Pimp My Microwave

Last modified on November 15, 2020

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Mechanical keyboards are the complete rage on the current time! Folks love the stress-free tactile sensation, and a few bolt on huge lengths to customize them to their loyal liking.

That begs the quiz: If we to adore it that mighty, why stop at staunch pc keyboards?

Whenever you occur to mediate about it, there are tons of on a typical basis enter units in determined want of mech-ing up!

As an illustration... a microwave keypad??

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Yep you heard that lawful!

Here is the memoir of how I added a RGB OLED sizzling-swap mechanical keypad to keep up basically essentially the most pimped-up microwave throughout the complete world!

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Click me for excessive-res video with sound!


A one yr in the past, I picked up a customary microwave for £5 at a carboot sale. It turned as soon as a "Proline Micro Chef ST44":

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It appears to be from early 2000s, and is reasonably unremarkable in each method. But it turned as soon as low-fee and it really works, so lawful ample for me!


That is, until practically precisely a one yr later. I pressed the identical outdated buttons to warmth up my meal, however nothing happened.

After the preliminary disbelief, my thorough investigation by randomly prodding buttons printed that the membrane keypad is probably going damaged. In the beginning impact a pair of buttons composed labored, however proper now the complete buttons stopped responding.

At this degree I'll fetch staunch chucked it and composed purchased my cash's worth. But it appeared like a slay staunch as a result of a low-fee plastic keypad failed. Plus I may maybe properly save a pair of kilos if I mounted it moderately then looking for a model modern one.

So I took it aside and mediate about if there turned as soon as the leisure I may maybe properly produce.


After eradicating the case, we will mediate referring to the foremost circuit board:

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  • Microcontroller at prime-center

  • Buzzer at prime-lawful

  • Blue ribbon connector for keypad at center-left

  • Transformer and retain watch over relays attain the underside

  • Complete board is thru-gap, however I wager if it really works it really works!

Here is the doorway aspect:

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The board is neatly marked, and or now not it is though-provoking to hunt it makes devour of a Vacuum Fluorescent Expose (VFD), which turned as soon as already falling out of favour by the point this turned as soon as made.

I moreover seen this board, and really each factor inside, turned as soon as designed by Daewoo, a Korean conglomerate making each factor from autos to, neatly, this.

Anyway, serve to the subject at hand. I believed I may maybe properly staunch orderly up the ribbon cable contacts and speak to it a day. Apart from I did now not mediate referring to the contacts had been manufactured from carbon(graphite?) moderately then the identical outdated metal, and I rubbed some lawful off:

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So if it wasn't damaged then, or now not it is positively damaged now. Gigantic job!

Enter the Matrix (Scanning)

Aloof, it wasn't the discontinue of the world. The keypad practically indubitably makes devour of Matrix Scanning to interface with the controller.

There would possibly maybe be an in depth introduction of this subject on Sparkfun. But briefly, matrix scanning permits us to be taught different inputs from dinky various of controller pins.

As an illustration, there are higher than 100 keys on our pc keyboard. If we merely be part of each key to an enter pin, the controller chip should fetch higher than 100 pins! This will presumably be full, delicate to route, and dear to provide.

In its impact, with a puny little little bit of cleverness throughout the firmware, we will blueprint up the buttons in a grid of columns and rows, AKA a matrix, like this:

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This form, by scanning a single row and column at a time, we will resolve which key(s) are pressed. Indubitably there are lots further technicalities, so be taught further proper right here in ship for you.

Anyway, throughout the occasion above, moderately then Four 4=16 pins, we handiest want 4 + 4=8 pins, a saving of half of! And with our pc keyboard, we are going to handiest want spherical 20 pins moderately then higher than 100!

Thus, we will mediate about that Matrix Scanning simplifies the pin rely and rating complexity of enter units.

Figuring Out the Matrix

Assist to our microwave keypad at hand. We are able to mediate about its ribbon cable is available in two elements, each with 5 pins:

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So if my assumptions are lawful, it shall be a 5x5 matrix with 25 buttons. Whenever you occur to scroll the complete method serve up, it is in all probability you'll get the keypad has 24 buttons, so it exams out!

