Voltage levels on XBEE, Pixhawk connectors and which other pins are controlled by IORef?

Q&A forumVoltage levels on XBEE, Pixhawk connectors and which other pins are controlled by IORef?
paulo asked 4 months ago

Can you please clarify the following points about the IO levels for the Ardusimple boards:
All IO pins are fixed 3,3 volts, including the TX1, RX1 on the pixhawk connector, TX2, RX2 on XBEE connector, and Timepulse,
Safeboot, Reset_N, Tx_Ready, Geofence, Extint0 (completely forgotten in the hookup guide). The erroneously named IORef pin commands only the level of the four pins RX1, TX1, RX2 and TX2 on the Arduino Rail.
That means that if the 5 Volt Arduino interfaces with the pins like Geofence, Extint0, Tx Ready, additional Level Shifters MUST be installed.
Is that the correct interpretation of that, at least for me, quite unclear documentation?

clive1 replied 4 months ago

>>The erroneously named IORef pin commands only the level of the four pins RX1, TX1, RX2 and TX2 on the Arduino Rail.
IOREF is Arduino’s own designation for THEIR bus

XBEE and PIXHAWK are inherently 3.3V signalled buses, the ZED is running at 3.3V