Cc112x transparent mode - no output on GPIO?

When done correctly the GPIO0 pin should go up and down randomly. I could not see anything obvious, take a look at the serial example here http://www.ti.com/lit/zip/swrc253 and see if you see anything. I would recommend using synchronous serial mode and use a sync word (0xAA is sufficient) for best performance.

Do you have a CAT1 EM for CC1125? If that is the case you should at least remove the SAW filter when operating @432 MHz.

Thanks

I will use both preamble, syncword and a specific ID, but I'll enable the things as I go. I would just like to verify the direct bitstream to get started.

It's a custom hardware solution designed for the 433 MHz band :)

Just looked over the example you linked, but didn't find anything obvious.

For the final product, do you plan to you serial mode or the FIFO?

I will most likely use the supported package handling with FIFO buffers. The transparent mode just seemed like an easy way to get started and verify things.

If you are planning to use the FIFO, start by looking at the easylink example in the link I posted. To start looking at a bit stream is a step backward. If possible I would rather start by controlling the board with SmartRF Studio via a CCDebugger and confirm the board RF performance by controlling it with known software and also play with sync/ no sync, preamble length, packet length etc that way.

I will get a CCdebugger next time I need some parts anyway, seems like a great way to play with different settings.

Transparent mode might be a step back compared to FIFO, but I like to actually see the bit-stream compared to the transmitted bit-stream.

I just expected a simple problem with register settings or something like that to cause the problem.

I will take a quick look at this tomorrow in the lab.

Much appreciated, thanks a lot !

Your register settings seems to work here.

- Ensure that GPIO0 is not shorted somewhere

- Ensure that the chip status actually is Rx.

The pin will toggle when you set the required registers, if it doesn't it's likely that you are in a different state than you think you are.

Thanks a lot.

I will do some further testing and see if I can find the problem.

I did some more testing today, to find the problem.

- By increasing the RX filter bandwidth to 200 kHz, I get a constant bit-stream. Not sure why this changes anything.

- Any lower RX filter bandwidth than 200 kHz gives a ~1 ms output bit-stream, every time i strobe RX (with no carrier present)

Strobing the RX every ~250 ms. Only the short bit-stream just after the RX stobe is present..

Zooming in, it looks like only a few bits are shown before flat-lining.

If a carrier is present whle strobing RX, I'm more or less able to receive a package.

But for some reason I have to strobe RX pretty much all the time. Is there some AFC going crazy if no carrier is present? Should be possible to go into RX mode and wait for a valid carrier

After some more testing, I've found that using 432MHz everything works more or less as expected. I've tried 430 - 440 MHz with 0.1 MHz steps. No major difference in the calibration values, frequency registers set as suggested by SmartRF.

There's a noticeable difference in current-consumption, only when set to 432MHz where I get an actual output, it seems to be active and use ~20 mA,.

Setting the RX filter BW high (125 kHz+) it seems all frequencies works. Around 30kHz and with FC at 432 MHz I get an output, but it seems unstable and drops out now and then. After a while, if the antenna is touched etc. the output simply stops and current consumption clearly drops, as if the frequency lock drops out, drops out of state etc. I'm starting to think this could be hardware related

Please note that as stated in the datasheet the sensitivity is a bit poorer for multiple of the clock frequency divided by 2, in you case multiples of 16 MHz.

Thanks :)

That explains the different behavior and lost packages on 432MHz I noticed yesterday.