CC430F5137: RX mode doesn't work at voltage lower than 2.7V

In this case you have to observe the supply voltage with a scope. When starting Rx you will have a given peak current and the question is if the CR2032 can deliver this current. It could be that you have to have large caps that could supply the peak current. Check what the supply voltage is at the moment you enter RX and see if this drops under ~1.8 V.

Thank you. But even with a power supply, it doesn't work at lower than 3.7V . I'm sure the power supply can withstand large current draw...

Thanks for your reply. I used a scope and the voltage drop of coin cell is within 0.2V, meaning the lowest output of coin cell is 2.7V. Also even with a power supply, it doesn't work with supply voltage of below 2.7V . But TX mode works, only RX mode doesn't. Is there any register in 5137 can tune the power consumption of RX mode? I looked through the family guide but didn't find any instruction on this.

Sorry, I misread the original question.

You write WOR, does that mean that this is just an issue if you use WOR and not if you go from IDLE to RX?

Thank you. I figured it out. I didn't connect the big pad on the back of the chip to ground. It's causing core voltage rise up to 2.4V, and that's why the mcu doesn't work at lower supply voltages.