Auxiliary Voltage Outputs; Hardware Watchdog - Sferalabs Iono Pi Max v2 3+ Lite User Manual

Starting from a power off condition, Iono Pi Max will not power-up if only the back-up
battery is connected.
Battery voltage and charge current can be monitored reading files ups/charger_mon_v, in
mV (I2C control register 147), and ups/charger_mon_i, in mA (I2C control register 148).
Note that, when Iono Pi Max is being powered by the UPS battery, ups/charger_mon_v
continues to show the battery voltage, while ups/charger_mon_i returns a value close to
zero.

Auxiliary voltage outputs

Iono Pi Max has an auxiliary regulated voltage output, labeled VSO on the terminal block,
that can be set in a 12Vdc to 24Vdc voltage range, and is powered by the UPS.
In the factory default configuration, VSO is enabled, and set for 12V output voltage.
VSO can be enabled/disabled writing 1 or 0 to the power_out/vso_enabled sysfs file (I2C
control register 132).
The output voltage, from 11.5V to 24.5V, is set writing the voltage in mV to power_out/vso
(I2C control register 133).
The read-only sys_state/vso_prot (I2C control register 140) file returns 0 in normal
conditions, or 1 if the VSO output is in over-current protection, with the output temporarily
disabled.
The read-only sys_state/vso_err (I2C control register 140) file returns 0 in normal
conditions, or 1 if the Iono Pi Max controller is unable to control the voltage regulator
setting. This should never happen, and most likely indicates a hardware failure. The
controller automatically disables the VSO output if this error occurs.
Iono Pi Max also has an auxiliary 5Vdc voltage output pin on the terminal block, labeled
5VO, to supply power to external 5V loads, like 1-Wire devices. The current output limit is
500mA. An internal protection circuit shuts down the 5VO line if the current limit is
exceeded.
In the factory default configuration, 5VO is enabled.
5VO can be enabled/disabled writing 1 or 0 to the power_out/5vo_enabled sysfs file (I2C
control register 137).
The read-only sys_state/5vo_prot (I2C control register 140) file returns 0 in normal
conditions, and 1 if the 5VO output is in over-current protection, with the output temporarily
disabled.

Hardware watchdog

Iono Pi Max implements a dedicated hardware watchdog circuit that can be used to
perform a power cycle of the Raspberry Pi Compute Module.
Being controlled by Raspberry Pi's GPIO pins, it is extremely easy to control watchdog
operation using simple custom scripts in your application.
The watchdog can also swap the boot SD card after one or more consecutive watchdog
timeouts, to automatically recover from SD cards failures.
36 Iono Pi Max User Guide