I am trying to use teensy for data acquisition, mostly reading analog inputs and controlling digital outputs. Below is my test environment:
When I try to use pyfirmata or pyfirmata2 to sample analog reads, the serial messages got periodic pauses every 1-2 seconds. It's worth noting that all the serial messages are finally sent to the computer, but it's highly delayed. It looks like the transmission of serial messages is paused for ~1.5 seconds.
See below for the ino code and python code.
python code:
The ino code is the same as examples/standardFirmata, but I hardcoded the sampling interval to be 1 ms. And the python code here simply wait for the serial message, timestamp it, and then reads it. If you plot the time stamps of serial messages, you will see clear gaps between chunks of messages, but the total number of messages is correct. So, we didn't lost serial packages, but it's just got chunked and delayed.
This issue is not present for Arduino Uno at 1 Khz, and it's for Teensy at higher sampling rates (>200 hz.)
Code:
teensy board: 3.5
arduino: 1.8.19
teensyduino: 1.56
USB type: serial
CPU speed: 120Mhz
optimize: faster
python: 3.9.7
pyfirmata: 1.1.0When I try to use pyfirmata or pyfirmata2 to sample analog reads, the serial messages got periodic pauses every 1-2 seconds. It's worth noting that all the serial messages are finally sent to the computer, but it's highly delayed. It looks like the transmission of serial messages is paused for ~1.5 seconds.
See below for the ino code and python code.
Code:
/*
Firmata is a generic protocol for communicating with microcontrollers
from software on a host computer. It is intended to work with
any host computer software package.
To download a host software package, please click on the following link
to open the list of Firmata client libraries in your default browser.
https://github.com/firmata/arduino#firmata-client-libraries
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) 2009-2016 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
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
See file LICENSE.txt for further informations on licensing terms.
Last updated August 17th, 2017
*/
#include <Servo.h>
#include <Wire.h>
#include <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 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
// the minimum interval for sampling analog input
#define MINIMUM_SAMPLING_INTERVAL 1
/*==============================================================================
* GLOBAL VARIABLES
*============================================================================*/
#ifdef FIRMATA_SERIAL_FEATURE
SerialFirmata serialFeature;
#endif
/* analog inputs */
int analogInputsToReport = 0; // bitwise array to store pin reporting
/* digital input ports */
byte reportPINs[TOTAL_PORTS]; // 1 = report this port, 0 = silence
byte previousPINs[TOTAL_PORTS]; // previous 8 bits sent
/* pins configuration */
byte portConfigInputs[TOTAL_PORTS]; // each bit: 1 = pin in INPUT, 0 = anything else
/* timer variables */
unsigned long currentMillis; // store the current value from millis()
unsigned long previousMillis; // for comparison with currentMillis
unsigned int samplingInterval = 19; // how often to run the main loop (in ms)
/* i2c data */
struct i2c_device_info {
byte addr;
int reg;
byte bytes;
byte stopTX;
};
/* for i2c read continuous more */
i2c_device_info query[I2C_MAX_QUERIES];
byte i2cRxData[64];
boolean isI2CEnabled = false;
signed char queryIndex = -1;
// default delay time between i2c read request and Wire.requestFrom()
unsigned int i2cReadDelayTime = 0;
Servo servos[MAX_SERVOS];
byte servoPinMap[TOTAL_PINS];
byte detachedServos[MAX_SERVOS];
byte detachedServoCount = 0;
byte servoCount = 0;
boolean isResetting = false;
// Forward declare a few functions to avoid compiler errors with older versions
// of the Arduino IDE.
