Is it possible to read a negative DC voltage from a sensor with any port of the Cyton board. I imagine A6 and A7 can't be used since the PIC32 is connected to DVDD. But is there any way to read such value while using all EEG connectors?
Another option you have is to use another microcontroller, such as an Arduino or Pi to input any analog voltage measurements, and merge with the Cyton data stream.
Note that 'voltages' are measured differentially with respect to Ground. So reversing Ground and Sensor outputs may result in a positive voltage. But again, it is not recommended to connect these directly to Cyton, since it is intended be isolated for safety reasons from external voltage sources.
If your analog DC value is powered by another (low voltage) battery or by the Cyton voltage rails, then there is no issue correcting the polarity and using the PIC32 analog inputs. Be sure your voltage falls between PIC32 limits.
Comments
Hi Opull,
It is NOT recommended to connect external voltage sources directly to the Cyton inputs. Instead use an optoisolator setup:
https://docs.openbci.com/Cyton/CytonExternal/#optoisolation
Another option you have is to use another microcontroller, such as an Arduino or Pi to input any analog voltage measurements, and merge with the Cyton data stream.
Note that 'voltages' are measured differentially with respect to Ground. So reversing Ground and Sensor outputs may result in a positive voltage. But again, it is not recommended to connect these directly to Cyton, since it is intended be isolated for safety reasons from external voltage sources.
William
If your analog DC value is powered by another (low voltage) battery or by the Cyton voltage rails, then there is no issue correcting the polarity and using the PIC32 analog inputs. Be sure your voltage falls between PIC32 limits.