Ox: Relays; L1: On-Board Application Led; Ttl1: 1-Wire Input/Output - Sferalabs Iono Pi IPBB20R User Manual

ANALOG INPUTS EXPANSION HEADER
WARNING
Never apply voltage levels outside the specified operating limits to AI1, AI2, AI3 or AI4.

Ox: Relays

Iono Pi has four single pole single throw power relays, with normally open contacts.
The relays are driven by distinct GPIO lines on the Raspberry Pi.

L1: On-board application LED

L1 is a green on-board LED that is controlled by a GPIO lines on the Raspberry Pi.
Note that, depending on the Raspberry Pi operating system's configuration, the GPIO line
may be in a high state by default on startup, causing the LED to turn on before your
application takes control of the GPIO line.

TTL1: 1-Wire input/output

TTL1 is a bidirectional TTL I/O line (0÷5V), connected to the Raspberry Pi GPIO4 pin
through a bidirectional level shifter. It can be used as a 1-Wire bus line, but can also serve
as a generic TTL I/O or as the DATA0 line of a Wiegand interface.
The TTL1 front-end circuit has a 10.0kOhm pull-up and 470Ohm series resistors.
17 Iono Pi User Guide