On Friday, October 3, 2014 10:20:18 AM UTC-6, ton...@gmail.com wrote:
>
> Have you fried the chip, with an overvoltage?
>
> Em segunda-feira, 29 de setembro de 2014 05h12min08s UTC-3, Anshuman
> Rajwar escreveu:
>>
>> Hello
>>
>> I am trying to control an AD7490 16 channel ADC using spi0 on the
>> beaglebone black, currently I am using a very simple code where all I want
>> to do is get the ADC to read first channel i.e (channel 0) and return the
>> value it gets, however it seems that the only two values that AD7490
>> returns are 255 and 16. Below is the code I am using
>> #!/usr/bin/python
>>
>> from Adafruit_BBIO.SPI import SPI
>> import time
>>
>>
>>
>>
>> spi = SPI(0,0)
>> spi.msh=1000
>> spi.open(0,0)
>> spi.bpw=16
>> keepRunning=True
>> n=0
>>
>> def readVoltages(n):
>>
>> print("\n"+"talking to the ADC")
>> readings=spi.xfer([65535,65535,(2097<<4)])
>> print("output from first one"+"\n")
>> print(readings)
>> print("\n")
>> print("I am awake now")
>> print("\n")
>> readings=spi.xfer([(2097<<4)])
>> print("This is what processor gave back "+"\n")
>> print(readings)
>> print("This is what the reading is "+"\n")
>> print(readings[0]&4095)
>> print("\n")
>> adcOutput=readings[0]&4095
>> n+=1
>> return adcOutput,readings,n
>>
>>
>> while(keepRunning):
>> adcOutput, readings,n=readVoltages(n)
>> y_or_n=raw_input("Should I run again??")
>> print("\n"+y_or_n)
>> if(y_or_n is "n"):
>> keepRunning=False
>> n+=1;
>> print "I finished **********************"
>> spi.close()
>> Below is my output
>>
>> talking to the ADC
>> output from first one
>>
>> [255, 255, 16]
>>
>>
>> I am awake now
>>
>>
>> This is what processor gave back
>>
>> [16]
>> This is what the reading is
>>
>> 16
>>
>>
>> Should I run again??n
>>
>> n
>> I finished **********************
>>
>> The structure of the control register of AD7490 is below
>>
>> 11 10 9 8 7 6 5 4
>> 3 2 1 0
>> WRITE SEQ ADD3 ADD2 ADD1 ADD0 PM1 PM0 SHADOW WEAK/TRI RANGE CODING
>>
>>
>> The word size is 16 bits so when I want to program this ADC to read only
>> first channel I send
>> 2097<<4. But I always get 16, it does not matter whether I am applying
>> any voltage to the ADC or not.
>>
>> Please help me, its a very simple code and I cant think of a reason that
>> it is not working.
>>
>>
>>
>> I don't think so because all the voltages that I have applied are in
accordance with the data sheet provided by AD and the circuit provided by
them, and I noticed another thing the SPI returns last 5 bits that I send
so clearly it at least communicating. I also asked Analog Devices tech
support and they asked me to make sure that all my timings are correct I am
trying to understand how to use spidev.c to get better control of timings
but let us say what you are saying is correct how can I check if chip is
damaged
--
For more options, visit http://beagleboard.org/discuss
---
You received this message because you are subscribed to the Google Groups
"BeagleBoard" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to beagleboard+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
