I've been building a custom cape for a robotics project and one of the
chips I'm using is controlled via SPI. I've used an oscilloscope to
validate that the SPI is working as expected. However, two days ago I
noticed that the chip stopped responding and after scoping the SPI signal I
can see
No way for me to tell what you may have done, but 1.8V is not good. Any
chance you can provide more information like the pin number and connector
you are using?
What do you have connected to this pin?
How is that device powered?
Gerald
On Tue, Mar 22, 2016 at 6:47 AM, Walker Archer wrote:
> I'
Thanks for responding Gerald. The scope capture above was done with no
cape. It was taken from SPI0. The chip has one-way communication so I'm
only using SPID1 (P9_18 from memory). The clock is coming from P9_22.
Chip select is P9_17. When I get home tonight I'll try the same from SPI1
an
Forgot to add info about how the cape is powered. The chip I'm using on
the cape is an AD5206 digital potentiometer (10k). I'm using the 3.3v rail
to power the SPI side and an external 5v (4.9v measured) supply powers the
pots. However, I've been getting voltages from the pots that aren't wha
On Tue, 22 Mar 2016 05:47:19 -0700 (PDT), you wrote:
>I've been building a custom cape for a robotics project and one of the
>chips I'm using is controlled via SPI. I've used an oscilloscope to
>validate that the SPI is working as expected. However, two days ago I
>noticed that the chip stopp
Power sequencing is the key. How are you doing this?
If you are applying the 5v to the pots first you may be causing the
issue and blowing the processor pins.
All pins on the processor need to be isolated from everything until
power rails are stable.
Drive a input pin when the processor is not full
There are no other SPI chips on that bus. Since the AD5206 is permanently
a slave on the SPI bus I would think it would not try to drive the line.
On Tuesday, March 22, 2016 at 10:55:49 AM UTC-4, Harvey White wrote:
>
> On Tue, 22 Mar 2016 05:47:19 -0700 (PDT), you wrote:
>
> >I've been buildin
I suspect you're exactly right Wulf Man. I was not really paying attention
to the order I applied the power and I was assuming that the POT voltage
would be isolated from the digital control side of the chip. But I also
assumed that if I blew the drivers that I would no longer get any signal
SPI1 shows the same 1.8v output. I will attempt to move to another BBB (a
BBG actually) and if things work there then I'll assume I toasted the SPI
on this board.
On Tuesday, March 22, 2016 at 1:07:43 PM UTC-4, Walker Archer wrote:
>
> I suspect you're exactly right Wulf Man. I was not really
