Review of Elecrow Pi Terminal-7”

In this article we are going to review the Pi Terminal 7 inch Display from Elecrow. The Pi Terminal is a multifunctional industrial control device based on the Raspberry Pi CM4. It comes preinstalled with Raspbian and Node-RED software and is characterized by a rich set of interface such as CAN bus, RS232/RS485, digital IO, differential input ADC, relay control, camera sockets and more.

Overview of Elecrow Pi Terminal-7”

The Pi Terminal (CrowPanel-CM4 Display) features a 7 inch IPS display with 1024×600 resolution and 5-point capacitive touch operation. The front panel is IP65 certified and dust and waterproof. The picture below shows the front of the display with Raspbian running:

Note that only the front is dust and waterproof. The back is open and provides access to a large number of interfaces. On the back and sides you find ports for CAN bus, RS232/RS485, digital I/O, GPIO, Relay, Ethernet, HDMI, USB and two camera sockets.

The backside also has connectors for LoRa, WIFI, GPS and LTE antennas. You will find the Micro SD Slot (TF Card Socket) that contains the Raspbian image on a 64G memory card on the right and the power switch for the unit is just below that.

If you remove the backplate (just 4 screws) and have a look at the inside, you can see prepared slots for a LoRaWAN Gateway Module, an SSD and a 4G Module. The LoRaWAN and the SSD share the same slot, so you can have only either of it but not both.

You can also see the Raspberry Pi CM4 module, which carries a Broadcom BCM2711 Quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz with a memory of 4GB（LPDDR4-3200 SDRAM).

The 20 pin GPIO header of the Raspberry Pi is visible in the upper right corner, just above the buzzer and the CR1220 battery for the real time clock. Attached to the backplate is a fan (not shown above) that is connected via a 4 pin socket.

For more technical details see the product description of the Elecrow Pi Terminal-7.

First Use

If you plug in the power supply and switch on the display, the system boots within about 30 seconds and then starts running the demo application, shown below:

It would have been nicer to have this demo as a separate app that does not start automatically, since typically you want to run your own application on start-up and not a demo.

To end the demo app, touch the (+) icon in the lower left corner. A pop-up menu opens and there touch the “Load Raspbebian” menu item:

For my unit the calibration of the touch screen seemed to be slightly off, since I had to touch a little bit above the (+) icon to actually get the menu to appear.

Fan Noise and Speed Control

The first thing you notice when switching on the display is the high-frequency noise of the cooling fan. In theory this fan should be temperature controlled but that is not enabled by default. To enable it, go to “Preferences” -> “Raspberry Pi Configuration”:

That will open the Configuration dialog and under the “Performance” tab you can enable the temperature control for the fan:

However, even after that, the fan still runs at high speeds and never stops, even after shutting down the system. Only by physically switching off the unit the fan can be switched off.

As it is, the loud fan noise somewhat limits the applications of the Pi Terminal-7. You definitely don’t want to install the unit in a living room, the fan noise is just too irritating.

You can, of course, unplug the fan but that reduces the load you can run on the system. Alternatively, you can implement and build your own temperature controlled cooling solution. Afterall, the GPIO pins of the Raspberry are available.

Blinking an LED

The Pi Terminal-7 comes with a Node Red Tutorial but simpler software examples, for instance, on how to use the GPIO are lacking. In this section, I therefore show you how to get started by implementing the common blink example.

GPIO port

On the right side of the Pi Terminal-7 is a GPIO port that exposes two GPIO pins (10, 22) in addition to 3.3V and ground. The port is a 4-pin JST connector and should you have one of the Elecrow CrowPanel ESP32 Displays, you can use the cable that comes with one of those.

See our CrowPanel 2.8″ ESP32 Display : Easy Setup Guide tutorial for more details. Note, however, that the pinout of the GPIO port for the CrowPanels is different from that of the Pi Terminal-7! The backplate of the Pi Terminal-7 shows the following pinout for the GPIO port:

Connecting LED to GPIO port

If you connect an LED with a resistor as shown below, then we can control it from the Raspberry Pi:

Code to blink an LED

The Pi Terminal-7 comes with two pre-installed editors Thonny and Geany. We are going to use Thonny for this example. Go to “Programming” -> “Thonny” as shown below:

and then enter the following code in the editor window:

If you press Run, the LED connected to GPIO 22 should blink with a frequency of 0.5 seconds. Here the code again, if you want to copy&paste it:

import RPi.GPIO as GPIO
from time import sleep

state = False
GPIO.setwarnings(False)
GPIO.setmode(GPIO.BCM)
GPIO.setup(22, GPIO.OUT)

while True:
   state = not state
   GPIO.output(22, GPIO.HIGH if state else GPIO.LOW)
   time.sleep(0.5)

With that you have simple example that gets you started on how to use the GPIO interface.

It would be nice, if the Pi Terminal-7 would come with software examples for each of the interfaces, e.g. how to control the Relay interface or how to use the CAN bus. But so far (Nov 2024) they are lacking.

Design and Build Quality

The overall build quality of the Pi Terminal-7 is great. The unit feels rock solid and the layout of the PCB with the two module slots is good. All the ports are easily accessible. Nice is also that all interfaces are clearly labelled on the backplate.

Note, that the power supply and also the USB ports are at the bottom of the display. Which means you cannot stand the display on the bottom, when power supply or a mouse/keyboard are connected. You will either have to mount the display on a wall or build a suitable housing.

If dust or water are an issue, you definitely need a housing since the unit is open on all sides. Only the front panel with the actual display is IP65 rated.

Software and Usability

The Pi Terminal-7 comes preinstalled with Raspbian (a free operating system based on Debian optimized for the Raspberry Pi) and Node-RED (a programming tool for wiring together hardware devices, APIs and online services). See the Node Red Tutorial for more details on how to use the latter.

Apart from that, you find some common Raspberry Pi Apps such as simple music & graphics tools and others. Most of them you will not need but the two pre-installed editors (Thonny and Geany), the shell and the browser will come in handy.

Applications and Use Cases

The main use case for the Pi Terminal-7 is definitely a Node-RED server, for instance, for home automation or to control a 3D printer farm. Due the large amount of interfaces, you can connect pretty much everything you want and the support for wireless connections (Wi-Fi, Bluetooth, LoRaWAN) is great too.

For more specialized application or battery-powered projects, let’s say a small weather station the Pi Terminal-7 is too big. You are better off with one of the smaller Elecrow CrowPanel ESP32 Displays or CrowPanel Pico 4.3″ Displays. See our Digital Clock with CrowPanel 3.5″ ESP32 Display tutorial or the Scribble on CrowPanel Pico 4.3″ Display tutorial for application examples.

Conclusion

The Pi Terminal 7 is intended as an industrial control device that supports a large number of interfaces. The display is big enough and of sufficient quality for debugging and monitoring but if you want to use it for a home automation system, you probably want a bigger display. Also due to the fan noise it is suitable for an industrial/louder environment but too noisy for home environment, e.g. living room.

On the other hand, if you are looking for a Node-RED server (that sits in your garage) with a massive amount of IO interfaces the Pi Terminal 7 is a great choice. Since it runs Raspbian on a Raspberry Pi, you will find plenty of tutorials and support should you run into problems.

Happy Tinkering and feel free to leave your comments in the comment section ; )

Links

Here some links I found useful when writing this article:

Pi Terminal-7 Product Page
Pi Terminal Wiki
7_inch_CM4_Pi_Terminal_User_Manual
Pi Terminal Node Red Tutorial