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AFE4300: Is it possible to verify if the microcontroller burned out?

Maxime Traore
Prodigy 30 points
Part Number: AFE4300

Hi,

I am working on the AFE4300 to make bioimpedance measurements and to do so I am working with a Raspberry Pi 4.

The problem I am currently experiencing concerns the reading of the registers. I am sending you the python code I wrote.

import spidev #bibliotheque SPI (protocole de communication entre le Raspebrry et l'AFE)
import wiringpi
import RPi.GPIO as GPIO

# Adresses des registres de l'AFE4300 (Cf. datasheet AFE: Register Map)

ADC_DATA_RESULT = 0x00
ADC_CONTROL_REGISTER1 = 0x01
MISC_REGISTER1 = 0x02
MISC_REGISTER2 = 0x03
DEVICE_CONTROL1 = 0x09
ISW_MUX = 0x0A
VSENSE_MUX = 0x0B
IQ_MODE_ENABLE = 0x0C
WEIGHT_SCALE_CONTROL = 0x0D
BCM_DAC_FREQ = 0x0E
DEVICE_CONTROL2 = 0x0F
ADC_CONTROL_REGISTER2 = 0x10
MISC_REGISTER3 = 0x1A

# Definition des pins

wiringpi.wiringPiSetupPhys() # La numerotation des broches du Raspberry est la numerotation physique

# Pin CLK

wiringpi.pinMode(12,2) # broche 12 en PWM (le signal d'horloge)

wiringpi.pwmSetMode(0) # 0: frequence constante
wiringpi.pwmSetRange(10)
wiringpi.pwmSetClock(2) # la frequence est donne par f = 19.2 MHz / (pwmClock x pwmRange), on veut une freq de 1 MHz

wiringpi.pwmWrite(12,5) # rapport cyclique par rapport au Range (10) => 5 equivaut a un rapport cyclique (duty cycle) 50 %

# Pin RESET

wiringpi.pinMode(11,1) # broche 11 en sortie
wiringpi.digitalWrite(11,0) # broche 11 etat bas, ce qui correspond a effectuer un reset (obligatoire) de l'AFE

wiringpi.delay(5) # on doit laisser au moins 5ms le pin RESET a l'etat bas

wiringpi.digitalWrite(11,0) # on met le pin RESET a l'etat haut pour commencer l'utilisation de l'AFE

wiringpi.delay(5)

# Pin RDY

wiringpi.pinMode(13,0) # broche 13 en entree


# Activer le bus SPI pour la communication Raspberry <-> AFE
    
spi = spidev.SpiDev() #nouvel objet SPI (AFE)
spi.open(0,0) # sur le port SPI0 et CS (Chip Select) = 0 (correspond au pin 24, GPIO 8)
spi.max_speed_hz = 1000000 # frequence d'horloge en Hz, f = 1 MHz (Cf. datasheet AFE)
spi.mode = 0b01 #mode 1 du SPI i.e. polarite = 0, phase = 1 => mode 1 (Cf. datasheet AFE, spi timing)

## FONCTIONS  -----------------------------------------------------------

# Protocole des donnees vers les registres de l'AFE (Cf. pages 17-19 datasheet AFE):

    # Le paquet de bits a envoyer est compose de 24 bits (donc 3 octets): 
    # Le premier octet correspond a l'adresse du registre sollicite
    # Les deux octets suivants contiennent les valeurs a transmettre sur le registre 

def writeRegister(adress,data): # adress: adresse du registre dans lequel on souhaite ecrire
                                # data: donnees a transmettre dans le registre
    adress = adress & 0x1F
    
    firstByte = data >> 8 # premier octet des data
    secondByte = data & 0xFF# deuxieme octet des data
    
    spi.writebytes([adress, firstByte, secondByte])
    
# Lecture des donnees renvoyees par les registres de l'AFE (Cf. pages 17-19 datasheet AFE)

def readRegister(adress,data):
    
    adress = adress & 0x1F # derniers 5 bits de l'adresse
    adress = adress | 0x20 # permet d'etre en mode lecture (le bit 21 doit valoir 1)
    
    firstByte = data >> 8
    secondByte = data & 0xFF
    
    a=spi.xfer2([adress, firstByte, secondByte])
    print("adresse: ")
    print(a)
    print("\n")

def readData(frequence):
    
    
    # 1) Envoyer signal a une frequence donnee
    
    writeRegister(BCM_DAC_FREQ,frequence) # preparer le registre BCM_DAC_FREQ pour une mesure a une freq donnee
    wiringpi.delay(5)
    
    # 2) Mode lecture de ADC_RESULT
    
    readRegister(ADC_DATA_RESULT,0x00)

def setupAFE():
    
