define PIN_STATE_QUERY 0x6D // ask for a pin's current mode and value
#define PIN_STATE_RESPONSE 0x6E // reply with pin's current mode and value
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80 changes: 78 additions & 2 deletions examples/StandardFirmata/StandardFirmata.ino
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,10 @@ boolean isI2CEnabled = false;
signed char queryIndex = -1;
unsigned int i2cReadDelayTime = 0; // default delay time between i2c read request and Wire.requestFrom()

byte analogReadRes = 10; // default - better to define in Boards.h?
byte analogWriteRes = 8; // default - better to define in Boards.h?
byte analogReferenceVoltage = DEFAULT; // defined in Arduio core for AVRs only

Servo servos[MAX_SERVOS];
/*==============================================================================
* FUNCTIONS
Expand Down Expand Up @@ -448,6 +452,78 @@ void sysexCallback(byte command, byte argc, byte *argv)
//Firmata.sendString("Not enough data");
}
break;
case ANALOG_CONFIG:
if (argc > 1) {
switch (argv[0]) {
case 0: // set analog reference voltage
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SAM-based variants would need to skip this entire case.

// currently analogReference is only definved for AVR boards
// see: http://arduino.cc/en/Reference/AnalogReference
switch (argv[1]) {
// note that the following 5 case values do not equal the actual
// value of the corresponding constant. The constant value may change
// by board type (Mega vs Uno, etc)
case 0: // DEFAULT (5v on 5v boards, 3.3v on 3.3v boards)
analogReference(DEFAULT);
analogReferenceVoltage = DEFAULT;
break;
#ifdef INTERNAL
case 1: // INTERNAL
analogReference(INTERNAL);
analogReferenceVoltage = INTERNAL;
break;
#endif
#ifdef INTERNAL1V1
case 2: // INTERNAL1V1
analogReference(INTERNAL1V1);
analogReferenceVoltage = INTERNAL1V1;
break;
#endif
#ifdef INTERNAL2V56
case 3: // INTERNAL_2V56
analogReference(INTERNAL2V56);
analogReferenceVoltage = INTERNAL2V56;
break;
#endif
case 4: // EXTERNAL (0 to 5V applied to AREF pin)
analogReference(EXTERNAL);
analogReferenceVoltage = EXTERNAL;
break;
}

break;
case 1: // query analog reference voltage
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I don't like that this has to be separate from the configuration query but I'm not sure how else to do it since adding a second value to analog read and analog write (pwm) for the respective values in the configuration query response would likely break existing Firmata client implementations (since currently the response is pinType: value for each pin type).

Firmata.write(START_SYSEX);
Firmata.write(ANALOG_CONFIG);
Firmata.write(1); // analog reference response
Firmata.write(analogReferenceVoltage);
Firmata.write(END_SYSEX);
break;
#if ARDUINO >= 150
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This would really need to determine not only if the version is 1.5 or higher, but whether or not the board is a SAM or AVR architecture. AVR boards don't include the analogReadResolution and analogWriteResolution methods.

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After looking into this further I've determined that I could use the existing constants ARDUINO_ARCH_AVR and ARDUINO_ARCH_SAM. However that would likely leave out compatible 3rd party boards such as Teensy.

// to do: need to exclude AVRs
// only available for SAM core boards
// not available for all boards, but will safely default to proper
// resolution for unsupported boards
case 2: // set analog read resolution (defaults to 10 bits for AVR boards)
if (argv[1] > 0 && argv[1] < 33) {
// see: http://arduino.cc/en/Reference/analogReadResolution
// values above the boards capability are truncated
// values below the min supported resolution will be zero padded
analogReadResolution(argv[1]);
analogReadRes = argv[1];
}
break;
case 3: // set analog write (pwm) resolution (defaults to 8 bits for AVR boards)
if (argv[1] > 0 && argv[1] < 33) {
// see: http://arduino.cc/en/Reference/analogWriteResolution
// values above the boards capability are truncated
// values below the min supported resolution will be zero padded
analogWriteResolution(argv[1]);
analogWriteRes = argv[1];
}
break;
#endif
}
}
case EXTENDED_ANALOG:
if (argc > 1) {
int val = argv[1];
Expand All @@ -468,11 +544,11 @@ void sysexCallback(byte command, byte argc, byte *argv)
}
if (IS_PIN_ANALOG(pin)) {
Firmata.write(ANALOG);
Firmata.write(10);
Firmata.write(analogReadRes);
}
if (IS_PIN_PWM(pin)) {
Firmata.write(PWM);
Firmata.write(8);
Firmata.write(analogWriteRes);
}
if (IS_PIN_SERVO(pin)) {
Firmata.write(SERVO);
Expand Down