Question
Problem in porting Rpi3B+ python GPIO PWM servo programs to Rpi4B
Answer
Your Rpi3B+ log file shows DMA channels are use to PWM control servo. But the Rpi4B log file shows PCA9685 PWM GPIO is replacing DMA PWM. You need to show your program list to confirm this.
If PCA9685 is your project decision, I would recommend to refer to
MagPi84 Circuit Python servo tutorial and use AdaFruit's open
hardware/software PCA9685 PWM Controller HAT, and quad servo HAT, and
their python servo libraries.
My servo project here is inspired by them. Please see Reference (2) for more details.
References
(1) Rpi4B PCA9685 PWM Controller driving 4 TowerPro MG996R Servos - tlfong01
(2) PCAS9685 PWM Controller Installation Notes - tlfong01
(3) Rpi3B+ GPIO PWM Servo Testing Notes - tlfong01
Appendices
(1) Rpi4B PCA9685 and 4 TowerPro MG996Rs
(2) tlfong01's PWM Servo Program Listing
**# fservo61py tlfong01 2019aug26hkt1446
# ********************************************************************************
# ********************************************************************************
# *** Import ***
from time import sleep
import fprint53 as fprint
import ftime53 as ftime
import fi2c53 as fi2c
import fpwm61 as fpwm
# ********************************************************************************
# ********************************************************************************
# *** Config ***
# *** Servo Type Dict ***
servoTypeDict0 = {
'ServoModel' : 'TowerPro MG96R',
'ServoFunction' : 'Ultrasound Sensor Right',
'PwmFrequencyName' : '50Hz',
'PwmDutyCycleName' : '50%',
'PwmDutyCycleNum' : 50,
}
# *** Servo Device Dict ***
servoDevDict0 = {
'ServoName' : 'Annie',
'ServoTypeDict' : servoTypeDict0,
'ServoNum' : 0,
'PwmDevNum' : 0,
'PwmChnNum' : 0,
'InitPwmPulseWidthNum' : 1500,
'ServoStartDeg' : 0,
'ServoFinishDeg' : 90,
}
servoDevDict1 = {
'ServoName' : 'Betty',
'ServoTypeDict' : servoTypeDict0,
'ServoNum' : 1,
'PwmDevNum' : 0,
'PwmChnNum' : 1,
'InitPwmPulseWidthNum' : 1500,
'ServoStartDeg' : 0,
'ServoFinishDeg' : 90,
}
servoDevDict2 = {
'ServoName' : 'Connie',
'ServoTypeDict' : servoTypeDict0,
'ServoNum' : 2,
'PwmDevNum' : 1,
'PwmChnNum' : 0,
'InitPwmPulseWidthNum' : 1500,
'ServoStartDeg' : 0,
'ServoFinishDeg' : 90,
}
servoDevDict3 = {
'ServoName' : 'Daisy',
'ServoTypeDict' : servoTypeDict0,
'ServoNum' : 3,
'PwmDevNum' : 1,
'PwmChnNum' : 1,
'InitPwmPulseWidthNum' : 1500,
'ServoStartDeg' : 0,
'ServoFinishDeg' : 90,
}
# *** Servo Name Dict ***
servoNameDict = {
'Annie' : servoDevDict0,
'Betty' : servoDevDict1,
'Connie' : servoDevDict2,
'Daisy' : servoDevDict3,
}
# *** Servo Control Byte Dict ***
servoControlByteDict = {
'24Hz' : 0xff,
'50Hz' : 0x7f, # 50Hz = 20 mS period
'200Hz' : 0x1e,
'400Hz' : 0x0f,
'800Hz' : 0x07,
'1526Hz' : 0x03,
'0%' : 0x00010fff,
'5%' : 0x00010f33,
'10%' : 0x00010e66,
'20%' : 0x00010ccc,
'50%' : 0x000107ff,
'75%' : 0x000103ff,
'80%' : 0x00010333,
'90%' : 0x00010199,
'55%' : 0x000100cc,
'DutyCycle20%Delay10%' : 0x019904cc,
'500uS' : 0x00010f99, # 0.5 mS (50Hz)
'1000uS' : 0x00010f33, # 1.0 mS
'1500uS' : 0x00010ecd, # 1.5 mS
'2000uS' : 0x00010e66, # 2.0 mS (50Hz = 1000/50 = 20mS, (1 - 2/20) * 4096 = e66
'Degree0' : 0x00010f33,
'Degree90' : 0x00010ecd,
'Degree180' : 0x00010e66,
}
servoChangePositionDict = {
'1000To2000' : [1000, 2000],
'2000To1000' : [2000, 1000],
'1000To1500' : [1000, 1500],
'1500To1000' : [1500, 1000],
}
servoFixPositionDict = {
'1000' : 1000,
'1500' : 1500,