void setPinModeCallback(byte, int);
void reportAnalogCallback(byte analogPin, int value);
void sysexCallback(byte, byte, byte*);
/* utility functions */
void wireWrite(byte data)
{
#if ARDUINO >= 100
Wire.write((byte)data);
#else
Wire.send(data);
#endif
}
byte wireRead(void)
{
#if ARDUINO >= 100
return Wire.read();
#else
return Wire.receive();
#endif
}
/*==============================================================================
* FUNCTIONS
*============================================================================*/
void attachServo(byte pin, int minPulse, int maxPulse)
{
if (servoCount < MAX_SERVOS) {
// reuse indexes of detached servos until all have been reallocated
if (detachedServoCount > 0) {
servoPinMap[pin] = detachedServos[detachedServoCount - 1];
if (detachedServoCount > 0) detachedServoCount--;
} else {
servoPinMap[pin] = servoCount;
servoCount++;
}
if (minPulse > 0 && maxPulse > 0) {
servos[servoPinMap[pin]].attach(PIN_TO_DIGITAL(pin), minPulse, maxPulse);
} else {
servos[servoPinMap[pin]].attach(PIN_TO_DIGITAL(pin));
}
} else {
Firmata.sendString("Max servos attached");
}
}
void detachServo(byte pin)
{
servos[servoPinMap[pin]].detach();
// if we're detaching the last servo, decrement the count
// otherwise store the index of the detached servo
if (servoPinMap[pin] == servoCount && servoCount > 0) {
servoCount--;
} else if (servoCount > 0) {
// keep track of detached servos because we want to reuse their indexes
// before incrementing the count of attached servos
detachedServoCount++;
detachedServos[detachedServoCount - 1] = servoPinMap[pin];
}
servoPinMap[pin] = 255;
}
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, PIN_MODE_I2C);
}
}
isI2CEnabled = true;
Wire.begin();
}
/* disable the i2c pins so they can be used for other functions */
void disableI2CPins() {
isI2CEnabled = false;
// disable read continuous mode for all devices
queryIndex = -1;
}
void readAndReportData(byte address, int theRegister, byte numBytes, byte stopTX) {
// 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 != I2C_REGISTER_NOT_SPECIFIED) {
Wire.beginTransmission(address);
wireWrite((byte)theRegister);
Wire.endTransmission(stopTX); // default = true
// do not set a value of 0
if (i2cReadDelayTime > 0) {
// delay is necessary for some devices such as WiiNunchuck
delayMicroseconds(i2cReadDelayTime);
}
} 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()) {
Firmata.sendString("I2C: Too many bytes received");
} else if (numBytes > Wire.available()) {
Firmata.sendString("I2C: Too few bytes received");
}
i2cRxData[0] = address;
i2cRxData[1] = theRegister;
for (int i = 0; i < numBytes && Wire.available(); i++) {
i2cRxData[2 + i] = wireRead();
}
// 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
portValue = portValue & portConfigInputs[portNumber];
// only send if the value is different than previously sent
if (forceSend || previousPINs[portNumber] != portValue) {
Firmata.sendDigitalPort(portNumber, portValue);
previousPINs[portNumber] = portValue;
}
}
/* -----------------------------------------------------------------------------
* check all the active digital inputs for change of state, then add any events
* to the Serial output queue using Serial.print() */
void checkDigitalInputs(void)
{
/* Using non-looping code allows constants to be given to readPort().
* The compiler will apply substantial optimizations if the inputs
* to readPort() are compile-time constants. */
if (TOTAL_PORTS > 0 && reportPINs[0]) outputPort(0, readPort(0, portConfigInputs[0]), false);
