Yet more SPI woes (MRF24J40MA)

Massimo Del Zotto

Hello.

I am trying to communicate to a Zigbee antenna, model as in subject.
Today I tried various settings with no avail; I have prepared my Omega2 BASE to get gcc tomorrow so I might try more accurate tests.

Various threads involving SPI issues I've seen:

For the time being, I am attempting a short read as at page 14. This seems coherent with what spi-tool ... read <--> spiTransfer would be able to do.

I tried

spi-tool -b 1 -d 32766 read 0x00

Expected: 0x00. Got: 0x00. So far so good?
Unfortunately, I always get only 0, for everything I read, for example:

spi-tool -b 1 -d 32766 read 0x2C

Expected: read of register 0x16 (PACON0) value at POR 00101001 = 0x29
Get: 0x00

I figured maybe my pins were wrong or perhaps frequency too high. So I tried

spi-tool -b 1 -d 32766 --frequency 50000 --bpw 8 --sck 7 --mosi 8 --miso 9 --cs 6 setup

Attempted other reads; this device has few non-zero fields but with no luck. I always get 0.

I need help troubleshooting this, because I have checked the connections 42 times and I'm now out of ideas. I only have a $10 multimeter. BTW, will spi-tool or the library (they are sorta equivalent from what I see) support 12-bit values? If the command-response model has to be honored, I need 12-bit values to perform long reads on this device.

Chris Stratton

@Massimo-Del-Zotto Getting nothing back often means you haven't activated the chip select that is connected to the peripheral.

A scope is really key to debugging this, or one of the cheap USB-based logic analyzers.

Massimo Del Zotto

Sounds legit.
So in the meanwhile I hooked up another RF device and re-soldered and re-checked everything again.

Nothing seemed to work either; next week I'll hook it up at a scope at office.