EEZ Bench Box 3

by Envox

Modular, open-source test & measurement chassis

View all updates Dec 19, 2019

MicroPython Arrives on BB3

by Denis Kotlar (a.k.a. prasimix)

After much preparation and an initial proof-of-concept carried out a few months ago, we now have a functional implementation of MicroPython running on the STM32F7 MCU at the heart of BB3. Achieving this required that we modify EEZ Studio to simplify the import of MicroPython scripts and to facilitate the transfer of those scripts between your PC and your BB3. Once transferred, MicroPython scripts can be used repeatedly on the BB3 without requiring access to a PC.

MicroPython support opens up completely new possibilities for automating every day test and measurement work that requires access to a programmable power supply.

MicroPython, also know as Python for microcontrollers, is a software implementation of a programming language, largely compatible with Python 3, that is written in C and optimized to run on microcontrollers. It has become quite popular thanks to its simplicity, its code readability, its quick learning curve, and the fact that it does not require any special compilation. These qualities make it a perfect candidate for automating test and measurement procedures.

Our first demonstration of BB3’s MicroPython scripting is a simple diode tester that can be used to determine the breakdown voltage of a diode, such as a Zener diode or TVS, that is normally inversely biased. You can specify a name for the diode, via the TFT touchscreen, and it will be used to name a file on the SD card. BB3 will store the data it measures within that file. You can also set a custom voltage step, rather than using the default 100 mV, if test speed is more important than precision.

The script will use one or two DCP405 modules in the first two slots. As a result, the test voltage could be up to 80 V (with two modules coupled in series). The test current is set to 10 mA to limit max. power dissipation. When the breakdown voltage is found (i.e. when all 10 mA is drawn), script execution is stopped, and the results are displayed. Your measurements can be transferred to your PC with a single click. EEZ Studio now includes a Save as CSV option that allows you to process results using a spreadsheet application or other external software.

The example script will be included in each BB3 we ship. And more scripts are on the way. Examples might include a curve tracer, an electrolytic capacitor reformer, an automated diode tester, a battery charger, and a simple function generator. Your suggestions are welcome!

Thanks for your support, Denis

About the Author

Denis Kotlar (a.k.a. prasimix)


$154,699 raised

of $85,000 goal

181% Funded! Order Below

Product Choices


Support EEZ Studio Development

EEZ Studio is a cross-platform free and open source BB3 development environment but also attractive SCPI controller that is used to access many T&M devices using SCPI commands. Its development and support cost us money and your donation will help us to keep it alive and kicking.


BB3 - Starter (Without Peripheral Modules)

A BB3 enclosure kit without bare PCBs but with fully-assembled core modules (AUX-PS, MCU STM32F7, and BP3C DIB 3-slot backplane). The Starter provides an environment for experimenters who are willing to build their own modules or who want a specific BB3 configuration (such as a six-channel BB3).


BB3 - Two Channel (Full)

A BB3 starter kit and two full-featured DCP405 single-channel (40 V, 5 A) peripheral power modules, including an AC/DC power module for each. A two-channel programmable power source with advanced features: remote sensing, remote programming, a down-programmer, and additional OVP (with crowbar).


BB3 - Four Channel (Full)

A BB3 starter kit, two full-featured DCP405 single-channel (40 V, 5 A) peripheral power modules, and one dual-channel DCM220 peripheral power module. Includes all three necessary AC/DC modules. This is the two-channel full kit, expanded to include two additional programmable power sources.


DCP405 One Channel Module (Full)

A full-featured DCP405 single-channel (40 V, 5 A) peripheral power module with remote sensing, remote programming, a down-programmer and crowbar OVP. Includes an AC/DC module.


DCM220 Two Channel Module

A DCM220 dual-channel (2 x 20 V, 4 A) peripheral power module and its AC/DC module.


Cable Set

Two pairs of high quality, silicone, color marked (black-red), 1 m connecting cables; a pair of clip-on probes; and a pair of insulated crocodile clips.


BB3 Enclosure & Bare Boards

A BB3 enclosure kit with a wire harness, nuts and bolts for the three core modules, a 4.3" TFT touchscreen display, an encoder knob, and an 80 mm fan. Includes a set of bare PCBs for building the three core modules (AUX-PS, MCU STM32F7, and BP3C DIB 3-slot backplane) as well as PCBs for building one DCM220 two-channel peripheral power module and two single-channel peripheral power modules (either the DCP405 or the DCP405B, as they can be assembled using the same PCB). Suitable for builders with the necessary skill, time, and patience.



Envox d.o.o. is home of the Envox Experimental Zone (EEZ), an open source initiative to bridge the gap between DIY / hobbyist / educational / low-budget and professional / commercial test and measurement solutions.

Denis Kotlar (a.k.a. prasimix)

Martin Vladic

Mouser Electronics

Component Provider

TME Electronic Components

Components & Hardware Sourcing

Jedinstvo - Kartona┼ża d.o.o.


Printing & Packaging

Drives and Motors d.o.o.


PCB & PCBA Manufacturing

See Also

Subscribe to the Crowd Supply newsletter, highlighting the latest creators and projects: