CC1190 general question

1) 27 MHz is recommended for 915 MHz operation. You have to check on the board you are using which xtal frequency you are using and type this frequency in SmartRF Studio

2) Yes

3) Are you referring to pins on CC1190? Pin 2 and 5 on CC1190 should not be shorted, see the reference designs for recommended way to use it. SAW is highly recommended on this design for regulatory compliance. What is the target output power?

4) less than 1us based on the datasheet numbers

Thanks for the respond, for question 3, I just hard wire pin2 and pin5 of SAW, not CC1190, it seems working, but not sure what could be issue if doing that.

For question 4, it seems that before send STX strobe, I have to delay >1ms after set PA to 1 and LNA to 0, what could be problem?

Thanks in advance.

3) If you short pin 2 and 5 on the SAW filter you in effect disable the SAW filter. A SAW is recommended for the CC1101-CC1190 design to attenuate spurs below the carrier frequency that will otherwise violate spurious emission limits under Section 15.209 and 15.205

4) Sounds strange. What happens if you don't add the > 1 ms delay?

Hi TER,

I did more experiment these days, seems that even add delay around 10ms, the CC1190 PA is not active. I think my problem is switching CC1190 from RX to TX and back to RX.

Below are the sequence of my test:
1. initially set CC1101 in RX state(send cmd SRX), external MCU GPIO control CC1190 PA=0, LNA=1, HGM=1
2. when receiving RF packet, set CC1190 PA=1, LNA=0.
3. delay 10ms
3. Write CC1101 TX fifo data packet.
4. set CC1101 to TX,(send cmd STX)
5. Wait TX FIFO TXBEYES to 0.
6. set CC1101 in RX state, and set CC1190 PA=0, LNA=1.
I have another receiver module without CC1190, it send initial packet to (CC1101+CC1190), but it can't receive data from (CC1101+CC1190).

I found that if keep CC1190 in TX mode(PA is always 1, LNA is always 0), then it can send data packet out , other RF module can receive message from it, the only problem is the range of (CC1101+CC1190) module to receive message from other CC1101 is very short, around 20m, which is because CC1190 always in TX mode.

Any comments on it?

Thanks in advance for help.

Jason

I have just got CC1101CC1190EMK915 from TI store, hook it to my control board, and got same result. so the question is how to switch CC1190 from RX to TX mode? Is there any reference code? I am really stuck, need some help!

Thx,
Jason

I suspect that CC1190 some signals behave differently than you think.

As a test: Set a GDO equal to PA_PD and plot the MCU pins controlling CC1190 together with the PA_PD signal. The MCU signal should be high the entire time PA_PD is 0 with some margin.

Hi TER,

Thanks for the suggestion, and the issue is resolved. Actually, my problem is switch to RX too earlier after TX. I checked TX_FIFO empty to determine TX complete, which it is not correct that CRC is appended. Now by read MARCSTATE to ensure chip in RX then turn off PA. Is it the right way to verify TX complete? Any other suggestion?

Thx.