I’m working on an RF application for a weighbridge system. The device’s role is to collect data from load cell sensors and transmit it to a receiver.

Old RF Board- CC1120+CC1190
The challenge:

• Our old RF module is no longer available, so I procured a new module that also uses CC1120 + CC1190.
• The difference is that the new RF module is designed for low-power applications, while the old one was not.
• In the new design, signals like TCXO, HGM, and VCCPA are controlled through GPIO. But our old firmware does not handle these GPIO controls.

What I did:

• Based on the attached schematic, I connected things as per my understanding.
• I designed a jumper board to fit new rf board into my old main board
• Initially, it worked for some time, but then stopped functioning. I tested multiple boards (both RF and MCU), but the issue persists.
• In the current board, the reset pin is kept high via a 4.7kΩ resistor, and I added a 6µF MLCC capacitor to provide an initial delay for oscillator stabilization.

My Question:
Did I implement the connections correctly based on this schematic? If not, what changes should I consider to make the new RF module compatible with my existing firmware?

 

If you haven't yet found a way out of this issue, I would definitely check with the supplier/manufacturer of the new module; they would know how these various interconnects operate on their own design.

At any rate, there is always a chance they simply did a copy-and-paste of the BOOSTXL-CC1120-90 design from TI - the logic of the signals and interconnects might be the same (such as the High Gain Mode - HGM).

The VCCPA is the power to the CC1190 amplifier, which can be disabled for low power applications to conserve power. If you don't care for that, simply tie this to the VCC line.

As for the external RC network for the reset pin, it will be fully dependent on how fast your TCXO will stabilize and then calculate the time constant from the RC network you created: 4.7kΩ * 6µF ~ 28ms. If too short, the device might be inoperative.

One additional aspect is that the design seems to already have a crystal on it - is this a 32kHz or the 32MHz built-in crystal. If the latter, make sure your TCXO is not clashing with the built-in crystal. That could cause hardware failures and perhaps explain why the modules worked for some time.

Good luck!