Now we all know there are 5 columns and 5 rows, or now not it's time to resolve out which secret is which.

To produce that, I desoldered the ribbon cable connector and changed it with a straight male header:

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As a aspect current, the microcontroller is a TMP47C412AN designed by Toshiba. It's a 4-bit processor with 4KB of ROM and 128 Bytes of RAM. It will moreover directly drive Vacuum Fluorescent Tubes. So all in all, a indubitably specialised chip for residence gear. Very underpowered when in comparison with Arduinos and STM32s. But composed, it will get the job carried out!

I linked some jumper wires:

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And labeled the rows and columns with 1-5 and A-E:

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I then save the board serve, powered on, and touched each pair of wires to hunt which button it responds as.

It took a while, however lastly I came upon the matrix area of the buttons I may maybe properly per likelihood like:


So all in all, 10 numpad keys and Four retain watch over buttons. There are a bunch of diversified buttons, however I did now not hassle since I fetch now not devour them anyway.

I fast whipped up an easy schematic:

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With that, I laborious-wired some buttons on a perf board as a speedily and soiled repair:

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It indubitably works! Not now not as much as I'm going to fetch scorching meals now! And it did now not payment me a dime.

But because it's in all probability you may presumably additionally mediate about, it is very messy with 10 wires popping out of the case, and I'm certain I may maybe properly produce better.

Pimp It Up!

At some degree of the identical time, I turned as soon as engaged on duckyPad, a 15-key mechanical macropad with OLED, sizzling-swap, RGB, and delicate enter automation with duckyScript:

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Be pleased to arrange out the mission web page whilst you fetch an curiosity!

I referred to as it a "Attain-It-All Macropad", so to are dwelling as much as its establish, it turned as soon as handiest pure that I rating it engaged on my microwave too!

And if I pull this off, my lowly 20-one year-fashioned second-hand damaged microwave will rework into the handiest one throughout the complete world with mechanical switches and RGB lights! Now that is what I name ... a Korean Custom 😅.

Alternatively, it wasn't as simple because it sounds. There are a various of challenges:

  • I are looking out for to devour the prevailing duckyPad as-is, so no redesigning.

  • I are looking out for to retain it orderly and orderly, so the less wires the higher.

  • It should be powered by the microwave itself too.

PMM Board

True now, there are 10 wires popping out of the case and into my hand-made keypad, very messy.

Ideally, with duckyPad, I need it to devour handiest Three wires: Energy, Ground, and Data. With so few wires, they could maybe properly moreover be inside a single cable, which shall be mighty further orderly and orderly.

Alternatively, the microwave controller composed expects 10 wires from the keypad matrix. So which method I may maybe properly per likelihood want an adapter of some kind. Let's staunch name it PMM board.

duckyPad would search advice from PMM board, which in flip talks to the microwave controller. One factor like this:

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Not too unfriendly! Alternatively, until now now we have bought been the devour of loyal switches with the keypad matrix. But with PMM board, we should retain watch over the foremost matrix electronically to fool the microwave into considering we pressed buttons! How produce we produce it?

Blast From the Past

It got here as a puny little little bit of a shock, however after some digging, it turned out that I solved this loyal subject Three years in the past! Assist then, I turned as soon as trying to automate inputs of Nintendo Switch Joycons, they usually moreover customary matrix scanning for his or her buttons.

And the reply? Analogue Switches! You would mediate of them as long-established switches, however moderately then pushing them together with your fingers, they're managed electronically.

The chip I customary is ADG714 from Analog Units. There are Eight switches in a single chip, and they're managed by draw of easy SPI protocol:

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I fast designed the PMM board:

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It's a barely easy board. A STM32F042F6P6 is customary, and I broke out all of its pins on headers in case I may maybe properly per likelihood like them.

Since there are 14 buttons that I are looking out for to govern, two ADG714s are wished. With SPI, they could maybe properly moreover be daisy-chained with out concerns.

You would mediate about throughout the schematic that the analogue switches are wired up in staunch the identical method as my shoddy hand-soldered keypad. Apart from now they could maybe properly moreover be pressed electronically by the microcontroller.

