Course hardware

Course hardware#

reTerminal#

The reTerminal is a development board based on the Raspberry Pi Compute Module 4 (CM4) manufactured by Seeed Studio.

See reTerminal Wiki page for the complete specs and documentation

Most of the information from the following sections was scraped from [@GettingStartedReTerminal2023]

Features#

  • Integrated modular design with high stability and expandability

  • Powered by Raspberry Pi Computer Module 4 with 4GB RAM & 32GB eMMC

  • 5-Inch IPS capacitive multi-touch screen at 1280 x 720 and 293 PPI

  • Wireless connectivity with dual-band 2.4GHz/5GHz Wi-Fi and Bluetooth 5.0 BLE

  • High-speed expansion interface and rich I/O for more expandability

  • Cryptographic co-processor with secure hardware-based key storage

  • Built-in modules such as accelerometer, light sensor and RTC

  • Gigabit Ethernet Port and Dual USB 2.0 Type-A ports

  • 40-Pin header for IoT applications

Specifications#

See Specifications on the reTerminal wiki webpage.

Hardware Overview#

Chassis#

pir

Motherboard#

pir

Block Diagram#

pir

Pinout Diagram#

Please carefully pay attention to the orientation of the reTerminal inthe above diagram. The LCD and the onboard buttons are on the right sidewhereas the back of reTerminal is on the left side. Also the wholedevice is flipped upside down.

Power Supply#

The reTerminal requires a power supply that can provide a minimum of 3 Amps. The official Raspberry Pi USB-C Power Supply in included in the kit.

Compute Module 4#

The Compute Module 4 (CM4) made by the Raspberry Pi Foundation is powering the reTerminal.

Notable features:

  • Processor: Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz

See CM4 datasheet for details.

See Difference Between ARM64, ARMel, and ARMhf for more info on the different ARM architectures.

Grove Base Hat for Raspberry Pi#

In a typical Raspberry Pi, sensors would be connected via the 40-pin GPIO.

To facilitate connections of the Grove sensors, this “Hat” (term for an add-on board of the Raspberry Pi) includes the following types of connection:

  • 6 Digital

  • 4 Analog

  • 3 I2C

  • 1 PWM

  • 1 UART

See Grove base hat Wiki for details.

Sensors#

AHT20 I2C Temperature & Humidity#

See AHT20 I2C Industrial Grade Temperature & Humidity Sensor wiki for details.

  • Temperature measurement range -40 ~ 85°C, Humidity measurement range 0 ~ 100% RH.

  • Digital output, Grove I2C interface.

AHT20 Libraries#

The main module for this sensor is provided by Seeed in this Github repository and can be installed with the grove.py library.

Follow official Step by step installation for python 3 (see below). Don’t use the one-click installation or it will install to the wrong location

git clone [https://github.com/Seeed-Studio/grove.py](https://github.com/Seeed-Studio/grove.py)
cd grove.py
sudo pip3 install .

Alternatively, it’s also possible to use Adafruit’s adafruit-circuitpython-ahtx0 library to communicate with the sensor (see library’s Pypi page). However, to instantiate the provided sensor class, you will need to pass it an I2C bus instance. To instantiate an I2C bus instance, install and use the adafruit-extended-bus library (see Pypi page).

Actuators & Motors#

LED Socket#

LED in a removable socket and potentiometer for power adjustment. LED can be swapped with different colors.

See LED wiki page for details.

Cooling Fan#

5V Cooling Fan 40mm x 10mm with 2-pin JST connector.

Relay#

A digital switch. Controls the on/off flow of electricity with a small digital signal.

  • Operate voltage: 3.3V-5V

  • Input current: 100mA

  • Rated load: 5A@250VAC 5A@30VDC

See relay wiki page for details.

Cabling#

The following cables are included in the base kit:

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