MCP3208 testing noytes

Now I am trying to do 8 channels ADC one after another, with inputs 2.5V, 1.4V, 3.3V, and 0V at channels 0 to 7.

I found only channels 0, 4, 5 give correct results.  But when I tested channel 1 alone, then it gives correct results.

So it appears that there is some sort of timing problem.


pi@raspberrypi ~/fongtoy $ sudo python fongtoy.py

*** Start Program - FongToy v1.25 tlfong01 2013may28 ***

Analog voltage at channel number  0  =  2.498
Analog voltage at channel number  1  =  59.751
Analog voltage at channel number  2  =  60.689
Analog voltage at channel number  3  =  0.0
Analog voltage at channel number  4  =  3.333
Analog voltage at channel number  5  =  1.37
Analog voltage at channel number  6  =  59.843
Analog voltage at channel number  7  =  57.344

*** Stop Program ***

pi@raspberrypi ~/fongtoy $ sudo python fongtoy.py

*** Start Program - FongToy v1.25 tlfong01 2013may28 ***

Analog voltage at channel number  1  =  2.405

*** Stop Program ***

pi@raspberrypi ~/fongtoy $ date
Tue May 28 04:46:49 UTC 2013

# fongtoy v1.25 tlfong01 2013may28

ProgramTitle = "FongToy v1.25 tlfong01 2013may28"

import sys 

import time 

import smbus 

import pdb 

import spidev 

import wiringpi

import wiringpi2

import RPIO as GPIO  

from RPIO import PWM 

from enum import Enum 

from subprocess import call

import ftgpio

import ftprint

import ftspi

import ftiox

import fteeprom

import ftguzuntypi

import ftdemux

import fttest

import ftadc

# *** Main program ***

# *** Start program message ***

ftprint.StartProgram(ProgramTitle)

# *** Troubleshooting functions ***

# *** GPIO tests v1.3 tlfong01 2013may23 ***

# ftgpio.TestLed()

# ftgpio.TestBuzzer()

# ftgpio.TestButtonEchoBuzzer()

# ftgpio.TestButtonEchoLed()

# *** SPI Tests v1.3 tlfong01 2013may23 ***

# ftspi.TestSpiLoopBack(spiChannelNumber = 0, spiChipEnableNumber = 1, testDataByte = 0x55, testCount = 1000, testTime = 0.001)

# ftiox.TestMcp23s17BlinkLed(spiChannelNumber = 0, spiChipEnableNumber = 0, spiChipSubAddress = 0)

# fteeprom.TestWriteReadEepormDataByte(spiChannelNumber = 0, spiChipEnableNumber = 1, startAddress = 0x0410, testDataByte = 0x55)

# ftguzuntypi.TestGuzuntyPi4digit7segmentLedModule(spiChannelNumber = 0, spiChipEnableNumber = 1)

# ftdemux.TestSelectSpiSlaveDevice(spiChannelNumber = 0, spiChipEnableNumber = 0, spiIoxSubAddress = 0, spiSlaveDeviceNumber = 5)

# fttest.TestDemuxEeprom(mcp23s17SubAddress = 0, eepromDemuxAddress = 2, testStartAddress = 0x0123, testWriteDataByte = 0x5a)

# fttest.TestDemuxEeprom(mcp23s17SubAddress = 0, eepromDemuxAddress = 1, testStartAddress = 0x0123, testWriteDataByte = 0x3b)

# fttest.TestDemuxEeprom(mcp23s17SubAddress = 0, eepromDemuxAddress = 0, testStartAddress = 0x0123, testWriteDataByte = 0x3b)

# *** Current test functions ***

# ftiox.TestMcp23s17BlinkLed(spiChannelNumber = 0, spiChipEnableNumber = 0, spiChipSubAddress = 0)

# ftdemux.TestSelectSpiSlaveDevice(spiChannelNumber = 0, spiChipEnableNumber = 0, spiIoxSubAddress = 0, spiSlaveDeviceNumber = 5)

# fttest.TestDemuxEeprom(mcp23s17SubAddress = 0, eepromDemuxAddress = 0, testStartAddress = 0x0123, testWriteDataByte = 0x3b)