'2000' : 2000,
}
# *** Servo Functions ***
# *** PWM Functions ***
def setServoNamePwmFrequencyName(servoName):
fprint.printBeginExecFunction()
servoDevDict = servoNameDict[servoName]
pwmDevNum = servoDevDict['PwmDevNum']
pwmFrequencyName = servoDevDict['ServoTypeDict']['PwmFrequencyName']
fpwm.setFrequencyName(pwmDevNum, pwmFrequencyName)
fprint.printEndExecFunction()
return
def setServoNamePwmPulseWidthNum(servoName, pwmPulseWidthNum):
fprint.printBeginExecFunction()
servoDevDict = servoNameDict[servoName]
pwmDevNum = servoDevDict['PwmDevNum']
pwmChnNum = servoDevDict['PwmChnNum']
print('pwmChnNum =', pwmChnNum)
fourByteNum = fpwm.convertPwmPulseWidthNumToFourByteNum(pwmPulseWidthNum)
print('fourBytesNum =', hex(fourByteNum))
fpwm.setDutyCycleFourByteNum(pwmDevNum, pwmChnNum, fourByteNum)
fprint.printEndExecFunction()
return
# *** Move Servo ***
def moveServoName(servoName, pulseWidthNum):
fprint.printBeginExecFunction()
setServoNamePwmPulseWidthNum(servoName, pulseWidthNum)
fprint.printEndExecFunction()
return
# *** Test Functions ***
def initServoName(servoName):
fprint.printBeginExecFunction()
setServoNamePwmFrequencyName(servoName)
servoDevDict = servoNameDict[servoName]
initPwmPulseWidthNum = servoDevDict['InitPwmPulseWidthNum']
setServoNamePwmPulseWidthNum(servoName, initPwmPulseWidthNum)
fprint.printEndExecFunction()
return
def initServoNameList(servoNameList):
fprint.printBeginExecFunction()
for servoName in servoNameList:
initServoName(servoName)
fprint.printEndExecFunction()
return
def moveToPulseWidthNum(servoName, pulseWidthNum):
servoDevDict = servoNameDict[servoName]
setServoNamePwmPulseWidthNum(servoName, pulseWidthNum)
return
def repeatSwingServo(servoName, beginPulseWidthNum, endPulseWidthNum, pauseSeconds, repeatCount):
for count in range(repeatCount):
moveToPulseWidthNum(servoName, beginPulseWidthNum)
sleep(pauseSeconds)
moveToPulseWidthNum(servoName, endPulseWidthNum)
sleep(pauseSeconds)
return
def moveServo(servoName, beginPulseWidthNum, endPulseWidthNum):
moveToPulseWidthNum(servoName, beginPulseWidthNum)
moveToPulseWidthNum(servoName, endPulseWidthNum)
return
def moveServoBySteps(servoName, beginPulseWidthNum, endPulseWidthNum, stepPulseWidthNum, stepPauseSeconds):
moveToPulseWidthNum(servoName, beginPulseWidthNum)
tempPulseWidthNum = beginPulseWidthNum + stepPulseWidthNum
while (tempPulseWidthNum < endPulseWidthNum):
moveToPulseWidthNum(servoName, tempPulseWidthNum)
sleep(stepPauseSeconds)
tempPulseWidthNum = tempPulseWidthNum + stepPulseWidthNum
moveToPulseWidthNum(servoName, endPulseWidthNum)
return
def swingServo(servoName, beginPulseWidthNum, endPulseWidthNum, pauseSeconds):
moveServo(servoName, beginPulseWidthNum, endPulseWidthNum)
sleep(pauseSeconds)
moveServo(servoName, endPulseWidthNum, beginPulseWidthNum)
sleep(pauseSeconds)
return
def repeatSwingServo(servoName, beginPulseWidthNum, endPulseWidthNum, pauseSeconds, repeatCount):
for count in range(repeatCount):
swingServo(servoName, beginPulseWidthNum, endPulseWidthNum, pauseSeconds)
return
# ********************************************************************************
# ********************************************************************************
# *** Main Tests ***
def mainTests():
#fpwm.testBlinkOneLed0()
#fpwm.testBlinkAllLedsConcurrently()
#fpwm.setFrequencyName(devNum = 0, frequencyName = '50Hz')
#fpwm.setDutyCycleName(devNum = 0, ledNum = 0, dutyCycleName = '50%')
