# mcp3201v1701.py tlfong01 2021jan01hkt2258 ***
# *** System Configuration ***
# Rpi4B Thonny Python 3.7.3 (/usr/bin/python3)
# pi@raspberrypi:~ $ date Fri 01 Jan 2021 12:17:54 PM HKT
# pi@raspberrypi:~ $ uname -a Linux raspberrypi 5.4.79-v7l+ #1373 SMP Mon Nov 23 13:27:40 GMT 2020 armv7l GNU/Linux
# *** Test Description ***
# Test 1 - test MCP3201 ADC
# Function - Input an anlog signal to the differential input pins of MCP3201 and read the converted digital value from
# SPI MOSI
# Setup -
# *** Import ***
from datetime import datetime
from time import sleep
import spidev
# ** SPI Setup/Config ***
spiPort00 = spidev.SpiDev()
spiPort00.open(0,0)
spiPort00.max_speed_hz = 100000
spiPort01 = spidev.SpiDev()
spiPort01.open(0,1)
spiPort01.max_speed_hz = 100000
spiPortDict = \
{'SpiPort00': spiPort00,
'SpiPort01': spiPort01,
}
#*** System Functions ***
timeNowLong = str(datetime.now())
timeNowShort = str(datetime.now())[0:16]
# *** SPI System Functions ***
# *** SPI Send/Receive 1/2/3 Bytes ***
def spiSendRecvOneByte(spiBus, sendByte):
sendByteArray = [sendByte]
recvByteArray = spiBus.xfer2(sendByteArray)
return recvByteArray
def spiSendRecvTwoBytes(spiBus, sendByte1, sendByte2):
sendByteArray = [sendByte1, sendByte2]
recvByteArray = spiBus.xfer2(sendByteArray)
return recvByteArray
def spiSendRecvThreeBytes(spiBus, sendByte1, sendByte2, sendByte3):
sendByteArray = [sendByte1, sendByte2, sendByte3]
recvByteArray = spiBus.xfer2(sendByteArray)
return recvByteArray
# *** MCP3201 Config ***
refVoltName = '3.00V'
dummyByte = 0x00
refVoltDict = \
{
'0.00V' : 0.00,
'1.68V' : 1.68,
'10.24V' : 1.024,
'2.048V' : 2.048,
'3.00V' : 3.00,
'3.30V' : 3.30,
'4.096V' : 4.096,
}
# *** MCP3201 Functions ***
def getMcp3201BinaryResults(spiPortName, refVoltName):
spiPort = spiPortDict[spiPortName]
recvArray = spiSendRecvTwoBytes(spiPort, 0x00, 0x00)
print(' spiPortName =', spiPortName)
print(' recvArray =', recvArray)
adcBinaryResults = (((recvArray[0] & 0x3f) << 8) + recvArray[1]) >> 1
print(' adcBinaryResults =', hex(adcBinaryResults))
return adcBinaryResults
def getMcp3201DecimalResults(adcBinaryResults):
adcDecimalResults = (adcBinaryResults / 0xfff) * refVoltDict[refVoltName]
return adcDecimalResults
# *** ADC Functions ***
def testAdc(spiPortName):
print(' MCP3201 ADC Results:')
adcBinaryResults = getMcp3201BinaryResults(spiPortName, refVoltName)
print( 'adcBinaryResults =', adcBinaryResults)
adcDecimalResults = getMcp3201DecimalResults(adcBinaryResults)
#print(' MCP3201 Results in 12 bits binary (expect fff/2~= 0x0800) =', convertTwoByteNumToEightCharStr(adcBinaryResults))
print(' Binary =', hex(adcBinaryResults))
print(' Decimal =', "%.2f" % adcDecimalResults, 'V')
return
# *** Init/Main Function ***
def init():
pass
return
def main():
print('Begin main(), ... tlfong01', timeNowShort)
print(' Begin testMCP3201Adc(), ...')
testAdc('SpiPort00')
print(' End testMCP3201Adc().')
print('End main().')
return
# *** Main()
if __name__ == '__main__':
main()
# *** End of Program ***
# *** Sample Output ***
'''
>>> %Run mcp3201v1601.py
Begin main(), ... tlfong01 2021-01-01 22:56
Begin testMCP3201Adc(), ...
MCP3201 ADC Results:
spiPortName = SpiPort00
recvArray = [15, 231]
adcBinaryResults = 0x7f3
adcBinaryResults = 2035
Binary = 0x7f3
Decimal = 1.49 V
End testMCP3201Adc().
End main().
>>>
'''
# *** End of Sample output ***
