The Omzlo PiMaster is a HAT (Hardware Attached on Top) providing a gateway between the CAN bus network and a Raspberry Pi, which runs network management software for the NoCAN platform. Combine this HAT with one of more CANZERO nodes to create wired IoT applications for the home and garden.
If you don't know what NoCAN is, please check our presentation here.
The PiMaster is built around an STM32F042 ARM Cortex M0+ running at 48Mhz. This MCU communicates with the Raspberry Pi through SPI and a few additional GPIOs. It performs three main functions:
- It acts as a gateway to the NoCAN network (CAN bus).
- It controls and monitors power delivered to the network (typically 12V or 24V).
- It powers the Raspberry Pi from a voltage source from 6V to 28V.
A software application called nocand running on the Raspberry Pi uses this gateway to manage the network by performing the following tasks:
- Powering up or down the network.
- Monitoring voltage and current levels.
- Registering nodes, attributing to each one a unique address.
- Registering channels as part of the publish-subscribe protocol used in NoCAN.
- Rebooting nodes, activating their bootloader,
- Uploading or downloading firmware (hex files) to/from any node.
As a built-in safety, a smart switch controlled by the MCU will automatically switch off the power distributed to the network if there is too much current drawn (typically above 3A).
The PiMaster will work on any Raspberry Pi with a 40 pin header, including the Pi Zero.
The PiMaster HAT integrates the following components:
- The main MCU: an STM32F042.
- A CAN bus interface IC (MCP2562)
- A step-down switching regulator powering the Raspberry Pi (based on the TI TPS54202, providing up to 2A)
- A smart mosfet switch controlling power distribution to the network (an Infineon BTS5030).
- Three LEDs:
- Red: HAT power status.
- Green: Network power status.
- Yellow: Power fault indicator.
- A 4-pin pluggable 3.5mm header provides connection to the network and power (VIN, GND, CAN_L, CAN_H).
- A power DC jack used to provide 6V to 28V to the HAT.
- Debugging headers.
As shown in the picture below, the PiMaster HAT comes as:
- A fully assembled PiMaster board, except for the unsoldered 40 pin GPIO header.
- A 40 pin GPIO header to connect the PiMaster to a Raspberry-Pi.
- A 4-pin male screw terminal block.
- Two 11mm M2.5 standoffs and 4 M2.5 screws.
- A 120 ohm through-hole resistor (for optional line termination).
You can also purchase the PiMaster HAT with pre-soldered 40 pin GPIO headers for a small extra cost.
To build a NoCAN network, you will also need one or more CANZERO nodes, a Raspberry Pi, a power supply and some cables/wires. These elements are not included with the PiMaster and need to be purchased separately.