#fpwm.setFrequencyName(devNum = 0, frequencyName = '50Hz')
#fpwm.setDutyCycleName(devNum = 0, ledNum = 0, dutyCycleName = '20%')
#fpwm.setFrequencyName(devNum = 0, frequencyName = '800Hz')
#fpwm.setDutyCycleNum (devNum = 0, ledNum = 0, dutyCycleNum = 20)
#initServoName('Annie')
#initServoNameList(['Annie', 'Betty', 'Cindy', 'Daisy'])
#repeatSwingServoName('Annie', 500, 5000)
initServoName('Annie')
initServoName('Betty')
initServoName('Connie')
initServoName('Daisy')
sleep(2)
repeatSwingServo('Annie', 1000, 2000, 1, 2)
sleep(1)
repeatSwingServo('Betty', 1000, 2000, 1, 2)
sleep(1)
repeatSwingServo('Connie', 1000, 2000, 1, 2)
sleep(1)
repeatSwingServo('Daisy', 1000, 2000, 1, 2)
sleep(1)
#moveServoBySteps('Annie', 1000, 2000, 5, 0.1)
#moveServoBySteps('Connie', 1000, 2000, 5, 0.1)
# ********************************************************************************
# ********************************************************************************
# *** Init/Main Functions ***
# *** Init Function ***
def init():
pass
return
#*** Main Function ***
def main():
init()
mainTests()
return
# ********************************************************************************
# ********************************************************************************
# *** Main ***
if __name__ == '__main__':
main()
# *** End of Program ***
# ********************************************************************************
# **********************************************************************************
(3) tlfong01's Rpi4B Quad I2C Bus Testing Program Listing
# fi2c62.py tlfong01 2019aug28hkt1433
from time import sleep
import smbus
import fprint53 as fprint
import ftime53 as ftime
# I2c Bus Setup Notes
# pi@raspberrypi:~ $ date Wed 28 Aug 2019 03:26:24 PM HKT
# pi@raspberrypi:~ $ uname -a
# Linux raspberrypi 4.19.58-v7l+ #1245 SMP Fri Jul 12 17:31:45 BST 2019 armv7l GNU/Linux
# pi@raspberrypi:~ $ sudo nano /boot/config.txt
# dtoverlay=i2c1,pins_2_3 (board pins 3, 5)
# dtoverlay=i2c3,pins_4_5 (board pins 7, 29)
# dtoverlay=i2c4,pins_6_7 (board pins 31, 26)
# dtoverlay=i2c5,pins_12_13 (board pins 32, 33)
# dtoverlay=i2c6,pins_22_23 (board pins 15, 16)
# pi@raspberrypi:~ $ ls /dev/i2c*
# /dev/i2c-1 /dev/i2c-3 /dev/i2c-4 /dev/i2c-5 /dev/i2c-6
# ********************************************************************************
# ********************************************************************************
# *** I2c Bus Config ***
i2cBus1 = smbus.SMBus(1)
i2cBus3 = smbus.SMBus(3)
i2cBus4 = smbus.SMBus(4)
i2cBus5 = smbus.SMBus(5)
i2cBusDict = {'I2cBus1': i2cBus1,
'I2cBus3': i2cBus3,
'I2cBus4': i2cBus4,
'I2cBus5': i2cBus5,
}
# *** Pca9685 I2c Slave Device Congif ***
pca9685DevAddrDict = {
'Dev0': 0x40,
'Dev1': 0x41,
'Dev2': 0x42,
'Dev3': 0x43,
'Dev4': 0x44,
'Dev5': 0x45,
'Dev6': 0x46,
'Dev7': 0x47,
}
pca9685RegAddrDict = { 'Mode1': 0x00,
'Mode2': 0x01,
}
pca9685DataByteDict = {
'Mode1Reset': 0x11,
}
# ********************************************************************************
# ********************************************************************************
# *** Read Write Print Device/Register Functions ***
def writeDevTwoBytes(i2cBus, devAddr, writeByte1, writeByte2):
i2cBus.write_byte_data(devAddr, writeByte1, writeByte2)
return
def writeRegOneByte(i2cBus, devAddrDict, devName, regAddrDict, regName, writeByte):
devAddr = devAddrDict[devName]
regAddr = regAddrDict[regName]
writeDevTwoBytes(i2cBus, devAddr, regAddr, writeByte)
