I have a Teensy 3.2 application that reads a sensor for 5 seconds and then hibernates (snooze library) for 2 minutes, then repeats. Since it is battery powered current consumption during snooze is a key factor. The sensor is powered off during the hibernate period by use of a MOSFET switch (Fairchild FPF2124) driven by a Teensy digital I/O pin.
The sensor is a simple serial devices that sends at 9600 baud on serial pin RX1 (it does not receive data).
With the sensor serial line disconnected from the Teensy, the system consumes 50uA in hibernate. But when the serial RX line is attached to the (powered off) sensor, current consumption goes up to 260uA. My conclusion is that there is a leakage current from the RX pin to ground through the sensor. Seems like an input pin should be high impedance and not have this kind of leakage, but maybe something changes in hibernate mode? Eventually there will be multiple sensors, so this leakage will significantly affect battery life.
I notice that digital input pins have a INPUT_DISABLE state, but not sure that can be used on pins used for serial I/O.
Any ideas how to eliminate this leakage current?
The sensor is a simple serial devices that sends at 9600 baud on serial pin RX1 (it does not receive data).
With the sensor serial line disconnected from the Teensy, the system consumes 50uA in hibernate. But when the serial RX line is attached to the (powered off) sensor, current consumption goes up to 260uA. My conclusion is that there is a leakage current from the RX pin to ground through the sensor. Seems like an input pin should be high impedance and not have this kind of leakage, but maybe something changes in hibernate mode? Eventually there will be multiple sensors, so this leakage will significantly affect battery life.
I notice that digital input pins have a INPUT_DISABLE state, but not sure that can be used on pins used for serial I/O.
Any ideas how to eliminate this leakage current?