OCx/DIx: Open collector outputs or generic digital inputs
OC1/DI4, OC2/DI5 and OC3/DI6 can be used as open collector (OC) outputs or generic
digital inputs. They are connected to discrete open collector drivers with a maximum
output current of 100mA.
These outputs are individually protected against over-current and short circuits. When the
over-current protection is triggered, the output will open, stopping the current flow. A simple
reset to 0 of the corresponding Raspberry Pi’s GPIO pin will reset the protection.
To drive a load using an OC output, connect its positive input to the VSOUT pin and the
negative input to the OC pin.
Note that the input resistors network is permanently connected to these pins so, even
when the open collector driver is open (the corresponding Raspberry Pi’s GPIO pin is low),
a small amount of current will still be able to flow to ground through an equivalent 6.9kOhm
resistor.
When not used as open collector outputs, the OC1/DI4, OC2/DI5 and OC3/DI6 can be
used as generic digital inputs, like DI1-DI3. They are protected by a resistor network,
pulled to ground when not connected, and accept positive voltage up to the VS power
supply voltage. When used to detect the status of dry contacts, it is recommended to use
VSOUT as the voltage reference.
The DI4-DI6 front-end circuits have 2.2kOhm pull-down and 4.7kOhm series resistors.
Never apply voltage levels outside the specified operating limits to DI4, DI5 or DI6.
Voltages above the power supply voltage (VS) will permanently damage the device.
Negative voltages may also cause device malfunction or damage.
Real Time Clock
Iono Pi has an hardware real time clock with a dedicated long-life non-rechargeable back-
up battery.
The real time clock optional board is shipped with a replaceable Lithium / Manganese
Dioxide (Li/MnO2) battery installed.
The battery is only used to power the RTC chip when the main power is not available
(when the Raspberry Pi is off). Depending on operating conditions it should last up to two
years if the Iono Pi board is not powered, more if the Iono Pi receives external power.
Once the RTC modules and configuration files are properly installed, you will simply use
the date and time commands to control the hardware clock.
ATECC608A secure element
Iono Pi embeds the ATECC608A secure element chip from Microchip. The ATECC608A is
connected to the Raspberry Pi Compute Module via the I2C bus (default address: 0x60).
WARNING
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Iono Pi User Guide
