Jozen One
Posts: 3
Joined: Fri Oct 13, 2017 8:18 am

SPI Pins CE0 and CE1 stopped working correctly

Mon Oct 23, 2017 11:57 am

Hello,

I have used my Raspberry Pi 3 Model B to control an attenuator. Long story short, it worked but after a while the CE0 Signal stopped going from logic high to logic low and instead just remained high. I changed my python script so that the other Chip Select - the CE1 is used, but it didn't even go to high instead remained low all the time.
The other pins kept working fine (Data Signal and Clock).

To verify the problem is not on the software - side I inserted the SD-card to a second RPi same Model and it worked just fine (like it did with the other one at the beginning). I am pretty sure nobody connected a voltage to any of those pins or did anything that could cause damage to the rpi.

I just can't find out how the Rpi broke and don't want to ruin another one. Are there any tests I could run? Any ideas on how this can happen?

I connected the attenuator and the Rpi on those Pins: 3v3; GND; GND; SPI MOSI; SPI CLK; SPI CE0
and then the RPi was connected to Ethernet(RJ45) and Power.

Thanks in advance

drgeoff
Posts: 11247
Joined: Wed Jan 25, 2012 6:39 pm

Re: SPI Pins CE0 and CE1 stopped working correctly

Mon Oct 23, 2017 2:46 pm

Without details of the attenuator any replies can only be based on guesswork.
Quis custodiet ipsos custodes?

Jozen One
Posts: 3
Joined: Fri Oct 13, 2017 8:18 am

Re: SPI Pins CE0 and CE1 stopped working correctly

Tue Oct 24, 2017 8:45 am

Hello,

it's the IDT F1977 - didn't think anybody would like to read into that and actually I was hoping for some qualified guesses ;)

piras77
Posts: 147
Joined: Mon Jun 13, 2016 11:39 am

Re: SPI Pins CE0 and CE1 stopped working correctly

Tue Oct 24, 2017 10:11 am

Jozen One wrote:
Mon Oct 23, 2017 11:57 am
Are there any tests I could run?
That's quite simple: If the pin is wired, disconnect it. Switch the pin mode to output.
Set the output to High. Read the input. If the input reads Low, something is wrong.
Set the output to Low. Read the input. If the input reads High, something is wrong.
Use the tool of your choice to switch the pin mode, set output and read input.

I fried on my first Pi two pins: they always show Low now.

Here another thread rg the topic: viewtopic.php?f=44&t=63200

drgeoff
Posts: 11247
Joined: Wed Jan 25, 2012 6:39 pm

Re: SPI Pins CE0 and CE1 stopped working correctly

Tue Oct 24, 2017 10:16 am

The most common reason for the I/O pins to stop working is electrical abuse. Voltages and currents beyond the maximum allowable values. Often people interfacing RPis directly to systems with 5 volt logic level outputs. Hence the hint to provide details of what the RPi is connected to.

In your case I cannot see or guess why you have experienced these failures.
Quis custodiet ipsos custodes?

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Burngate
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Re: SPI Pins CE0 and CE1 stopped working correctly

Tue Oct 24, 2017 10:51 am

Jozen One wrote:
Tue Oct 24, 2017 8:45 am
it's the IDT F1977 - didn't think anybody would like to read into that and actually I was hoping for some qualified guesses ;)
Some of us like some bed-time reading!

On the evkit / applications circuit (page18) I notice there are 3k resistors between the serial inputs and the chip. Did you put them in?

Jozen One
Posts: 3
Joined: Fri Oct 13, 2017 8:18 am

Re: SPI Pins CE0 and CE1 stopped working correctly

Tue Oct 24, 2017 2:02 pm

Burngate wrote: Some of us like some bed-time reading!
that's awesome :!:

and yes, resistors are put in.
drgeoff wrote: The most common reason for the I/O pins to stop working is electrical abuse. Voltages and currents beyond the maximum allowable values. Often people interfacing RPis directly to systems with 5 volt logic level outputs. Hence the hint to provide details of what the RPi is connected to.

In your case I cannot see or guess why you have experienced these failures.

The Rpi only is connected to a load. The incoming MISO is not connected, so there are no 5V inputs or anything that I can imagine could hurt the Pi.

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