if (TOTAL_PORTS > 1 && reportPINs[1]) outputPort(1, readPort(1, portConfigInputs[1]), false);
if (TOTAL_PORTS > 2 && reportPINs[2]) outputPort(2, readPort(2, portConfigInputs[2]), false);
if (TOTAL_PORTS > 3 && reportPINs[3]) outputPort(3, readPort(3, portConfigInputs[3]), false);
if (TOTAL_PORTS > 4 && reportPINs[4]) outputPort(4, readPort(4, portConfigInputs[4]), false);
if (TOTAL_PORTS > 5 && reportPINs[5]) outputPort(5, readPort(5, portConfigInputs[5]), false);
if (TOTAL_PORTS > 6 && reportPINs[6]) outputPort(6, readPort(6, portConfigInputs[6]), false);
if (TOTAL_PORTS > 7 && reportPINs[7]) outputPort(7, readPort(7, portConfigInputs[7]), false);
if (TOTAL_PORTS > 8 && reportPINs[8]) outputPort(8, readPort(8, portConfigInputs[8]), false);
if (TOTAL_PORTS > 9 && reportPINs[9]) outputPort(9, readPort(9, portConfigInputs[9]), false);
if (TOTAL_PORTS > 10 && reportPINs[10]) outputPort(10, readPort(10, portConfigInputs[10]), false);
if (TOTAL_PORTS > 11 && reportPINs[11]) outputPort(11, readPort(11, portConfigInputs[11]), false);
if (TOTAL_PORTS > 12 && reportPINs[12]) outputPort(12, readPort(12, portConfigInputs[12]), false);
if (TOTAL_PORTS > 13 && reportPINs[13]) outputPort(13, readPort(13, portConfigInputs[13]), false);
if (TOTAL_PORTS > 14 && reportPINs[14]) outputPort(14, readPort(14, portConfigInputs[14]), false);
if (TOTAL_PORTS > 15 && reportPINs[15]) outputPort(15, readPort(15, portConfigInputs[15]), false);
}
// -----------------------------------------------------------------------------
/* sets the pin mode to the correct state and sets the relevant bits in the
* two bit-arrays that track Digital I/O and PWM status
*/
void setPinModeCallback(byte pin, int mode)
{
if (Firmata.getPinMode(pin) == PIN_MODE_IGNORE)
return;
if (Firmata.getPinMode(pin) == PIN_MODE_I2C && isI2CEnabled && mode != PIN_MODE_I2C) {
// disable i2c so pins can be used for other functions
// the following if statements should reconfigure the pins properly
disableI2CPins();
}
if (IS_PIN_DIGITAL(pin) && mode != PIN_MODE_SERVO) {
if (servoPinMap[pin] < MAX_SERVOS && servos[servoPinMap[pin]].attached()) {
detachServo(pin);
}
}
if (IS_PIN_ANALOG(pin)) {
reportAnalogCallback(PIN_TO_ANALOG(pin), mode == PIN_MODE_ANALOG ? 1 : 0); // turn on/off reporting
}
if (IS_PIN_DIGITAL(pin)) {
if (mode == INPUT || mode == PIN_MODE_PULLUP) {
portConfigInputs[pin / 8] |= (1 << (pin & 7));
} else {
portConfigInputs[pin / 8] &= ~(1 << (pin & 7));
}
}
Firmata.setPinState(pin, 0);
switch (mode) {
case PIN_MODE_ANALOG:
if (IS_PIN_ANALOG(pin)) {
if (IS_PIN_DIGITAL(pin)) {
pinMode(PIN_TO_DIGITAL(pin), INPUT); // disable output driver
#if ARDUINO <= 100
// deprecated since Arduino 1.0.1 - TODO: drop support in Firmata 2.6
digitalWrite(PIN_TO_DIGITAL(pin), LOW); // disable internal pull-ups
#endif
}
Firmata.setPinMode(pin, PIN_MODE_ANALOG);
}
break;
case INPUT:
if (IS_PIN_DIGITAL(pin)) {
pinMode(PIN_TO_DIGITAL(pin), INPUT); // disable output driver
#if ARDUINO <= 100
// deprecated since Arduino 1.0.1 - TODO: drop support in Firmata 2.6
digitalWrite(PIN_TO_DIGITAL(pin), LOW); // disable internal pull-ups
#endif
Firmata.setPinMode(pin, INPUT);
}
break;
case PIN_MODE_PULLUP:
if (IS_PIN_DIGITAL(pin)) {
pinMode(PIN_TO_DIGITAL(pin), INPUT_PULLUP);
Firmata.setPinMode(pin, PIN_MODE_PULLUP);
Firmata.setPinState(pin, 1);
}
break;
case OUTPUT:
if (IS_PIN_DIGITAL(pin)) {
if (Firmata.getPinMode(pin) == PIN_MODE_PWM) {
// Disable PWM if pin mode was previously set to PWM.
