Cartft FLEETPC-ARM-300 Reference Manual page 29

Each GPI is a photo-coupled (5KVrms) digital input with schematic shown below. The
external digital input is clamped to 36V by a voltage suppressor. Refer to Appendix A for
brief specification of the photo-coupler.
GPI
(to PCF8574)
Each GPO is a photo-coupled digital output with schematic shown below. The GPO is an
output from PCF8574 I/O expander and output level is pulled-up to 5V.
GPO
(from PCF8574)
FLEETPC-ARM-300 Series
29
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external
digital
input
external
digital
output