AGC_FREEZE ; freeze automatic gain control settings ?

Try the following: Read back register AGCTEST (address 0x2B) when you receive the first packet. Write AGCCTRL0.AGC_FREEZE = 3 and then write the gain setting back to AGCTEST.

thanks. i'll try that.

As a simple test, use a RF signal generator as signal source and change the power level. You will then see that AGCTEST, and hence the gain, changes for different input power levels. When you freeze the AGC gain you can manually set the gain using AGCTEST.  For a given input power level you can read the AGC gain used from register AGCTEST and if you want to keep this gain setting for the next reception you set AGC_FREEZE = 3 and then write the value you previously read from AGCTEST back into AGCTEST.

Hi Sverre. That worked! I see that I can make the AGCTEST fixed.

In order to access the AGCTEST read address I need to cast the MSB as a 1, so I should call 0xAB, not 0x2B for a read because reads always have a MSB = 1.

I tried this and it seemed promising, but when I tried to write the AGCCTRL0 address (to fix AGC_FREEZE) then I receive data intermittently (the RXFIFO gets messed up, the data takes long to acquire), which is being transmitted from another tranceiver.

But the freezing of the AGCTEST worked as you suggested. Maybe I need to rewrite AGCCTRL0 differently?

It seems as though when the AGCTEST has a low value = say 57 then the data is more intermittent, but if the AGCTEST = say 129 then the data is received quickly.

Thanks again for your help.

Quote: "Hi Sverre. That worked! I set the transceiver to receive every 5ms and print out the RSSI and gain setting.

The RSSI reading is now strange though. For example, when I print the RSSI readings most of them read about -47dBm. But about every 3rd or 4th reading of the RSSI is around -97dBm to -110dBm.

I wait to check the RSSI after 5ms delay. The RXtimout is 3ms, and I use the RC oscillator because I'm using WOR setting.

I use both the CC1100 and CC1101."

You write that the RX timeout is 3 ms and the RSSI is read after 5 ms. Is that where the problem is? What is the input power level when you read the RSSI, i.e is the TX still on and is the chip in RX mode at this time?

If the CC1100/01 is in RX mode and the difference in the RSSI readings could also be due to the SPI sync issue descibed in the CC1101 Errata Note.  

Sorry. I edited my 1st message and the way the forum works is that it emails you the first message , not the one i edited and updated.

What I was saying was that I did what you said, and it seemed promising, but when I tried to write the AGCCTRL0 address (to fix AGC_FREEZE) then I receive data intermittently (the RXFIFO stores incorrect received data and the data takes long to acquire), which is being transmitted from another tranceiver.

But the freezing of the AGCTEST worked as you suggested. Maybe I need to rewrite AGCCTRL0 differently?

It seems as though when the AGCTEST has a low value = say 57 then the data is more intermittent, but if the AGCTEST = say 129 then the data is received quickly and all the RXFIFO data is what it should be (not random garbage values).

I can just set the AGCTEST = 129 and everything will work, but i was hoping I could fix this last issue.

So you know what the AGCTEST  values can range from? Is high gain setting a larger value?

Sorry for the confusion.

AGCTEST[7:6]: First LNA gain. '00' is maximum gain, '11' is minimum gain

AGCTEST[5:3]: Second LNA gain. '000' is minimum gain, '111' is maximum gain

AGCTEST[2:0]: Digital gain. '000' is minimum gain, '111' is maximum gain

thanks. you've been really helpful!!!!