digitalWrite(PIN_TO_DIGITAL(pin), LOW);
}
pinMode(PIN_TO_DIGITAL(pin), OUTPUT);
Firmata.setPinMode(pin, OUTPUT);
}
break;
case PIN_MODE_PWM:
if (IS_PIN_PWM(pin)) {
pinMode(PIN_TO_PWM(pin), OUTPUT);
analogWrite(PIN_TO_PWM(pin), 0);
Firmata.setPinMode(pin, PIN_MODE_PWM);
}
break;
case PIN_MODE_SERVO:
if (IS_PIN_DIGITAL(pin)) {
Firmata.setPinMode(pin, PIN_MODE_SERVO);
if (servoPinMap[pin] == 255 || !servos[servoPinMap[pin]].attached()) {
// pass -1 for min and max pulse values to use default values set
// by Servo library
attachServo(pin, -1, -1);
}
}
break;
case PIN_MODE_I2C:
if (IS_PIN_I2C(pin)) {
// mark the pin as i2c
// the user must call I2C_CONFIG to enable I2C for a device
Firmata.setPinMode(pin, PIN_MODE_I2C);
}
break;
case PIN_MODE_SERIAL:
#ifdef FIRMATA_SERIAL_FEATURE
serialFeature.handlePinMode(pin, PIN_MODE_SERIAL);
#endif
break;
default:
Firmata.sendString("Unknown pin mode"); // TODO: put error msgs in EEPROM
}
// TODO: save status to EEPROM here, if changed
}
/*
* Sets the value of an individual pin. Useful if you want to set a pin value but
* are not tracking the digital port state.
* Can only be used on pins configured as OUTPUT.
* Cannot be used to enable pull-ups on Digital INPUT pins.
*/
void setPinValueCallback(byte pin, int value)
{
if (pin < TOTAL_PINS && IS_PIN_DIGITAL(pin)) {
if (Firmata.getPinMode(pin) == OUTPUT) {
Firmata.setPinState(pin, value);
digitalWrite(PIN_TO_DIGITAL(pin), value);
}
}
}
void analogWriteCallback(byte pin, int value)
{
if (pin < TOTAL_PINS) {
switch (Firmata.getPinMode(pin)) {
case PIN_MODE_SERVO:
if (IS_PIN_DIGITAL(pin))
servos[servoPinMap[pin]].write(value);
Firmata.setPinState(pin, value);
break;
case PIN_MODE_PWM:
if (IS_PIN_PWM(pin))
analogWrite(PIN_TO_PWM(pin), value);
Firmata.setPinState(pin, value);
break;
}
}
}
void digitalWriteCallback(byte port, int value)
{
byte pin, lastPin, pinValue, mask = 1, pinWriteMask = 0;
if (port < TOTAL_PORTS) {
// create a mask of the pins on this port that are writable.
lastPin = port * 8 + 8;
if (lastPin > TOTAL_PINS) lastPin = TOTAL_PINS;
for (pin = port * 8; pin < lastPin; pin++) {
// do not disturb non-digital pins (eg, Rx & Tx)
if (IS_PIN_DIGITAL(pin)) {
// do not touch pins in PWM, ANALOG, SERVO or other modes
if (Firmata.getPinMode(pin) == OUTPUT || Firmata.getPinMode(pin) == INPUT) {
pinValue = ((byte)value & mask) ? 1 : 0;
if (Firmata.getPinMode(pin) == OUTPUT) {
pinWriteMask |= mask;
} else if (Firmata.getPinMode(pin) == INPUT && pinValue == 1 && Firmata.getPinState(pin) != 1) {
// only handle INPUT here for backwards compatibility
#if ARDUINO > 100
pinMode(pin, INPUT_PULLUP);
#else
// only write to the INPUT pin to enable pullups if Arduino v1.0.0 or earlier
pinWriteMask |= mask;
#endif
}
Firmata.setPinState(pin, pinValue);
}
}
mask = mask << 1;
}
writePort(port, (byte)value, pinWriteMask);
}
}
// -----------------------------------------------------------------------------
/* sets bits in a bit array (int) to toggle the reporting of the analogIns
*/
//void FirmataClass::setAnalogPinReporting(byte pin, byte state) {
//}
void reportAnalogCallback(byte analogPin, int value)
{
if (analogPin < TOTAL_ANALOG_PINS) {
if (value == 0) {
analogInputsToReport = analogInputsToReport & ~ (1 << analogPin);
} else {
analogInputsToReport = analogInputsToReport | (1 << analogPin);
// prevent during system reset or all analog pin values will be reported
// which may report noise for unconnected analog pins
if (!isResetting) {
// Send pin value immediately. This is helpful when connected via
// ethernet, wi-fi or bluetooth so pin states can be known upon
// reconnecting.
