Using Iono Pi Max; Real Time Clock; Rs-232 Serial Port; Rs-485 Serial Port - Sferalabs Iono Pi Max Series User Manual

Using Iono Pi Max

Most of the features discussed in this chapter are based on features implemented on our
firmware code, version 1.0, running on the SAME54 microcontroller.
The microcontroller can be programmed with user developed custom firmware, that could
replace the factory installed version. The "Firmware upload and MCU programming"
chapter below shows how to install and configure the programming tools on Raspberry Pi
OS or other similar Linux distributions.
WARNING
The microcontroller firmware implements critical logic and checks to ensure safe and
reliable operations of Iono Pi Max including, but not limited to, fan control for heat
dissipation, the battery charger logic, the VSO regulator control, watchdog, µSD switch
matrix control, power distribution voltages, currents and interna temperature monitoring.
In order to develop a safe and reliable custom firmware, you should be fully aware of the
internal hardware architecture of Iono Pi Max, and of all safety and control requirements
needed for your application and installation constraints.

Real Time Clock

Iono Pi Max has a hardware real time clock with a dedicated long-life non-rechargeable
back-up battery.
Once the RTC module and configuration files are properly installed, you will simply use the
operating system commands to control the hardware clock.
Note that, while by default the MCP79410 RTC chip is connected to the Pi's I2C bus, it
could be re-routed, using custom firmware, to the SAME54 I2C bus (DMZ_I2C).

RS-232 serial port

Iono Pi Max uses the Raspberry Pi standard UART TX/RX pins on the GPIO connector to
implement a standard RS-232 port, without hardware flow control. This port is not
galvanically isolated. The Pi main UART is accessed as /dev/ttyAMA0 in Raspberry Pi OS.
The RS-232 port could be alternatively routed to the microcontroller and used locally by
custom firmware, or made available to the Raspberry Pi as a USB serial device (/dev/
ttyACM0).

RS-485 serial port

Iono Pi Max implements a standard RS-485 port, routed to the microcontroller and made
available to the Raspberry Pi as a USB serial device (/dev/ttyACM0).
The RS-485 port is galvanically isolated using a dedicated isolated differential line
transceiver and a high-efficiency DC-DC converter. This configuration should prevent
ground loops between devices connected through this port.
24 Iono Pi Max User Guide