As I am currently pulling my hair out over this, I figured I'd access=20
the hive mind.

tl;dr SPI is not working, I suspect mainly because I have no clue as to=20
what I ought to be doing with resistance and capacitance. I am seeking=20
some guidance from those who've been successful

I am a hobby-ist making some LED lights for my dock, I have posted about=20
problems communicating with the NRF24L01 module previously but that was=20
mainly higher level. I am currently finding problems with the hardware=20
aspects of SPI. While I think I have the code doing what I expect I am=20
seeing some strange behaviour. The SPI is brought out to a header where=20
I connect it via 20cm of dupont wire to a breakout board so I can=20
connect my bus pirate into the circuit. As I am testing I have my 'scope=20
attached to the connector instead of the NRF (looping ground to MISO)=20
when I probe /CS, I see a nice mostly square wave from rail to rail=20
(0-5v), there is a little ripple on the switching. When I probe the=20
clock and the MOSI lines, they are not reaching the 5v rail, it seems to=20
be around 1v, and very noisy which I am assuming is causing the bus=20
pirate to multiply by 2 (ie I send 0x41, and receive 0x82) I have tried=20
the bus pirate in logic probe mode and it only detects the /CS line not=20
the clock or MOSI. It feels like these lines are open drain and need=20
pull ups, although everything I have read indicates SPI does not need=20
this.

Are there any other simple conditioning tricks I might try here? What=20
are best practices for SPI? I can post the code, the circuit, and even=20
take a picture of the 'scope trace if you'd like. This is really the=20
last part of the project before installing everything onto the dock.

Thanks for any input

Anthony
--=20
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