Hi,
We are using the BLUENRG-MSQTR chip in a PCB assembly design that also has a 1.62 GHz transmitter on the board. Our PCB schematic and layout are as least as good as to what is recommended in the application notes. Particular attention was made for co-location of RF transmitters and receivers.
We have a problem.
When transmitting the 1.62 GHz RF, using an external 32.768 kHz XTAL for the low frequency oscillator on the BLUNRG chip, the chip shuts down randomly and frequently (ie: no BLE RF output, typically after several seconds. We then change to the internal RC oscillator via a register setting, the chip shuts down rarely. We also notice the application of test leads or wires etc exacerbates the symptoms. So the issue is one of RF being coupled into the BLUENRG chip.
Admittedly in lieu of not having all the microcontroller firmware up and running, we do have an external eval board with a few wires on it to control the chip’s SPI bus via connector J7 (which is normally not populated and the tracks are short). We have a suspicion the RF might be induced on one on these SPI, WAKE and ENABLE lines, but it does not explain the external vs. internal oscillator phenomena.
Does anyone have a similar experience? Or know of an issue with these chips that causes it to shut down? Any hints?
Schematic also attached.