I had the PCB made, and soldered on the complete elements:

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I did a preliminary testing with continuity beeper, and it perceived to work shapely, however we are going to handiest know evidently as soon as it is save in on the loyal factor.

Serial-ous Discuss

Now the PMM board can retain watch over the button matrix, how must composed duckyPad search advice from it?

With handiest 1 wire for info, I reckoned {that a} easy one-manner serial hyperlink must composed be higher than ample.

duckyPad would ship an easy serial message at 115200bps at any time when a secret is pressed. The PMM board receives it, and if the format is lawful, it'd maybe properly in all probability per likelihood momentarily shut the corresponding analog swap, simulating a button press to the microwave.

I added a primary-secret UARTPRINT repeat to the duckyScript parser, and created a profile for my microwave keypad.

They keys on duckyPad is organized as follows:

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Why So Detrimental?

It's all coming collectively! Which brings us to the closing quiz: How are we going to energy it?

I believed it shall be simple. There would possibly maybe be already a microcontroller on the microwave circuit board, so staunch faucet its energy and job carried out! Turns out, practically however now not fairly.

Examining the circuit board intimately, it seems the complete factor runs on antagonistic voltages.

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We are able to mediate about it will get -26V from the transformer, steps it all the most life like in all probability draw all the way down to -12V, nonetheless to -5V. The voltage regulator is a S7905PIC mounted-adverse-voltage regulator, additional confirming this concept.

I'm now harmful why it is designed this type, doubtlessly has one factor to provide with the AC transformer. Aloof, it would not indubitably subject that mighty, as or now not it is staunch from a diversified degree of reference.

I tapped two energy wires from the circuit board to energy the PMM board, and in flip, duckyPad:

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To lower confusion, I marked them 0V and -5V.

Generally, we might be part of 0V to GND, and a certain voltage to VCC. But on this case, 0V is de facto on the higher attainable. So all I wanted to provide is be part of -5V to GND, and 0V to VCC. The aptitude incompatibility consists 5V, so each factor works.

(Eagle eyed viewers would possibly maybe properly mediate about I moreover lined the buzzer with a decal. It turned as soon as so loud!)

A Duckin' Gigantic Time!

I reinstalled the circuit board, zigzag each factor up and did a speedily check out, it really works!

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You would mediate referring to the three wires going from duckyPad debug header to PMM board, apart from the 10 wires going into the retain watch over board the place the blue ribbon cable customary to be.

I linked the duckyPad to the microwave, chopped off the ends of a low-fee USB cable, and customary the Four wires inside to affix each factor up through a vent on the underside.

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Voilà! It's carried out! The first and (doubtlessly) handiest microwave throughout the complete universe with mechanical switches, OLED, and RGB lights!

Admire you ever expert the crisp and clicky tactile and audible perfection of Gateron Greens whereas heating up some frozen junk meals at 2am since you are too lazy to cook dinner dinner? Successfully, I fetch, so there would possibly maybe be that!

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Click me for excessive-res video with sound!

I need one too!

Whenever you occur to fetch an curiosity in duckyPad, it is in all probability you may presumably additionally be taught further about it and rating one proper right here😅!

And in ship for you the complete package, sadly it shall be mighty further alive to.

Every microwave fetch diversified keypad matrix layouts, so it is in all probability you may need to resolve them out, and rating and rating a PMM board your self. Not a diminutive feat, however no now not as much as the complete info is true right here! Whenever you occur to provide bolt down this course, let me know whereas it is in all probability you may presumably fetch gotten any questions!

Indubitably there are extreme voltages and attainable of microwave radiation whilst you fetch it aside, so be cautious!

Pretty tons of Stuff

I've carried out a pair of diversified stress-free initiatives over time, be happy to arrange them out:

Daytripper: Veil-my-residence home windows Laser Tripwire: Saves the day while you slack off!

exixe: Miniture Nixie Tube driver module: Remove the necessity for primary chips and multiplexing circuits.

From Aduino to STM32: An intensive tutorial to rating you started with STM32 development.

List of all my repos

Questions or Comments?

Please be happy to delivery out an trouble, query throughout the official duckyPad discord, DM me on discord dekuNukem#6998, or email correspondence dekuNukem@gmail.com for inquires.

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