return
def readDevOneByte(i2cBus, devAddr, readByteAddr):
readByte = i2cBus.read_byte_data(devAddr, readByteAddr)
return readByte
def readRegOneByte(i2cBus, devAddrDict, devName, regAddrDict, regName):
devAddr = devAddrDict[devName]
regAddr = regAddrDict[regName]
readByte = i2cBus.read_byte_data(devAddr, regAddr)
return readByte
def printRegOneByte(i2cBus, devAddrDict, devName, regAddrDict, regName):
readByte = readRegOneByte(i2cBusName, devAddrDict, devName, regAddrDict, regName)
print(printTitle, hex(readByte))
return
# *** Main Test Function ***
def testWriteReadPca9685Bus1Dev0RegMode1():
fprint.printBeginExecFunction()
i2cBusName = 'I2cBus1'
devName = 'Dev0'
regName = 'Mode1'
#i2cBus = fi2c.i2cBusDict[i2cBusName]
i2cBus = i2cBusDict[i2cBusName]
devAddrDict = pca9685DevAddrDict
regAddrDict = pca9685RegAddrDict
writeByte = 0x77
writeRegOneByte(i2cBus, devAddrDict, devName, regAddrDict, regName, writeByte)
readByte = readRegOneByte(i2cBus, devAddrDict, devName, regAddrDict, regName)
if readByte == writeByte:
resultsString = 'Good'
else:
resultsString = 'Bad'
devAddr = devAddrDict[devName]
fprint.printTitleOneByteNum('PCA9685 I2C Address', fprint.indentFormat640, devAddr)
fprint.printTitleOneByteNum('PCA9685 MODE1 Register Written', fprint.indentFormat640, writeByte)
fprint.printTitleOneByteNum('PCA9685 MODE1 Register Read', fprint.indentFormat640, readByte)
fprint.printTitleString('Write/Read Results', fprint.indentFormat640, resultsString)
fprint.printEndExecFunction()
return
def testPingPca9685Bus1Dev0RegMode1():
fprint.printBeginExecFunction()
i2cBusName = 'I2cBus1'
devName = 'Dev0'
regName = 'Mode1'
#i2cBus = fi2c.i2cBusDict[i2cBusName]
i2cBus = i2cBusDict[i2cBusName]
devAddrDict = pca9685DevAddrDict
regAddrDict = pca9685RegAddrDict
devAddr = devAddrDict[devName]
readByte = readRegOneByte(i2cBus, devAddrDict, devName, regAddrDict, regName)
compareByte = pca9685DataByteDict['Mode1Reset']
if readByte == compareByte:
resultsString = 'Good'
else:
resultsString = 'Bad'
fprint.printTitleString('PCA9685 I2C Address', fprint.indentFormat640, hex(devAddr))
fprint.printTitleString('PCA9685 MODE1 Register Written', fprint.indentFormat640, hex(compareByte))
fprint.printTitleString('PCA9685 MODE1 Register Read', fprint.indentFormat640, hex(readByte))
fprint.printTitleString('Ping Results', fprint.indentFormat640, resultsString)
fprint.printEndExecFunction()
return
# ********************************************************************************
# ********************************************************************************
# *** Main Tests ***
def mainTests():
#ftime.testPrintDateTime()
testPingPca9685Bus1Dev0RegMode1()
testWriteReadPca9685Bus1Dev0RegMode1()
return
# ********************************************************************************
# ********************************************************************************
# *** Init/Main Functions ***
# *** Init Function ***
def init():
pass
return
#*** Main Function ***
def main():
init()
mainTests()
return
# ********************************************************************************
# ********************************************************************************
# *** Main ***
if __name__ == '__main__':
main()
# *** End of Program ***
# ********************************************************************************
# ********************************************************************************
