I recently designed a PCB and have been testing it.The PCB mainly consists of the Bluetooth Module BMD-350 ( based on NRF52832 SOC ) and HX711.( There is an accelerometer and RGB-LED as well but we haven't mounted them yet). The schematic is attached herewith:
While testing it, I was baffled by the strange current consumption pattern of the device. We are powering the device up by a Li-Po battery 3.7V 1500mAh.And we have programmed it in such way that for 30 seconds, HX711 is active and sending weight data and BMD-350 is active and transmitting packets. For the next 30 seconds, we put the HX711 in low power mode while BMD-350 is still active and sending earlier info. Thereafter, the BLE also enters deep sleep mode.
As it is a battery powered device, we wanted to monitor current consumption and hence we connected a multimeter to the device terminals. The PCB is displaying different current consumption patterns:
Generally, every time I power it up, the device goes into either of these two states.I guess state B is the desired behavior. However, out of every 10 attempts on switching on the device, 3-4 times, it enters into state A and consumes high currents, even in sleep mode.And whats even more strange is that sometimes,when device is consuming 9.4mA in state A third mode, after 30 odd secs, it suddenly starts consuming 0.03mA. So the behavior is kind of erratic.
I de-soldered the HX711 section and the strange current pattern kind of still continued which makes me think that the problem is with BMD-350. The BMD-350 has been programmed to transmit in DC-DC Enable mode in active state and goes to deep sleep with sd_power_system_off.
Could you it be the firmware or the floating pins causing this issue ? Has anyone here faced similar problem while testing a device ? Any help will be appreciated ! Thanks.