    # Initialisation AFE

    writeRegister(ADC_CONTROL_REGISTER1,0x5140)
    writeRegister(MISC_REGISTER1,0x0000)
    writeRegister(MISC_REGISTER2,0xFFFF)
    writeRegister(DEVICE_CONTROL1,0x6004)
    writeRegister(ISW_MUX,0x0000)
    writeRegister(VSENSE_MUX,0x0000)
    writeRegister(IQ_MODE_ENABLE,0x0000)
    writeRegister(WEIGHT_SCALE_CONTROL,0x0000)
    writeRegister(BCM_DAC_FREQ,0x0040)
    writeRegister(DEVICE_CONTROL2,0x0000)
    writeRegister(ADC_CONTROL_REGISTER2,0x0011)
    writeRegister(MISC_REGISTER3,0x0030)

    wiringpi.delay(5)

    # Initialisation des registres de BodyComposition

    writeRegister(ADC_CONTROL_REGISTER1,0x4140)
    writeRegister(MISC_REGISTER1,0x0000)
    writeRegister(MISC_REGISTER2,0xFFFF)
    writeRegister(DEVICE_CONTROL1,0x6004)
    writeRegister(ISW_MUX,0x0408)
    writeRegister(VSENSE_MUX,0x0804)
    writeRegister(IQ_MODE_ENABLE,0x0000)
    writeRegister(WEIGHT_SCALE_CONTROL,0x0000)
    writeRegister(BCM_DAC_FREQ,0x0040)
    writeRegister(DEVICE_CONTROL2,0x0000)
    writeRegister(ADC_CONTROL_REGISTER2,0x0063)
    writeRegister(MISC_REGISTER3,0x0030)

# Fin de la communication AFE/Raspberry

def endCommunication():
    spi.close()

## FONCTION PRINCIPALE -----------------------------------------------------------------------

# # Apres le reset, les registres de l'AFE sont dans leur etat par defaut, il faut donc les mettre dans leur config initiale

setupAFE()

# Lecture registres

readRegister(ADC_CONTROL_REGISTER1,0x4140)
readRegister(MISC_REGISTER1,0x0000)
readRegister(MISC_REGISTER2,0xFFFF)
readRegister(DEVICE_CONTROL1,0x6004)
readRegister(ISW_MUX,0x0408)
readRegister(VSENSE_MUX,0x0804)
readRegister(IQ_MODE_ENABLE,0x0000)
readRegister(WEIGHT_SCALE_CONTROL,0x0000)
readRegister(BCM_DAC_FREQ,0x0040)
readRegister(DEVICE_CONTROL2,0x0000)
readRegister(ADC_CONTROL_REGISTER2,0x0063)
readRegister(MISC_REGISTER3,0x0030)

# Lecture impedance

F = [0x0032, 0x0064] # liste des frequences des courants envoyes (50 kHz, 100 kHz)

for f in F:
    readData(f)

endCommunication()

And I am copying the lines of this code that are the most interesting (writing and reading registers).

def writeRegister(adress,data): # adress: adresse du registre dans lequel on souhaite ecrire
                                # data: donnees a transmettre dans le registre
    adress = adress & 0x1F
    
    firstByte = data >> 8 # premier octet des data
    secondByte = data & 0xFF# deuxieme octet des data
    
    spi.writebytes([adress, firstByte, secondByte])
    
# Lecture des donnees renvoyees par les registres de l'AFE (Cf. pages 17-19 datasheet AFE)

def readRegister(adress,data):
    
    adress = adress & 0x1F # derniers 5 bits de l'adresse
    adress = adress | 0x20 # permet d'etre en mode lecture (le bit 21 doit valoir 1)
    
    firstByte = data >> 8
    secondByte = data & 0xFF
    
    a=spi.xfer2([adress, firstByte, secondByte])
    print("adresse: ")
    print(a)
    print("\n")

def readData(frequence):
    
    
    # 1) Envoyer signal a une frequence donnee
    
    writeRegister(BCM_DAC_FREQ,frequence) # preparer le registre BCM_DAC_FREQ pour une mesure a une freq donnee
    wiringpi.delay(5)
    
    # 2) Mode lecture de ADC_RESULT
    
    readRegister(ADC_DATA_RESULT,0x00)

Could you please check if there is an error in this code?


If it's correct, it is possible that the AFE is burnt out, in this case, do you have a program and a circuit in order to check this hypothesis?

Kind regards.

Maxime

  • 0
    TI__Mastermind 49746 points

    Hello Maxime,

    Unfortunately we will not be able to review your code for correctness.

    You may first want to check if the SPI writes work. You can verify this by checking the VREF voltage.

    To verify VREF voltage (assuming device is out of reset), you will only need to write to DEVICE_CONTROL1 register address (0x09) value of 0x6006 after power-up and reset.

     

    Check the SPI timing diagram and see the timing edges conform to the datasheet description.

    For example, the device latches data on SDIN on the falling edge of SCLK. During read, data is shifted out on the SDOUT pin on the rising edge of SCLK. Also note that every time a register is read, the register must be rewritten except when reading the data output register.