The test bench for your mini-series: Discover our affordable 'maker' approach
Conventional wisdom: test benches are only for large series!
Ah, the joys of the electronics manufacturing world! However much you love the technology and your project, and are delighted to receive your shipment of cards, when you have to spend several hours flashing and testing by hand, you have to admit that it's a tedious and repetitive business.
That's when we start 💭rêver💭 automation and optimization... 🤓 a test bench 🤓!
We often think that a test bench is for large volumes, but the reality is different. In a team of makers, we like to challenge ourselves!
The daily challenge: efficiently testing components, welds and functionality.
Many of us have experienced it: that moment when you have a whole bunch of electronic boards in front of you, ready to be tested and flashed before incorporating them into the final product. It's imperative to test them thoroughly, to avoid any unpleasant surprises at the end of the process.
Why a custom test bench?
Automate and optimize your time
Manual testing steps can quickly become repetitive. If you start out telling yourself that you'll be fine, full of optimism and motivation, think about it for a second, really think about it!
Before powering the board, check for potential short circuits:
- So you have to grab the multimeter and position the probes on the test points, and the electronic board is a bit wobbly, so it's not easy.
Then, once powered up, the voltage levels are measured,
- We start up the laboratory power supply and once again come to look for the test points, hoping to read 3.3V and 12V on the multimeter.
All by hand, over and over again. It's exhausting and error-prone. Quick, get a test bench! We need to automate the whole thing!
Then program :
- Move the mouse to wake up, plug in the programmer if there's a connector, otherwise keep the programming cable pressed to the board until the program has been downloaded. And wait until you see "success" in Log. Patience ...
Finally, we check overall functionality.
- Every project is different, so it could be: plugging in the motor that the card needs to activate, checking an NFC reading, or BLE connection to a smartphone, sound broadcasting, and so on.
The magic of the "Maker" process
Let's start by analyzing this card, designed to be flashed and tested. First, let's identify the test points. Then list all the functions we can check. On this basis, we'll design the appropriate test bench.
This is also the time to evaluate technical resources and decide between what needs to be automated and what can remain the responsibility of the operator. Let's take an example: in our situation, it would have been possible to integrate a small servo-motor to activate the button to be tested. However, for budgetary reasons linked to the test bench, it's up to the operator to do this. His presence is also required to confirm that the LED lights up. If the budget had allowed, we could have developed an LED lighting detection system, using a photodiode for example. It's essential to define requirements precisely and adapt the technical solution to the budget allocated for the test bench.
The heart of the maker lies in the art of mobilizing existing resources and recombining them as one sees fit. In a bench, we can find various resources such as a Raspberry Pi, a USB barcode reader, a USB NFC reader and a Segger probe. However, there's one component that we custom-design: a PCB that houses the Pogopins. These make contact with the test points on the boards to be examined. For parts that are not available on the electronics market, we can create them using contemporary tools such as 3D printing, laser cutting or CNC.
Assembly and tuning
At BLUEGRioT, we believe that design is as much about aesthetics as it is about functionality. The BLUEGRioT test bench chassis, combining innovation and efficiency, has been designed to accommodate a variety of components, and to be modular.
Use case: test bench example
Deeper immersion: details on a test bench
After all these general explanations, let's take a look at a concrete example of a test bench.
We've put together a video to illustrate the process and the real time saved by using the test bench.
The proof is in the pictures: Video comparison Lucas Vs Mehdi
1. The protagonists: "On the left Lucas, operator taking advantage of the test bench, on the right Mehdi, operator equipped with his laboratory power supply, multimeter and computer".
2. Traceability management: "In addition to the tests to be carried out, the two operators have to manage the traceability of these tests, i.e. Lucas "beeps" a simple QR-Code like a cashier, while Mehdi has to note in a file the serial number of the card to be tested and flashed, the hardware version, and then tick "pass" or "fail" for each test carried out, to trace any potential non-conformity."
3. Risk of error: "For Mehdi, every step, every test, is an opportunity for an error, an oversight, an incorrect entry. Without a test bench, the process is not only tedious, but also exposes the project to an increased risk of error."
4. Competitive spirit vs. demonstration: "We notice that Mehdi is in a competitive spirit, striving to move quickly and efficiently. Whereas Lucas, convinced that he has won in advance, performs the 4 gestures asked of him with disconcerting slowness, in a spirit of demonstration worthy of a hare in front of a tortoise."
5. Time comparison: "Test result 1'36 for playing the test plan with the test bench, 3'46 for the operator without the test bench."
6. Optimization with the test bench: "The most striking thing is that the operator with the test bench (Lucas) has virtually nothing to do, he just breathes slowly and stares into space, so he could parallelize tasks. and why not easily work with 2 or 3 test benches to further optimize.
How much does it cost to make a custom test bench?
BLUEGRioT has built test benches for flashing and measuring, ranging from 6000€ to 60000€. It's the middle ground that's crucial here. You have to weigh the cost against the potential benefit.
If you spend €10,000 on a test bench for the production of 500 cards at €25, the investment seems unprofitable if it's based solely on saving on rejects for non-conformity.
However, it is important to consider other potential factors, such as:
- Reduced testing time and therefore labor costs.
- Improved quality perceived by customers due to fewer failures.
- The ability to use the bench to test other products or future versions.
- Reducing indirect costs linked to human error and customer returns.
That's why we insist: The test bench isn't just for mass production!
A good example is our latest production of 250 cards for the Reyouzz project!