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CommandStation-EX/IO_PCA9685.cpp

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/*
* © 2021, Neil McKechnie. All rights reserved.
*
* This file is part of DCC++EX API
*
* This is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* It is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with CommandStation. If not, see <https://www.gnu.org/licenses/>.
*/
#include "IODevice.h"
#include "I2CManager.h"
#include "DIAG.h"
// REGISTER ADDRESSES
static const byte PCA9685_MODE1=0x00; // Mode Register
static const byte PCA9685_FIRST_SERVO=0x06; /** low byte first servo register ON*/
static const byte PCA9685_PRESCALE=0xFE; /** Prescale register for PWM output frequency */
// MODE1 bits
static const byte MODE1_SLEEP=0x10; /**< Low power mode. Oscillator off */
static const byte MODE1_AI=0x20; /**< Auto-Increment enabled */
static const byte MODE1_RESTART=0x80; /**< Restart enabled */
static const float FREQUENCY_OSCILLATOR=25000000.0; /** Accurate enough for our purposes */
static const uint32_t MAX_I2C_SPEED = 1000000L; // PCA9685 rated up to 1MHz I2C clock speed
// Predeclare helper function
static void writeRegister(byte address, byte reg, byte value);
// Create device driver instance.
void PCA9685::create(VPIN firstVpin, int nPins, I2CAddress i2cAddress, uint16_t frequency) {
if (checkNoOverlap(firstVpin, nPins,i2cAddress)) new PCA9685(firstVpin, nPins, i2cAddress, frequency);
}
// Configure a port on the PCA9685.
bool PCA9685::_configure(VPIN vpin, ConfigTypeEnum configType, int paramCount, int params[]) {
if (configType != CONFIGURE_SERVO) return false;
if (paramCount != 5) return false;
#ifdef DIAG_IO
DIAG(F("PCA9685 Configure VPIN:%u Apos:%d Ipos:%d Profile:%d Duration:%d state:%d"),
vpin, params[0], params[1], params[2], params[3], params[4]);
#endif
int8_t pin = vpin - _firstVpin;
struct ServoData *s = _servoData[pin];
if (s == NULL) {
_servoData[pin] = (struct ServoData *)calloc(1, sizeof(struct ServoData));
s = _servoData[pin];
if (!s) return false; // Check for failed memory allocation
}
s->activePosition = params[0];
s->inactivePosition = params[1];
s->profile = params[2];
s->duration = params[3];
int state = params[4];
if (state != -1) {
// Position servo to initial state
_writeAnalogue(vpin, state ? s->activePosition : s->inactivePosition, 0, 0);
}
return true;
}
// Constructor
PCA9685::PCA9685(VPIN firstVpin, int nPins, I2CAddress i2cAddress, uint16_t frequency) {
_firstVpin = firstVpin;
_nPins = (nPins > 16) ? 16 : nPins;
_I2CAddress = i2cAddress;
// Calculate prescaler value for PWM clock
if (frequency > 1526) frequency = 1526;
else if (frequency < 24) frequency = 24;
prescaler = FREQUENCY_OSCILLATOR / 4096 / frequency;
// To save RAM, space for servo configuration is not allocated unless a pin is used.
// Initialise the pointers to NULL.
for (int i=0; i<_nPins; i++)
_servoData[i] = NULL;
addDevice(this);
// Initialise structure used for setting pulse rate
requestBlock.setWriteParams(_I2CAddress, outputBuffer, sizeof(outputBuffer));
}
// Device-specific initialisation
void PCA9685::_begin() {
I2CManager.begin();
I2CManager.setClock(1000000); // Nominally able to run up to 1MHz on I2C
// In reality, other devices including the Arduino will limit
// the clock speed to a lower rate.
// Initialise I/O module here.
if (I2CManager.exists(_I2CAddress)) {
writeRegister(_I2CAddress, PCA9685_MODE1, MODE1_SLEEP | MODE1_AI);
writeRegister(_I2CAddress, PCA9685_PRESCALE, prescaler);
writeRegister(_I2CAddress, PCA9685_MODE1, MODE1_AI);
writeRegister(_I2CAddress, PCA9685_MODE1, MODE1_RESTART | MODE1_AI);
// In theory, we should wait 500us before sending any other commands to each device, to allow
// the PWM oscillator to get running. However, we don't do any specific wait, as there's
// plenty of other stuff to do before we will send a command.
#if defined(DIAG_IO)
_display();
#endif
} else
_deviceState = DEVSTATE_FAILED;
}
// Device-specific write function, invoked from IODevice::write().
// For this function, the configured profile is used.
void PCA9685::_write(VPIN vpin, int value) {
#ifdef DIAG_IO
DIAG(F("PCA9685 Write VPIN:%u Value:%d"), vpin, value);
#endif
int pin = vpin - _firstVpin;
if (value) value = 1;
struct ServoData *s = _servoData[pin];
if (s != NULL) {
// Use configured parameters
_writeAnalogue(vpin, value ? s->activePosition : s->inactivePosition, s->profile, s->duration);
} else {
/* simulate digital pin on PWM */
_writeAnalogue(vpin, value ? 4095 : 0, Instant | NoPowerOff, 0);
}
}
// Device-specific writeAnalogue function, invoked from IODevice::writeAnalogue().
// Profile is as follows:
// Bit 7: 0=Set PWM to 0% to power off servo motor when finished
// 1=Keep PWM pulses on (better when using PWM to drive an LED)
// Bits 6-0: 0 Use specified duration (defaults to 0 deciseconds)
// 1 (Fast) Move servo in 0.5 seconds
// 2 (Medium) Move servo in 1.0 seconds
// 3 (Slow) Move servo in 2.0 seconds
// 4 (Bounce) Servo 'bounces' at extremes.
//
void PCA9685::_writeAnalogue(VPIN vpin, int value, uint8_t profile, uint16_t duration) {
#ifdef DIAG_IO
DIAG(F("PCA9685 WriteAnalogue VPIN:%u Value:%d Profile:%d Duration:%d %S"),
vpin, value, profile, duration, _deviceState == DEVSTATE_FAILED?F("DEVSTATE_FAILED"):F(""));
#endif
if (_deviceState == DEVSTATE_FAILED) return;
int pin = vpin - _firstVpin;
if (value > 4095) value = 4095;
else if (value < 0) value = 0;
struct ServoData *s = _servoData[pin];
if (s == NULL) {
// Servo pin not configured, so configure now using defaults
s = _servoData[pin] = (struct ServoData *) calloc(sizeof(struct ServoData), 1);
if (s == NULL) return; // Check for memory allocation failure
s->activePosition = 4095;
s->inactivePosition = 0;
s->currentPosition = value;
s->profile = Instant | NoPowerOff; // Use instant profile (but not this time)
}
// Animated profile. Initiate the appropriate action.
s->currentProfile = profile;
uint8_t profileValue = profile & ~NoPowerOff; // Mask off 'don't-power-off' bit.
s->numSteps = profileValue==Fast ? 10 : // 0.5 seconds
profileValue==Medium ? 20 : // 1.0 seconds
profileValue==Slow ? 40 : // 2.0 seconds
profileValue==Bounce ? sizeof(_bounceProfile)-1 : // ~ 1.5 seconds
duration * 2 + 1; // Convert from deciseconds (100ms) to refresh cycles (50ms)
s->stepNumber = 0;
s->toPosition = value;
s->fromPosition = s->currentPosition;
}
// _read returns true if the device is currently in executing an animation,
// changing the output over a period of time.
int PCA9685::_read(VPIN vpin) {
if (_deviceState == DEVSTATE_FAILED) return 0;
int pin = vpin - _firstVpin;
struct ServoData *s = _servoData[pin];
if (s == NULL)
return false; // No structure means no animation!
else
return (s->stepNumber < s->numSteps);
}
void PCA9685::_loop(unsigned long currentMicros) {
for (int pin=0; pin<_nPins; pin++) {
updatePosition(pin);
}
delayUntil(currentMicros + refreshInterval * 1000UL);
}
// Private function to reposition servo
// TODO: Could calculate step number from elapsed time, to allow for erratic loop timing.
void PCA9685::updatePosition(uint8_t pin) {
struct ServoData *s = _servoData[pin];
if (s == NULL) return; // No pin configuration/state data
if (s->numSteps == 0) return; // No animation in progress
if (s->stepNumber == 0 && s->fromPosition == s->toPosition) {
// Go straight to end of sequence, output final position.
s->stepNumber = s->numSteps-1;
}
if (s->stepNumber < s->numSteps) {
// Animation in progress, reposition servo
s->stepNumber++;
if ((s->currentProfile & ~NoPowerOff) == Bounce) {
// Retrieve step positions from array in flash
byte profileValue = GETFLASH(&_bounceProfile[s->stepNumber]);
s->currentPosition = map(profileValue, 0, 100, s->fromPosition, s->toPosition);
} else {
// All other profiles - calculate step by linear interpolation between from and to positions.
s->currentPosition = map(s->stepNumber, 0, s->numSteps, s->fromPosition, s->toPosition);
}
// Send servo command
writeDevice(pin, s->currentPosition);
} else if (s->stepNumber < s->numSteps + _catchupSteps) {
// We've finished animation, wait a little to allow servo to catch up
s->stepNumber++;
} else if (s->stepNumber == s->numSteps + _catchupSteps
&& s->currentPosition != 0) {
#ifdef IO_SWITCH_OFF_SERVO
if ((s->currentProfile & NoPowerOff) == 0) {
// Wait has finished, so switch off PWM to prevent annoying servo buzz
writeDevice(pin, 0);
}
#endif
s->numSteps = 0; // Done now.
}
}
// writeDevice takes a pin in range 0 to _nPins-1 within the device, and a value
// between 0 and 4095 for the PWM mark-to-period ratio, with 4095 being 100%.
void PCA9685::writeDevice(uint8_t pin, int value) {
#ifdef DIAG_IO
DIAG(F("PCA9685 I2C:%s WriteDevice Pin:%d Value:%d"), _I2CAddress.toString(), pin, value);
#endif
// Wait for previous request to complete
uint8_t status = requestBlock.wait();
if (status != I2C_STATUS_OK) {
_deviceState = DEVSTATE_FAILED;
DIAG(F("PCA9685 I2C:%s failed %S"), _I2CAddress.toString(), I2CManager.getErrorMessage(status));
} else {
// Set up new request.
outputBuffer[0] = PCA9685_FIRST_SERVO + 4 * pin;
outputBuffer[1] = 0;
outputBuffer[2] = (value == 4095 ? 0x10 : 0); // 4095=full on
outputBuffer[3] = value & 0xff;
outputBuffer[4] = value >> 8;
I2CManager.queueRequest(&requestBlock);
}
}
// Display details of this device.
void PCA9685::_display() {
DIAG(F("PCA9685 I2C:%s Configured on Vpins:%u-%u %S"), _I2CAddress.toString(), (int)_firstVpin,
(int)_firstVpin+_nPins-1, (_deviceState==DEVSTATE_FAILED) ? F("OFFLINE") : F(""));
}
// Internal helper function for this device
static void writeRegister(byte address, byte reg, byte value) {
I2CManager.write(address, 2, reg, value);
}
// Profile for a bouncing signal or turnout
// The profile below is in the range 0-100% and should be combined with the desired limits
// of the servo set by _activePosition and _inactivePosition. The profile is symmetrical here,
// i.e. the bounce is the same on the down action as on the up action. First entry isn't used.
const uint8_t FLASH PCA9685::_bounceProfile[30] =
{0,2,3,7,13,33,50,83,100,83,75,70,65,60,60,65,74,84,100,83,75,70,70,72,75,80,87,92,97,100};
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