CC1125: Frequency deviation setting in CC1125 RF

vikas chaudhary

Prodigy 150 points

Part Number: CC1125
Other Parts Discussed in Thread: CC1175

Hi All,
I working on CC1125 module, In which i need to configure frequency deviation,

but as per data sheet DEV_M and DEV_E need to be configure,

Now My question is "How can solve a equation with 2 unknown variables(DEV_M/DEV_E)"

whats the value of DEV_M and DEV_E for 6Khz deviation.

Kindly help me to solve this problem

over 1 year ago

0 Haiatullah Gholami over 1 year ago

TI__Expert 3220 points

Hi Vikas,

You can use SmartRF Studio to find the values for these registers. When you type in the wanted deviation in SmartRF Studio, the register values will adjust accordingly. If you want to have 6 kHz deviation, I would use DEV_E = 0x03, DEV_M = 0x3A.

Regards,

0 ZC over 1 year ago in reply to Haiatullah Gholami

TI__Genius 11950 points

To add to Haiatullah's answer (for greater understanding), from Section 5.2.1 of SWRU295 (CC112X/CC1175 Low-Power High Performance Sub-1 GHz RF Transceivers/Transmitter User’s Guide): https://www.ti.com/lit/swru295

So, the important point is that the values of DEV_M and DEV_E are the mantissa and exponent bits, respectively.

0 vikas chaudhary over 1 year ago in reply to Haiatullah Gholami

Prodigy 150 points

Thanks for reply,

I cann't use Smart RF studio, because this is user defined parameter for my project and frequency deviation will be change in RUN time so i need to calculate the values in run time.

0 vikas chaudhary over 1 year ago in reply to ZC

Prodigy 150 points

yes, My question is how to find DEV_M and DEV_E by given above equation

0 Haiatullah Gholami over 1 year ago in reply to vikas chaudhary

TI__Expert 3220 points

Hi Vikas,

There is not a straight forward way of finding these values without using SmartRF Studio. One solution could be to set DEV_M to 0. Find DEV_E value that gives the closest deviation (not higher) to the desired deviation using the Equation 1 from the user guide. Then find the DEV_M that gives the closes deviation to the desired deviation.

Regards,

0 TheGhostOf over 1 year ago in reply to Haiatullah Gholami

Mastermind 6130 points

Haiatullah: Have you checked how SmartRF Studio does this calculation?

0 vikas chaudhary over 1 year ago in reply to Haiatullah Gholami

Prodigy 150 points

well said, but if deviation isn't set exactly, its impact on RF performance

0 vikas chaudhary over 1 year ago in reply to TheGhostOf

Prodigy 150 points

No idea, how Smart RF generate these value

kindly let me know if you something about Smart Rf

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CC1125: Frequency deviation setting in CC1125 RF