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Hi,
we are using the CC1101 for many years now in differents products.
Right now we are evaluating the CC1310 / CC1352 Soc to expand our product's capabilities.
In my setup i have 4 devices:
1 +2): LAUNCHXL-CC1352R1 boards
3): an old ChipCon SmartRF04EB Eval Board connected to our own CC1101 based RD board.
4) one of our own handheld products, also CC1101 based
I am using SmartRF Studiov7, version 2.18.0 from July, 14 2020
a) First Test: reception of signalsfromf legacy device with CC1352: (second test and questions th this in separate post)
As a first test, i wanted to try if i could receive signals generated by our handheld device with the CC1352 Eval Board and SmartRF Studio 7.
In our system we use GSFK, 868,3 MHz, 47kHz deviation, 100kBaud data rate an 325kHz RX filter BW.
I SmartRF Studio i choose "100kbps, 2-GFSK, 50kHz deviation 868 MHz" from typical settings and adjusted Center frequency to 868,3 MHz, Deviation to 47kHz and RX Filter BW to 310.8 kHz.
We use 16bit sync word and variable packet length in our system, so i adjusted the settings in the "Packet RX" Tab accordingly (see screenshot below)
Then i put the handheld device in transmit mode (the device sends many identical packets for app 1200ms).
The reception quality was very bad - 98% packet error rate !
When i started fiddling around with the RF settings, if found that setting the Deviation from 47 kHz (which is the nominal value in our CC1101 design) to 69kHz for the CC1352, the i got much better reception:
around 2,3% Packet Error rate (see 2nd screenshot) - which is roughly what i see from our legacy design in RX mode as well.
Now my question is:
Why does the transmission not work if i set Deviation to 47kHz on both devices ? Why is the reception quality so much better, when i set the deviation to 69kHz on the CC1352 ?
I would have expected that setting the RF parameters to the same values on the CC1101 and the CC1352 would give the best results ?
Since we are still evaluating the change to CC1310 / CC1352, any help / clarification woul dbe appreciated !
thanks,
Stephan
Screenshots below:
Screenshot 1 above: Bad quality reception with CC1352 when deviation is set to same settings as CC1101 as transmitter
Screenshot 2 above: better quality reception when changing the devoiation on the CC1352R to 69kHz instead of 47kHz
- If you use SmartRF Studio on the CC1101 side, could you post a screenshot of your set-up?
- Could you measure the frequency offset between the CC1101 based boards and the CC1352R based board?
- Do you see a difference if you increase the RX BW?
- In the first screenshot it could seems like you have false sync's since it looks like 0x0406 is received as a part of the packet. I assume you are able to control this board "an old ChipCon SmartRF04EB Eval Board connected to our own CC1101 based RD board." with SmartRF Studio? If so, could you test if you manage to get error free communication using the default sync word? How many preamble bytes are you sending? Would you be able to on the CC1352R side set 3 byte sync in RX where the first byte is equal to preamble?
Hi Marie,
thanks for your reply.
Yes, i did change the BW setting from 195,9 kHz (default setting from the typical settings setup for) to 310,8 kHz since our legacy system has a RX Filter BW of 32kHz, so i wanted to start my test at around the same value.
But i think, i found the real reason for my problem; it seems not to be related to the RF settings, but to the sync word settings:
Our legacy system uses a 16bit sync word. But since the MDMCFG2.Sync_Mode is set to 3, the 16bit patteren gets repeated to form a 32bit sync word. I was not aware of this fact (it's been several years since i did the original setup). But when i looked at the legacy receiver settings i noticed the 30/32bit reception setting. That brought me onto the right track.
In my CC1352 setup i choose 16bit Sync Word Length.
If i set the sync word settings on the CC1352 to 32bit and repeat the 16bit patteren 0x0406 to 0x04060406, then the legacy system works flawlessly, with 47kHz deviation as expected. The RF BW setting is not so important (in the setup for the current test with low range and high RF levels).
Here is another screenshot with the correct settings an good reception with 47kHz deviation and 310,8 kHz RX BW:
regards, Stephan
Hi TER,
thanks for your reply. I just read your post after i resolved the issue with the sync word (see my reply to Marie). But you were right, it was a sync word issue.
Thanks,
Stephan
An issue like this is typically either related to freq offset or settings where sync word setting is on the top of the list. Good that you manage to figure it out!