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SPI bus noise while WiFi communications are active

PostPosted: Tue Aug 04, 2015 2:32 pm
by grtyvr
I have a project where I have two AS5048A angular position sensors connected to an ESP8266-12 using SPI (GPIO 12, 13, 15 and 15) plus GPIO 04 as the SS pin for the second sensor. When there is no WiFi activity the sensors return stable readings, but when WiFi is active I get a lot of jitter. Any suggestions as to what i should try in order to resolve this? I have 5v power heading into an LM317 regulator for a 3.3v supply to the circuit.

Thanks for any leads!

Re: SPI bus noise while WiFi communications are active

PostPosted: Tue Aug 04, 2015 8:32 pm
by grtyvr
I think it is the power supply circuit based on the lm317. When I hook it up to a bench supply at 3.3 the jitter goes away. So I will add some filtering to the 317 supply to see if I can make it a bit more stable.

Re: SPI bus noise while WiFi communications are active

PostPosted: Tue Aug 04, 2015 9:04 pm
by grtyvr
Yes. I added a 1uF capacitor to the output pin and now the jitter is gone.