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Bench Talk for Design Engineers

Bench Talk


Bench Talk for Design Engineers | The Official Blog of Mouser Electronics

Electronics’ Wizardry: An Arduino Compatible Human-Machine Interface To Win Friends And Impress People Mike Parks

Makers and engineers now have a ridiculously easy way to add a high quality touchscreen display to the Arduino UNO without a lot of fuss. It’s called the CleO35 and seems ideal for projects that need a simple yet elegant Human-Machine Interface (HMI). That’s nerd speak for the barrier between the human user and the digital device. The CleO35 was first introduced on Indiegogo, a crowdfunding site, by FTDI Chip.

FTDI Chip is a company located in Glasgow, Scotland and is perhaps best known for its very reliable “bridge technologies.” Most know FTDI’s cables with built-in microcontroller functionality; they translate communication protocols (e.g., USB-to-Serial conversion). FTDI also makes ICs and a huge range of boards (or modules, as FTDI calls them). Two new boards formally manufactured by FTDI, and now Bridgetek are rather interesting, as is the story behind them: NerO and CleO35.

NerO started with the Arduino UNO open source design, but has more power (1W) to drive accessories and CE-FCC certification for commercial use. NerO was on, also a crowdfunding site. CleO35 is a 100% hardware and software Arduino UNO compatible intelligent TFT (Thin-Film-Transistor) touchscreen display. Why did FTDI use crowdfunding sites? Were these engineering skunk-works projects that weren’t going to make it otherwise? Did FTDI’s management veto the projects? Was FTDI out of cash? I decided to find out.

I contacted FTDI’s Gordon Lunn, Customer Engineering Support Manager. In a charming but occasionally difficult to understand Scottish accent (“hub” sounded like “hup” hope?), Gordon said that FTDI used the crowdfunding sites to get exposure to, and input from, a different audience. Surveys and focus groups could not provide input on designing what people want. FTDI incorporated design ideas from invested contributors, some simple but brilliant, like locating status LEDs somewhere other than under a shield and putting higher power on the 3V3 regulator.

FTDI also listened to the desire for total Arduino hardware and software compatibility. FTDI created a CleO library that works seamlessly with the Arduino IDE, and it’s simple to program. FTDI has released the design files for the UNO-based NerO, so it’s true open source hardware. The CleO35 touch display is not fully open, however schematics are available in the User Guide.

Mystery solved. Before you start to think that FTDI made a bundle on Kickstarter, the site states that for NerO, “130 backers pledged £2,463 to help bring this project to life.” And FTDI is not ruled by an iron-fisted CEO that refused to create NerO, forcing engineers into crafty budget boosting tactics. On the contrary, the founder and CEO, Fred Dart, was involved, naming it NerO because “it’s wicked.” Actually, since most Arduino product names end in the letter “O”, Fred wanted names to follow the same tradition. Thus, you have both “CleO” and “NerO,” whose names also reflect historical Roman figures (Arduino is “Genuino” outside the U.S).

But Do We Really Need Another Arduino UNO Spin?

NerO can drive the CleO35 to full performance, driving the CleO35 on a power-hungry, all-white display without getting hot. And yes, Gordon assured me that the CleO works well with the Arduino UNO, but UNO is not able to power the Cleo touch screen display, optional CleO camera, and optional speakers all at once. UNO has difficulty refreshing if you flash the screen black then white rapidly. NerO was created for the highest-performance support of the CleO35.


Figure 1: CleO35 Bottom View


1 Speaker Out/Line In 2 Plastic Bezel
3 3.5 inch HVGA TFT I/F & Resistive Touch 4 Arduino/Genuino Configuration Jumpers
5 Arduino/Genuino I/F 6 Level Shifter
7 8MB E-Flash 8 FT903 I/O Expansion
9 MicroSD Card Socket 10 Camera Interface
11 FT903 MCU 12 USB DFU Connector
13 FT810 GPU 14 Audio Amplifier



So What Is Under The Hood Of The CleO35?

CleO35 gives you a respectable HVGA resolution (480x320) on a 3.5” TFT display, with a small form factor of 101.4mm x 73mm x 15mm. It supports both portrait and landscape orientations, and has a powerful FT903 310DMIP microcontroller so it can handle processing tasks while delivering 60 frames per second that are both anti-aliased and silky smooth. CleO35’s resistive touchscreen input capability is supported by Bridgtek's FT810 touch controller microchip. The onboard USB port can power the screen but is intended only for debugging and firmware updates. CleO35 itself is a display and touchscreen, but also provides hardware to drive audio and has an interface for a camera. It can drive an external 8ohm speaker while pumping out 1W of audio. FTDI sells a “plug-n-play” speaker module (CleO-SPK1). The same connector also lets you input audio. The device supports a mono line-in audio input so you can use an external audio source to drive it.

Figure 2: CleO-SPK1 lets us easily connect a speaker to the CleO35.

For those projects that need the photo collecting capability of a digital camera, the CleO-Camera module will deliver stunning 5MP images via the OV5640 CMOS image sensor and some flash LEDs.

Figure 3: If you need a camera for your project, the CleO-Camera module makes that a snap.

But wait, there’s more! CleO35 has a microSD card reader for a microSDHC card up to 32GB.

Lastly, the CleO-RIO is a simple yet clever little board that allows you to stack the Arduino board on top of the CleO35 (“RIO” stands for Reverse I/O adapter board). Not only has CleO provided a fantastic library for the standard Arduino IDE, but also a variety of example code to get you started. In fact when you add up the tutorials and sample projects there are over 80 Arduino sketches to help you learn how to integrate CleO with NerO.

Isn’t great it when there are standards!?

Figure 4: If you wish to use an Arduino Uno that you already have lying around, be sure to get a CleO-RIO board to make that interface simple.

One consideration before committing to a “stock” Arduino UNO board is your power budget. The LDO voltage regulator on board the Arduino UNO can source a maximum of 500mA to 1000 mA before giving up the magic smoke. That higher end limit is more theoretical than practical, and is highly dependent on the applied external voltage. While the lower end (500 mA) is enough to power the CleO35 and associated peripherals, you might hit the limit if you add additional sensors and actuators. Enter NerO.

Thanks to the open source nature of Arduino, FTDI was able to produce an Arduino derivative with a more energy efficient buck regulator that improved upon the UNO power budget. All of NerO’s design files are shared. The CleO35 has schematics provided in the user guide, but all design files are not released as of this writing. NerO provides 1A of current and comes in three varieties that only differ in pin length. If using NerO with CleO, then opt for NerO-LP1 with the longer shield pins. Shields can stack on top of and below NerO.

Figure 5: NerO is Bridgetek's Arduino-compatible dev board with a more energy efficient voltage regulator to power more devices. (Image: FTDI)

Bridgetek’s NerO and CleO35 are appealing for professionals and makers alike. There’s a CleO35 Getting Started video, and an entire site,, with all of the resources you will need to get started with CleO. NerO, being UNO compatible, uses the Arduino IDE and other UNO resources. Standard interfaces for embedded systems means that we can save a lot of time not reinventing the “HMI wheel” for every project. All together, the NerO and CleO modules are impressive, but you don’t need to tell anyone how easy it is to put together. I won’t.

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Michael Parks, P.E. is the owner of Green Shoe Garage, a custom electronics design studio and technology consultancy located in Southern Maryland. He produces the S.T.E.A.M. Power podcast to help raise public awareness of technical and scientific matters. Michael is also a licensed Professional Engineer in the state of Maryland and holds a Master’s degree in systems engineering from Johns Hopkins University.

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