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CC1120: CC1120 - Absolute minimum parts needed to transmit only at ~ 300 mhz - no receive - for smallest possible part count and footprint. Noise/intermods/outside band not an issue. Tried LNA pins to gnd. When run gets to 'C' calibrate routine it

Part Number: CC1120
Other Parts Discussed in Thread: MSP430FR6047, CC1175


CC1120 - Our first question is what is the MINIMUM circuit to only transmit at ~ 300 mhz, we don't need to receive. So the LNA input components not needed. Nor are TRX_SW associated components. (Hopefully)

We have two Dev boards, I believe the cc1120DK, and about a dozen CC1120 chips - some mounted, others waiting. We have our cpu (MSP430FR6047) only boards and our CC1120-only RF boards, separated by 1/8" as two layers, connecting SPI Bus, reset, power, gnd between them using (2) 50 mil 8 pin connectors.

Our custom MSP430Fr6047- based MCU board's spi outputs were interfaced to the existing TI cc1120-only board and programmed using the 'C' MCU program supplied by TI (but modified from the dev board's chip with minimal changes to use the MSP430Fr6047cpu I/O pins). It was then sending commands to the CC1120 TI board in the demo kit wherein there were no problems.

A configuration of our CC1120-only small board design with the LNA_N & LNA_P tied to gnd runs thru demo code ok (stepping thru debugger)  and setting registers until it gets to the calibration stage 'C' call of the TI code and then draws 500ma (!) ... where it gets too hot ( of course) and fries.

A second configuration of our board design with the LNA_N & LNA_P tied together but isolated from everything else running TI demo code software sets the first 3 registers and reads them them back OK, (one at a time) but halts on waiting for MISO line on 4th register attempt.

A Oscope reads the crystal oscillating ok.

For example, one question is - If we dont want to receive, do the differential inputs still require a DC path to gnd?

Thank you.