SPI on Python with the Intel Galileo and tlc2543m

Question

I am doing a project that consists of 16 analog sensors, and I am acquiring its data through SPI connected to an ADC type tlc2543m, the idea is to acquire them by SPI using the Python of the Intel Galileo, that is, I am programming from the Linux of The Galileo and I communicate by ETH as if it were a server. The fact is that this is my code: but I only get strange data. I already read the datasheet of the ADC, here I leave it anyway.

How to program SPI communication from python using MRAA library???

Code:

 #This Python file uses the following encoding: utf-8
 import os, sys
 #Configure ports of SPI protocol
 import mraa
 import time
 spi=mraa.Spi(0)
 #spi.mode(mraa.SPI_MODE3)
 spi.mode(0)
 spi.frequency(20000000)
 spi.lsbmode(False)
 ss=mraa.Gpio(9)
 ss.dir(mraa.DIR_OUT)
 ss.write(1)
 sc=mraa.Gpio(8)
 sc.dir(mraa.DIR_OUT)
 sc.write(1)
 def readadc(pinaleer,ss):  
       #primera configuracion
       direccionaleer=0x0c
       resp=0x00
       segundobyte=0x00
       valordigital=0x00
       pinaleer=int(hex(pinaleer),16)
       direccionaleer = direccionaleer | (pinaleer<<4) #guardo en los primeros 4 bits la direccion a leer
       #direccionaleer = (direccionaleer<<8)
       #print hex(dieccionaleer)
       ss.write(1) #Enciendo la transferencia de datos
       resp=spi.write(bytearray(hex(direccionaleer))) #Le digo que pin quiero leer
       otra=spi.write(bytearray(0x00))#hex(direccionaleer))) #le mando ceros, ya acabé
       ss.write(0) #Apago la transferencia de datos
       time.sleep(0.0002) #Espero 20us
       ss.write(0)#Enciedo la transferencia de datos
       primerbyte=spi.write(bytearray(0x0000)) #Leo el primer byte de respuesta
       segundobyte=spi.write(bytearray(0x00)) #Leo el segundo byte, total 2Byte= 16bits de repuesta
       ss.write(1)#Apago la transferencia de datos
       salida1= (resp[3]<<8)|(resp[2])#<<4)|(resp[1])
       salida= (salida1>>4)+1
       return salida

d=0
while d<5:
#d+=1
dato1 = readadc(1,ss)
dato2 = readadc(2,ss)
dato3 = readadc(3,ss)
dato4 = readadc(4,ss)
dato5 = readadc(5,ss)
dato6 = readadc(6,ss)
dato7 = readadc(7,ss)
dato8 = readadc(8,ss)
dato9 = readadc(9,ss)
dato10= readadc(10,ss)
dato11= readadc(11,ss)
dato12= readadc(12,ss)
dato13= readadc(13,ss)
#print "Dato recibido:"
print (dato1, dato2, dato3, dato4, dato5, dato6, dato7, dato8, dato9, dato10, dato11, dato12, dato13)

TLV2543 Datasheet

Answer 1

I already made it work. Instead of using the "write" function, use the "writeByte" function, Thanks for everything !!

Anyway I leave another example of SPI communication by Python, in this case I use the IntelGalileo Gen1 and ADC type tlc2543m:

# This Python file uses the following encoding: utf-8
import os, sys
import mraa
import time

spi=mraa.Spi(0) #Bus comunication
spi.mode(mraa.SPI_MODE0) #Comunication MODE0
spi.frequency(2000000) #Frequency of 2MHz
spi.lsbmode(False) #Format data MSB
ss=mraa.Gpio(8) #wire CS
ss.dir(mraa.DIR_OUT)
ss.write(1)
def readadc(pinaleer,ss):
    dieccionaleer=0x0c #Input c=1100 so Output data length 16bits,  MSB first, Unipolar
        pinaleer=int(hex(pinaleer),16) #address bits (4)
    dieccionaleer = dieccionaleer | (pinaleer<<4) #Put address bit in the 4th bits
    #Comunication        
    ss.write(0)  #CS=0 <-- Enables the device
        esc=spi.writeByte(dieccionaleer) #First byte with input info
        esc2=spi.writeByte(0x00) #Complete the 16bits --> Clock
        ss.write(1) #CS=1 <--- Disables the device
        time.sleep(0.00020) #Wait more time than 10us= time conversion AD
        ss.write(0) #CS=0 <-- Enables the device
        primerbyte=spi.writeByte(0x00) #First byte with 8bit of information
        segundobyte=spi.writeByte(0x00) #Second byte with 4bit (MSB) information , 8+4=12bits
        ss.write(1) #CS=1 <--- Disables the device

        salida1=0x0000
        salida1=salida1 | (primerbyte << 8)
        salida1=salida1 | (segundobyte)
        salida = (salida1>>4)+1 #Output 12bits

        return salida
d=0
while d<5:
    #d+=1
    dato1 = readadc(1,ss)
    dato2 = readadc(2,ss)
    dato3 = readadc(3,ss)
    dato4 = readadc(4,ss)
    dato5 = readadc(5,ss)
    dato6 = readadc(6,ss)
    dato7 = readadc(7,ss)
    dato8 = readadc(8,ss)
    dato9 = readadc(9,ss)
    dato10= readadc(10,ss)
    dato11= readadc(11,ss) #pin Test (Vref+ - Vref-) /2    =~ 2048
    dato12= readadc(12,ss) #pin Test Vref-  0000
    dato13= readadc(13,ss) #pin Test Vref+  4096


    print (dato1, dato2, dato3, dato4, dato5, dato6, dato7, dato8, dato9, dato10, dato11, dato12, dato13)