# fttest.TestDemuxEeprom(mcp23s17SubAddress = 0, eepromDemuxAddress = 1, testStartAddress = 0x0411, testWriteDataByte = 0x4c)

# fttest.TestDemuxGuzuntyClock(mcp23s17SubAddress = 0, guzuntyClockDemuxAddress = 2, secondCount = 10)

# fttest.TestMcp320103(testTime = 0.1, testCount = 10)

# fttest.TestMcp320103(testTime = 0.01, testCount = 100)

# fttest.TestMcp320103(testTime = 0.05, testCount = 50)

# fttest.TestMcp320103(testTime = 0.1, testCount = 1)

# ftspi.TestSpiLoopBackV01(spiChannelNumber = 0, spiChipEnableNumber = 1, testDataByte = 0x55, testTime = 0.001, testCount = 60000)

# ftadc.TestMcp320101()

# ftadc.TestMcp3208v01()

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 0) 

ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 1) 

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 2) 

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 3) 

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 4) 

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 5)

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 6) 

#ftadc.TestMcp3208v02(inputMode = 1, channelNumber = 7) 

# *** Stop program message ***

ftprint.StopProgram()

#.END

# ftadc.py v1.4 tlfong01 2013may27

import spidev

import time

import ftprint

import ftspi

# *****************************************************************************

# Function - TestAdcMcp3208 

# ***************************************************************************** 

def TestMcp3208v02(inputMode, channelNumber): # v0.2 tlfong01 2013may28

    # ftprint.PrintDoubleSpaceLine("*** Start testing MCP3208 ADC ***")   

    spiChannel = spidev.SpiDev() 

    spiChannel.open(0, 1)  

    CommonMode = 0

    DifferentialMode = 1

    SingleEndModeFirstByte = 0x06

    DifferentialModeFirstByte = 0x04

    controlTripleByte = [0x00, 0x00, 0x00]

    resultTripleByte = [0x00, 0x00, 0x00]

    controlTripleByte[0] = SingleEndModeFirstByte | (channelNumber >> 2)

    controlTripleByte[1] = channelNumber << 6

    controlTripleByte[2] = 0x00 # don't care, actually

    resultTripleByte = spiChannel.xfer2(controlTripleByte) 

    # ftprint.PrintEightBitPattern("ADC output byte 0 = ", resultTripleByte[0])

    # ftprint.PrintEightBitPattern("ADC output byte 1 = ", resultTripleByte[1])

    # ftprint.PrintEightBitPattern("ADC output byte 2 = ", resultTripleByte[2])

    resultDecimal =  (resultTripleByte[1] * (2 ** 8)) + (resultTripleByte[2])

    resultVoltage = (float(resultDecimal) / 4096) * 4.096 

    

    print "Analog voltage at channel number ", channelNumber, " = ", resultVoltage

    spiChannel.close() 

    # ftprint.PrintDoubleSpaceLine("*** Stop testing MCP3208 ***")

def TestMcp3208v01(): # v0.1 tlfong01 2013may27

    ftprint.PrintDoubleSpaceLine("*** Start testing MCP3208 ADC ***")   

    spiGuzuntyPi = spidev.SpiDev() 

    spiGuzuntyPi.open(0, 1)  

    controlTripleByteSingleEndChannel0 = [0x06, 0x00, 0x00]

    resultTripleByte = [0x00, 0x00, 0x00]

    resultTripleByte = spiGuzuntyPi.xfer2(controlTripleByteSingleEndChannel0) 

    ftprint.PrintEightBitPattern("ADC output byte 0 = ", resultTripleByte[0])

    ftprint.PrintEightBitPattern("ADC output byte 1 = ", resultTripleByte[1])

    ftprint.PrintEightBitPattern("ADC output byte 2 = ", resultTripleByte[2])

    resultDecimal =  (resultTripleByte[1] * (2 ** 8)) + (resultTripleByte[2])

    resultVoltage = (float(resultDecimal) / 4096) * 4.096 

    

    print "Analog voltage = ", resultVoltage

    spiGuzuntyPi.close() 

    ftprint.PrintDoubleSpaceLine("*** Stop testing MCP3208 ***") 

