[Hubert] sent us a tip about a friend’s project to rescue a laundromat from its failing electronics. We’re not entirely sure what went wrong with the old control center, but considering a replacement would have cost nearly 25,000 EUR, we think [Stefan] found the perfect solution: he gave it an Arduino and Android overhaul (translated).
Although [Stefan] explains that the boards were defective, perhaps one of our German readers can help us out with a more specific translation. More clear, however, are the steps taken to upgrade the system. The situation at the laundromat was a bit of an emergency: there was no way for customers to pay for use of the machines. As a result, [Stefan] had free reign to overhaul things as he saw fit. He decided to remove the complex button setup in favor of a touchscreen Android tablet, which provided users with a simple interface to make selections. The tablet serves only as an input device. The heavy lifting is handled by an Arduino Mega 2560, which hooks up to what remains of the original system and controls the 27 machines in the laundromat.
[Stefan] admits that he isn’t a particular fan of the Arduino, but that for the price, it’s a tough solution to beat. He’s not the only one overhauling with Arduinos. Check out some other examples of upgraded machines, like the Arduino-enhanced PopCARD vending machine.
UPDATE: [Andreas] sent in a better translation of the project page which we’ve included below. He worries his written English isn’t the best, but we think it is a lot easier to understand than the machine translation. Thank you for you work [Andreas!]
What went wrong, are the two main boards.
A new costumer called him “nothing is working! need help now!” the control center wasn’t working anymore. After opening the door, one can see some combined matrix circuits for the switches and LEDs. Shared column drivers aren’t that difficult in general, but the debugging is a little bit harder, especially in such a shared setup.
Both of those matrix boards had a malfunction, but because of the mostly easy principles it was easy enough to repair them. After some more research on the board, additional errors were found. Low glowing LEDs, LEDs without any lights, but electrically fully working, some at high resistance and others with a pure short circuit. Quite irritating because the owner affirmed that all the switches were working perfectly the other day.
After piggybacking some transistors the matrix circuit was working as expected with a simulated input, so the next step was the main board with the processor. To mention as a side note, that there was another similar main board. First one simply checks the coin-acceptor unit, serves / operates the switching matrix and operates the four identical relay cards.
Those are quite basic. Just some optoelectronic coupler driven by a clocked shifting register, mainly to switch the washing machines but also to get the finish status of the machines.
Those were kept completely unmodified in the later setup.
The next photos are about the washing machine and some boards for the washing powder dispenser.
Because he couldn’t reach some parts while being assembled, he had to dismantle the whole control center all night long, only to be sure, that the mainboards were completely broken. They have had undefined logic levels, floating signals, noting to fix here.
Instead of buying a new one for about 25.000 EUR he took a Arduino Mega2560 R3, which he doesn’t really like, but Arduinos are damn cheap, so whatever. So he added a self-made simple relay shield on a prototype board to it and was almost done.
Quite funny, but replacing all the switches and LEDs with an Android Tablet was much easier, than to keep it and connect it to the Arduino, which would have had enough ports, so he would have needed to add another one for port extension and so on. But he tried to keep it simple and replacable. In first the prototype board shied hadn’t had any semiconductors on it, but he had to add them, to get rid of some additional old boards, so he could only keep the relay cards and the two mains supply circuits.