Firmata.sendAnalog(analogPin, analogRead(analogPin));
}
}
}
// TODO: save status to EEPROM here, if changed
}
void reportDigitalCallback(byte port, int value)
{
if (port < TOTAL_PORTS) {
reportPINs[port] = (byte)value;
// Send port value immediately. This is helpful when connected via
// ethernet, wi-fi or bluetooth so pin states can be known upon
// reconnecting.
if (value) outputPort(port, readPort(port, portConfigInputs[port]), true);
}
// do not disable analog reporting on these 8 pins, to allow some
// pins used for digital, others analog. Instead, allow both types
// of reporting to be enabled, but check if the pin is configured
// as analog when sampling the analog inputs. Likewise, while
// scanning digital pins, portConfigInputs will mask off values from any
// pins configured as analog
}
/*==============================================================================
* SYSEX-BASED commands
*============================================================================*/
void sysexCallback(byte command, byte argc, byte *argv)
{
byte mode;
byte stopTX;
byte slaveAddress;
byte data;
int slaveRegister;
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 not supported");
return;
}
else {
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);
for (byte i = 2; i < argc; i += 2) {
data = argv[i] + (argv[i + 1] << 7);
wireWrite(data);
}
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
}
else {
// a slave register is NOT specified
slaveRegister = I2C_REGISTER_NOT_SPECIFIED;
data = argv[2] + (argv[3] << 7); // bytes to read
}
readAndReportData(slaveAddress, (int)slaveRegister, data, stopTX);
break;
case I2C_READ_CONTINUOUSLY:
if ((queryIndex + 1) >= I2C_MAX_QUERIES) {
// too many queries, just ignore
Firmata.sendString("too many queries");
break;
}
if (argc == 6) {
// a slave register is specified
slaveRegister = argv[2] + (argv[3] << 7);
data = argv[4] + (argv[5] << 7); // bytes to read
}
else {
// a slave register is NOT specified
slaveRegister = (int)I2C_REGISTER_NOT_SPECIFIED;
data = argv[2] + (argv[3] << 7); // bytes to read
}
queryIndex++;
query[queryIndex].addr = slaveAddress;
query[queryIndex].reg = slaveRegister;
query[queryIndex].bytes = data;
query[queryIndex].stopTX = stopTX;
break;
case I2C_STOP_READING:
byte queryIndexToSkip;
// if read continuous mode is enabled for only 1 i2c device, disable
// read continuous reporting for that device
if (queryIndex <= 0) {
queryIndex = -1;
} else {
queryIndexToSkip = 0;
// if read continuous mode is enabled for multiple devices,
// determine which device to stop reading and remove it's data from
// the array, shifiting other array data to fill the space
for (byte i = 0; i < queryIndex + 1; i++) {
if (query[i].addr == slaveAddress) {
queryIndexToSkip = i;
break;
}
}
for (byte i = queryIndexToSkip; i < queryIndex + 1; i++) {
if (i < I2C_MAX_QUERIES) {
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--;
}
break;
default:
break;
}
break;
case I2C_CONFIG:
delayTime = (argv[0] + (argv[1] << 7));
if (argc > 1 && delayTime > 0) {
i2cReadDelayTime = delayTime;
}
if (!isI2CEnabled) {
enableI2CPins();
}
break;
case SERVO_CONFIG:
if (argc > 4) {
// these vars are here for clarity, they'll optimized away by the compiler
byte pin = argv[0];
int minPulse = argv[1] + (argv[2] << 7);
int maxPulse = argv[3] + (argv[4] << 7);
if (IS_PIN_DIGITAL(pin)) {
