ExtRaPi: Raspberry Pi HAT with power supply, RS485, RS232 and 1-Wire bus

You can bring your Raspberry Pi to perfection with ExtRaPi! The popular Raspberry Pi will get an industrial extension: a high-quality power supply with an input range of up to 30 V, a galvanically isolated RS485 bus, a RS232 serial port with TTL levels, a touch screen interface, real time clock (RTC) with a battery backup, a 1-Wire bus for a thermometer or iButton reader, SPI, I2C and even a watchdog.

Features of the expansion board for the Raspberry Pi

• Electronics designed for reliable industrial use in automation.
• Quality power supply with a range of 9 to 30 V DC and an output of up to 5 A for the Raspberry Pi. (The need to power the Raspberry via the USB connector is eliminated.)
• Power supply connection with high-quality industrial push-in terminal.
• RS232 serial port (RxD, TxD, GND).
• RS232 serial port with TTL levels.
• Galvanically isolated RS485 industrial bus with push-in terminal.
• Battery backed up real time clock (DS1307).
• DSI interface and I2C connector for standard 7" Raspberry Pi Touch Display. ExtRaPi has enough power to power the display.
• Smart WatchDog for automatic restart of Raspberry Pi in case of problems.
• 1-Wire interface for connecting a Dallas iButton thermometer or chip reader.
• SPI and I2C interfaces connected to connectors for easy connection of other peripherals.
• Compatible with Raspberry Pi 2B, 3B, 3B+ and 3A+ and 4B.
• Tip: With ExtRaPi, you can easily run the Node-RED automation system on your Raspberry Pi and measure the temperature e.g. with our TQS4

Peripherals

Raspberry Pi Industrial Extension Peripherals

Power supply for Raspberry Pi

• Finally, a quality power supply with sufficient power for the entire Raspberry and a 7" display!
• Input range: 9 to 30 V DC
• Output load: 5 A (available for Raspberry Pi and USB peripherals)
• Reverse polarity protection: yes
• Wire connection: Spring terminal for stranded and solid wire 0.2 to 1.5 mm²

RS485 industrial bus for Raspberry Pi

• Universal bus for connecting up to 32 other devices. For example, our TQS4 thermometers, THCO2 (CO2, temperature, humidity), THT2 (temperature, humidity) sensors, Quido I/O modules, etc.
• Galvanic separation: yes, inductive.
• Wire connection: Spring terminal for stranded and solid wire 0.2 to 1.5 mm²
• GPIO used on RPi: 14, 15
• The BIAS jumpers can be used to connect 680 Ω resistors defining the quietness of the line.
• A 120 Ω resistor can be connected via the TERM jumper if the RPi is an RS485 bus terminal.
• The port is merged with RS232 TTL and RS232. Common indication by RxD and TxD indicators.
• Modbus library for Node-RED: For example node-red-contrib-modbus.

RS232 serial port for Raspberry Pi

• Ideal for peripherals such as contactless readers, industrial PLCs, etc.
• Voltage levels: V.24 (standard)
• RS232 signals: RxD, TxD, GND
• Connector type: S3B-PH-K-S
• GPIO used on RPi: 14, 15
• The port is merged with RS232 TTL and RS485. Indication by RxD and TxD indicators.

RS232 TTL serial port for Raspberry Pi

• Voltage levels: TTL 5V
• RS232 signals: RxD, TxD, GND
• Connector type: S3B-PH-K-S
• GPIO used on RPi: 14, 15
• The port is merged with RS232 TTL and RS485. Indication by RxD and TxD indicators.

1-Wire bus for Raspberry Pi

• Designed for connecting DS18B20 thermometers, iButton chip readers (for attendance system), etc.
• Voltage levels: 5V
• Max. pin current +5V: approx. 15 mA
• Connector type: JST PH
• GPIO used on RPi: 4
• With port damage protection on Raspberry Pi.
• Node-RED library: For example node-red-contrib-ds18b20-sensor.

Real time clock (RTC) with backup for Raspberry Pi

• The circuit retains the current system time even in the event of a main power failure.
• RTC circuit used: DS1307 on the I2C bus
• Backup battery: CR2032
• GPIO used on RPi: 2, 3 (SDA, SCL)
• This library can be used for Raspbian Stretch and Buster (now Raspberry Pi OS).

Dynamic Watch dog for Raspberry Pi

• The watch dog can check if Raspberry Pi is stuck due to an program anomaly or elsewhere. If the GPIO24 status does not change regularly from 1 to 0, ExtRaPi resets the Raspberry via the designated pins and Raspberry Pi is being restarted.
• How does it work?
  1. Immediately after power connection the timer set to 3 minutes starts running.
  2. If no change is recorded on GPIO24 from 1 to 0 during this time, Raspberry Pi will be restarted.
  3. Raspberry is held in reset for 9 sec.
  4. If a reset has occurred, the timer is doubled, i.e. to 6, 12, 24, etc. minutes. It gives RPi more time to start correctly next time.
  5. If the GPIO24 changes regularly from 1 to 0, the timer is reset to a new 3 minute countdown.

SPI bus

• Universal serial bus for connecting other peripherals.
• Connector type: S8B-PH-K-S
• Used GPIO: 7, 8, 9, 10, 11 (CE1, CE0, MISO, MOSI, SCLK)
• 5 V (ExtRaPi source) and 3.3 V (RPi source, pin 1) are also connected to the SPI bus connector.

I2C bus - 7" touch screen for Raspberry Pi

• Universal serial bus for connecting other peripherals.
• The connector exactly matches the power and communication connector of the 7" Raspberry Pi Touch Display.
• Used GPIO: 2, 3 (SDA, SCL)
• A 5 V power supply (ExtRaPi source) is also connected to the I2C bus connector.
• Connector type: pin strip 5 x 2.54 mm

Other technical parameters

• Mounting holes: 3 mm diameter for mounting directly on the Raspberry Pi.
• Package Content:
  1. ExtRaPi
  2. Columns and screws for mounting on Raspberry Pi
  3. CR2032 battery