In the smart home, voice agents are increasingly replacing the smartphone touchscreen interface as the primary human-machine interface (HMI). Yet, in noisier industrial and retail IoT environments, touchscreens are usually the only choice. The industrial touch-panel computer market has been in full swing for over a decade. Touch-panel systems based on Linux, and to a lesser extent, Android, are gaining share from those that use the still widely used Windows Embedded, and over the past year, several Raspberry Pi based systems have reached market. Here we look at six RPi-based contenders.
The first three models here use the stripped-down Raspberry Pi Compute Module 3 (CM3) while the last three use the full Raspberry Pi 3 Model B SBC. The CM3 gives you the same quad-core, Cortex-A53 Broadcom BCM2387 SoC as the Raspberry Pi 3, but without the real-world ports and built-in WiFi and Bluetooth. (It’s unlikely that we’ll see an RPi Compute Module based on the new Raspberry Pi 3 Model B+, which boosts the clock rate to 1.4GHz and offers faster WiFi and Ethernet, as well as Power-over-Ethernet.)
In addition to the all-in-one devices listed here, many more touchscreens are available for the Raspberry Pi 3 that could be turned toward HMI purposes. These range from the official, 7-inch Raspberry Pi Touchscreen, which competes with a variety of third-party 7-inchers, as well as 10.1-inch models like the Waveshare Raspberry Pi 10.1 inch. There are also numerous smaller screen options that are generally more suitable for home automation than industrial or retail applications.
Any RPi touchscreen add-on can be combined with a Raspberry Pi and applied to HMI use. (Here’s an Instructibles how-to on flush mounting the official RPi touchscreen on a wall.)
Purpose-built industrial touch-panel system add additional features such as wall-mounting kits and in some cases, VESA or DIN-rail mounting. Some offer extended temperature support, and one of the systems covered here includes IP65 ingress protection. Most of these systems provide industrial-friendly wide-range power supplies, and some offer opto-isolated interfaces, surge and EMC protection, and UPS.
Interfaces
Most Raspberry Pi touch-panel systems feature capacitive touch, which is generally preferred as being more precise than resistive technology. Several of the screens offer backlighting, extra-wide viewing angles, and higher contrast ratios. Many supply higher brightness (luminance) measured in candela per square meter (cd/m²), a unit which is often referred to as a nit.
The more industrially oriented systems often extend the RPi’s GPIO with various interfaces including serial, CAN, digital input and output (DIO). Other features include a watchdog timer, an IR interface, and a Real Time Clock (RTC). The new Acme CM3-Panel compensates for the CM3’s lack of onboard wireless by offering WiFi and RF radio options.
One alternative in between all-in-one touch-panel computers and a DIY system based on touchscreen add-ons is an industrial touchscreen sold without an onboard computer. For example, Industrial Shields offers a 10.1-inch resistive Industrial Aluminum EMC Panel PC that supports a bring-your-own Raspberry Pi, as well as Banana Pi and Hummingboard SBCs.
The touch panel computers
Here are some recent Raspberry Pi based touch-panel computers, with information links embedded in the titles. Most of the vendors are European (typically German), but many also have North American distributors:
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Acme CM3-Panel — This RPi CM3-based touch-panel touched down earlier this month in four wireless and I/O configurations ranging from 95 Euros ($113) to 119 Euros ($142). Standard features include a 7-inch, 800×480 touchscreen with a 90-degree viewing angle, as well a MIPI-CSI camera connector, 24x GPIO, and a wide-range 12-24V DC input. The $113 model has a USB 2.0 port while the $118 version instead provides 2.4GHz WiFi. The two higher end models offer either USB or WiFi combined with wireless modules that support Acme’s open source 868MHz Yarm RF radio module spec. The Yarm module supports Acme’s ISM 868MHz Energy Harvesting radio nodes, and there are special Yarm GPIOs in addition to the 24x GPIO array. The CM3-Panel, which is only 22mm thick, supports -20 to 70°C temperatures and ships with schematics.
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Comfile ComfilePi — Comfile’s 7-inch ComfilePi CPi-A070WR and 10.2-inch ComfilePi CPi-A102WR combine an RPi CM3 with 800 x 480, resistive touchscreens. They offer IP65 protection against ingress and support 0 to 70°C temperatures. The ComfilePi is further equipped with a 10/100 Ethernet port, 3x USB 2.0 ports, a microSD slot, and an audio jack. Serial and I2C interfaces are expressed via terminal pin connectors, and there is a 12-24V input and 5V output. Saelig sells Korea-based Comfile’s systems in North America for $226 (7-inch) and $340 (10.2-inch).
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Distec POS-Line IoT — Aimed at Point-of-Sale (PoS), HMI, and signage, Distec’s POS-Line IoT stands out with an LVDS-driven, 10.1-inch capacitive multitouch screen with 1920 x 1200 resolution. The backlit screen offers 170-degree viewing angles and 500-nit luminance. The system is a pre-assembled version of a starter kit offered for Distec’s Artista-IoT board, which incorporates a Raspberry Pi CM3 module. The Artista-IoT provides a scaler chip that enables display functions such as DICOM pre-set, gamma correction, and color calibration. The board and touch-panel both furnish RPi 3-like ports except that there are only three USB ports. Internal features include 10x GPIO, 3x UART, 2x I2C, and an I2C and USB touch sensor interface. You also get IR and OSD keypad interfaces, plus an RTC and an 8-36V or 12V power supply. U.S. customers can buy the system from Apollo Displays.
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Janz Tec emVIEW-7/RPI3 — This 7-inch, 800 x 480 capacitive multitouch touch-panel is based on Janz Tec’s emPC-A/RPI3 industrial controller, which is built around a Raspberry Pi 3 SBC. Targeted at industrial HMI applications, the emVIEW-7/RPI3 has a backlit, 350-nit screen. In addition to the exposed ports of the RPi 3, you get 8-bit DIO, a serial debug port, and an interface that supports serial and CAN. Sold in North America by Saelig for $665, the DIN-rail mountable system offers a 9-32V input and a 0 to 45°C range.</li>
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MASS RPI-07 — Like the emVIEW-7/RPI3, the RPI-07 is a 7-inch, 800 x 480 system built around a Raspberry Pi 3 SBC. The screen offers 10-finger multitouch, 250 nits, and 500:1 contrast. Most of the RPi 3’s ports are exposed, and the HDMI port is available internally and can be accessed via knockouts. There’s a GPIO connector that supports an RTC or options including DIO cards with optocouplers or analog inputs and outputs. The RPI-07 provides 12V and 24V inputs and supports flush-mounted panel PC configurations or VESA 75 arm or foot mounting. No pricing was listed.
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Sfera Labs Strato Pi Touch Display — Available directly from Italy-based Sfera Labs, the Strato Pi Touch Display comes pre-assembled with a Raspberry Pi 3 with exposed ports plus the official 7-inch Raspberry Pi Touchscreen with 800 x 680 resolution and 10-finger touch. You can pair your Pi with one of three Strato boards. The 425-Euro ($523) option gives you a Strato Pi Mini, which adds a surge-protected 9-28V terminal block input with an RTC, battery, and buzzer. The 459-Euro ($543) Base model adds to the Mini features with opto-isolated RS-232 and RS-485 interfaces, LEDs, and a watchdog. The 494-Euro ($586) UPS model adds a UPS unit based on an external lead-acid 12V battery, plus special GPIO pins and an LED dedicated to UPS. The device is protected per EN61000-6-2 (EMC) and EN60664-1 (electrical safety).