if (servoPinMap[pin] < MAX_SERVOS && servos[servoPinMap[pin]].attached()) {
detachServo(pin);
}
attachServo(pin, minPulse, maxPulse);
setPinModeCallback(pin, PIN_MODE_SERVO);
}
}
break;
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;
case EXTENDED_ANALOG:
if (argc > 1) {
int val = argv[1];
if (argc > 2) val |= (argv[2] << 7);
if (argc > 3) val |= (argv[3] << 14);
analogWriteCallback(argv[0], val);
}
break;
case CAPABILITY_QUERY:
Firmata.write(START_SYSEX);
Firmata.write(CAPABILITY_RESPONSE);
for (byte pin = 0; pin < TOTAL_PINS; pin++) {
if (IS_PIN_DIGITAL(pin)) {
Firmata.write((byte)INPUT);
Firmata.write(1);
Firmata.write((byte)PIN_MODE_PULLUP);
Firmata.write(1);
Firmata.write((byte)OUTPUT);
Firmata.write(1);
}
if (IS_PIN_ANALOG(pin)) {
Firmata.write(PIN_MODE_ANALOG);
Firmata.write(10); // 10 = 10-bit resolution
}
if (IS_PIN_PWM(pin)) {
Firmata.write(PIN_MODE_PWM);
Firmata.write(DEFAULT_PWM_RESOLUTION);
}
if (IS_PIN_DIGITAL(pin)) {
Firmata.write(PIN_MODE_SERVO);
Firmata.write(14);
}
if (IS_PIN_I2C(pin)) {
Firmata.write(PIN_MODE_I2C);
Firmata.write(1); // TODO: could assign a number to map to SCL or SDA
}
#ifdef FIRMATA_SERIAL_FEATURE
serialFeature.handleCapability(pin);
#endif
Firmata.write(127);
}
Firmata.write(END_SYSEX);
break;
case PIN_STATE_QUERY:
if (argc > 0) {
byte pin = argv[0];
Firmata.write(START_SYSEX);
Firmata.write(PIN_STATE_RESPONSE);
Firmata.write(pin);
if (pin < TOTAL_PINS) {
Firmata.write(Firmata.getPinMode(pin));
Firmata.write((byte)Firmata.getPinState(pin) & 0x7F);
if (Firmata.getPinState(pin) & 0xFF80) Firmata.write((byte)(Firmata.getPinState(pin) >> 7) & 0x7F);
if (Firmata.getPinState(pin) & 0xC000) Firmata.write((byte)(Firmata.getPinState(pin) >> 14) & 0x7F);
}
Firmata.write(END_SYSEX);
}
break;
case ANALOG_MAPPING_QUERY:
Firmata.write(START_SYSEX);
Firmata.write(ANALOG_MAPPING_RESPONSE);
for (byte pin = 0; pin < TOTAL_PINS; pin++) {
Firmata.write(IS_PIN_ANALOG(pin) ? PIN_TO_ANALOG(pin) : 127);
}
Firmata.write(END_SYSEX);
break;
case SERIAL_MESSAGE:
#ifdef FIRMATA_SERIAL_FEATURE
serialFeature.handleSysex(command, argc, argv);
#endif
break;
}
}
/*==============================================================================
* SETUP()
*============================================================================*/
void systemResetCallback()
{
isResetting = true;
// initialize a defalt state
// TODO: option to load config from EEPROM instead of default
#ifdef FIRMATA_SERIAL_FEATURE
serialFeature.reset();
#endif
if (isI2CEnabled) {
disableI2CPins();
}
for (byte i = 0; i < TOTAL_PORTS; i++) {
reportPINs[i] = false; // by default, reporting off
portConfigInputs[i] = 0; // until activated
previousPINs[i] = 0;
}
for (byte i = 0; i < TOTAL_PINS; i++) {
// pins with analog capability default to analog input
// otherwise, pins default to digital output
if (IS_PIN_ANALOG(i)) {
// turns off pullup, configures everything
setPinModeCallback(i, PIN_MODE_ANALOG);
} else if (IS_PIN_DIGITAL(i)) {
// sets the output to 0, configures portConfigInputs
setPinModeCallback(i, OUTPUT);
}
servoPinMap[i] = 255;
}
// by default, do not report any analog inputs
analogInputsToReport = 0;
detachedServoCount = 0;
servoCount = 0;
/* send digital inputs to set the initial state on the host computer,
* since once in the loop(), this firmware will only send on change */
/*
TODO: this can never execute, since no pins default to digital input