# *****************************************************************************

# Function - TestAdcMcp3201() 

# Description - 

# Sample call - 

# ***************************************************************************** 

def TestMcp320101(): #v1.3 tlfong01 2013may23

    ftprint.PrintDoubleSpaceLine("*** Start testing MCP3201 ADC ***")   

    spiGuzuntyPi = spidev.SpiDev() 

    spiGuzuntyPi.open(0, 1)  

    DummyDoubleByteList = [0x00, 0x00]

    adcOutputDoubleByteList = [0x55, 0x55]

    adcOutputDoubleByteList = spiGuzuntyPi.xfer2(DummyDoubleByteList) 

    ftprint.PrintEightBitPattern("ADC output byte 1 = ", adcOutputDoubleByteList[0])

    ftprint.PrintEightBitPattern("ADC output byte 2 = ", adcOutputDoubleByteList[1])

    adcDecimalValue = (adcOutputDoubleByteList[1] >> 1) + (adcOutputDoubleByteList[0] * (2 ** 7))

    # adcAnalogVoltage = (float(adcDecimalValue) / 4096) * 4.10 # without half voltage divider

    adcAnalogVoltage = ((float(adcDecimalValue) / 4096) * 4.10) * 2 # with half voltage divider

    

    print "Analog voltage = ", adcAnalogVoltage

    spiGuzuntyPi.close() 

    ftprint.PrintDoubleSpaceLine("*** Stop testing MCP3201 ***") 

# ***************************************************************************** 

# Function - TestAdcMcp3201() 

# Description - 

# Sample call - 

# Sample output -

# *** Start testing MCP3201 ADC ***

# ADC output byte 1 =  00001011

# ADC output byte 2 =  11111111

# Analog voltage   3.07299804687

# *** Stop testing MCP3201 ***

# ***************************************************************************** 

def TestMcp320102(spiChannel):

    ftprint.PrintDoubleSpaceLine("*** Start testing MCP3201 ADC ***")   

    DummyDoubleByteList = [0x00, 0x00]

    adcOutputDoubleByteList = [0x55, 0x55]

    adcOutputDoubleByteList = spiChannel.xfer2(DummyDoubleByteList) 

    ftprint.PrintEightBitPattern("ADC output byte 1 = ", adcOutputDoubleByteList[0])

    ftprint.PrintEightBitPattern("ADC output byte 2 = ", adcOutputDoubleByteList[1])

    adcDecimalValue = (adcOutputDoubleByteList[1] >> 1) + (adcOutputDoubleByteList[0] * (2 ** 7))

    # adcAnalogVoltage = (float(adcDecimalValue) / 4096) * 4.10 # without half voltage divider

    adcAnalogVoltage = ((float(adcDecimalValue) / 4096) * 4.10) * 2 # with half voltage divider

    

    print "Analog voltage = ", adcAnalogVoltage

    ftprint.PrintDoubleSpaceLine("*** Stop testing MCP3201 ***") 

def TestMcp320103(spiChannel, testTime, testCount):

    ftprint.PrintDoubleSpaceLine("*** Start testing MCP3201 ADC ***")   

    for i in range(testCount):

        DummyDoubleByteList = [0x00, 0x00]

        adcOutputDoubleByteList = [0x55, 0x55]

        adcOutputDoubleByteList = spiChannel.xfer2(DummyDoubleByteList) 

time.sleep(testTime)

    ftprint.PrintEightBitPattern("ADC output byte 1 = ", adcOutputDoubleByteList[0])

    ftprint.PrintEightBitPattern("ADC output byte 2 = ", adcOutputDoubleByteList[1])

    adcDecimalValue = (adcOutputDoubleByteList[1] >> 1) + (adcOutputDoubleByteList[0] * (2 ** 7))

    # adcAnalogVoltage = (float(adcDecimalValue) / 4096) * 4.10 # without half voltage divider

    adcAnalogVoltage = ((float(adcDecimalValue) / 4096) * 4.10) * 2 # with half voltage divider

    

    print "Analog voltage = ", adcAnalogVoltage

    ftprint.PrintDoubleSpaceLine("*** Stop testing MCP3201 ***") 

# .END

.END