CC2520 EM - how to check if it's alive

I have an idea that I would like to check with you.

So now I have VDD and GND properly set but also I have connected VREG and it is high.

If I measure the voltage from DCOUPL pin on CC2520 it reads 0V. (pin #27)

My reasoning here is that VREG=1 would turn on the digital voltage regulator and thus I should read ~1.8V on DCOUPL, right?

Can I assume the cc2520 is dead if otherwise?

I also just realized that VREG=1 means VREG = 1.8V. If I change this to 3.3V, then I can read 1.8V on DCOUPL.
Any ideas?

How do you define alive?

If you only connect power to the EM that means the chip is in an undefined state since the reset line is not connected to anything.

You have to connect a SPI interface to the EM to be able to find out if it's really alive. If RBIAS=1.25 V and DCOUPL=1.8 V the important parts of the chip is on.

Alive as in "important parts of the chip are on" regardless of its current state (LPM2, 1 or active).

I didn't need to connect SPI, really.

If VDD, GND and VREG are connected the internal regulator should go on and now I understand I should be able to read DCOUPL=1.8V, right? I didn't check RBIAS, but good to know this is also a way.

In the end, my issue here was that was connecting VDD to 3.3V but my IO pins (SPI, GPIO, etc) voltage was 1.8V. The radio got "lost" and couldn't identify that VREG was high when it was 1.8V.

Both solutions worked: either 1) connect VDD to a 1.8V supply pin on my board or 2) use 3.3V IO pins instead.

This "issue", VDD and IO voltage having to be the equal, is something I could not infer from the datasheet.

thanks!

I'm not sure I can interpret this out of there. I'm looking at the cc2520 datasheet page 11, section 5.2.

The table says:

- Logic "1" input voltage:  MAX 80% of VDD. -> 0.8 * 3.3 = 2.64 V

- Logic "0" input voltage:  MIN 30% of VDD. -> 0.3 * 3.3 = 0.99  V

- Hysteresis: 0.5 V

What are you saying is that the problem is the logic "0" voltage?

If your VDD=3.3 V, 1.8 V IO gives an undefined level.

Ok, thanks, but I got that by myself since the fourth post I did on this thread.
What I'm saying now is that, in my opinion, the datasheet is not telling me that *anywhere*. Not even on section 5.2 as you proposed.

Note sure what you are asking...
I thought the question was: "This "issue", VDD and IO voltage having to be the equal, is something I could not infer from the datasheet." First, VDD and IO don't have to equal but the IO voltage has to be below VDD+0.3 V and the IO voltage has to be within the range that defines a '0'/'1'.

Yes, you are right, the question was that initially, when I didn't know about the IO voltage range.

The feedback I'm providing you now is that the table on section 5.2, which should describe the range that defines a '0'/'1', can be confusing.
I just asked 3 coworkers here to read and each of them had a different interpretation of the table at a first glance.

We believe the column names (MAX, MIN, TYP) on that table are the culprit.

In any case, the issue is now fixed and the follow-up questions are now clarified. I hope TI can consider re-working that table on newer versions of the datasheet.

Thanks for all the help!