but it will be needed when/if we support EEPROM stored config
for (byte i=0; i < TOTAL_PORTS; i++) {
outputPort(i, readPort(i, portConfigInputs[i]), true);
}
*/
isResetting = false;
}
void setup()
{
Firmata.setFirmwareVersion(FIRMATA_FIRMWARE_MAJOR_VERSION, FIRMATA_FIRMWARE_MINOR_VERSION);
Firmata.attach(ANALOG_MESSAGE, analogWriteCallback);
Firmata.attach(DIGITAL_MESSAGE, digitalWriteCallback);
Firmata.attach(REPORT_ANALOG, reportAnalogCallback);
Firmata.attach(REPORT_DIGITAL, reportDigitalCallback);
Firmata.attach(SET_PIN_MODE, setPinModeCallback);
Firmata.attach(SET_DIGITAL_PIN_VALUE, setPinValueCallback);
Firmata.attach(START_SYSEX, sysexCallback);
Firmata.attach(SYSTEM_RESET, systemResetCallback);
// to use a port other than Serial, such as Serial1 on an Arduino Leonardo or Mega,
// Call begin(baud) on the alternate serial port and pass it to Firmata to begin like this:
// Serial1.begin(57600);
// Firmata.begin(Serial1);
// However do not do this if you are using SERIAL_MESSAGE
Firmata.begin(57600);
while (!Serial) {
; // wait for serial port to connect. Needed for ATmega32u4-based boards and Arduino 101
}
systemResetCallback(); // reset to default config
}
/*==============================================================================
* LOOP()
*============================================================================*/
void loop()
{
byte pin, analogPin;
/* DIGITALREAD - as fast as possible, check for changes and output them to the
* FTDI buffer using Serial.print() */
checkDigitalInputs();
/* STREAMREAD - processing incoming messagse as soon as possible, while still
* checking digital inputs. */
while (Firmata.available())
Firmata.processInput();
// TODO - ensure that Stream buffer doesn't go over 60 bytes
samplingInterval = 1;
currentMillis = millis();
if (currentMillis - previousMillis > samplingInterval) {
previousMillis += samplingInterval;
/* ANALOGREAD - do all analogReads() at the configured sampling interval */
for (pin = 0; pin < TOTAL_PINS; pin++) {
if (IS_PIN_ANALOG(pin) && Firmata.getPinMode(pin) == PIN_MODE_ANALOG) {
analogPin = PIN_TO_ANALOG(pin);
if (analogInputsToReport & (1 << analogPin)) {
analogRead(analogPin);
Firmata.sendAnalog(analogPin, analogRead(analogPin));
}
}
}
// 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, query[i].stopTX);
}
}
}
#ifdef FIRMATA_SERIAL_FEATURE
serialFeature.update();
#endif
}python code:
Code:
import time
import matplotlib as mpl
mpl.use('Qt5Agg')
import matplotlib.pyplot as plt
from pyfirmata import Arduino
board = Arduino('COM6')
board.analog[0].enable_reporting()
stamps = []
t0 = time.perf_counter()
while time.perf_counter()-t0 < 10:
while board.bytes_available():
board.iterate()
stamps.append(time.perf_counter())
plt.plot(stamps, '*')
plt.title('Serial message stamps')The ino code is the same as examples/standardFirmata, but I hardcoded the sampling interval to be 1 ms. And the python code here simply wait for the serial message, timestamp it, and then reads it. If you plot the time stamps of serial messages, you will see clear gaps between chunks of messages, but the total number of messages is correct. So, we didn't lost serial packages, but it's just got chunked and delayed.
This issue is not present for Arduino Uno at 1 Khz, and it's for Teensy at higher sampling rates (>200 hz.)
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