Ask Hackaday: What Would You Do With The World’s Smallest Microcontroller?

It’s generally pretty easy to spot a microcontroller on a PCB. There are clues aplenty: the more-or-less central location, the nearby crystal oscillator, the maze of supporting passives, and perhaps even an obvious flash chip lurking about. The dead giveaway, though, is all those traces leading to the chip, betraying its primacy in the circuit. As all roads lead to Rome, so it often is with microcontrollers.

It looks like that may be about to change, though, based on Texas Instruments’ recent announcement of a line of incredibly small Arm-based microcontrollers. The video below shows off just how small the MSPM0 line can be, ranging from a relatively gigantic TSSOP-20 case down to an eight-pin BGA package that measures only 1.6 mm by 0.86 mm. That’s essentially the size of an 0603 SMD resistor, a tiny footprint for a 24-MHz Cortex M0+ MCU with 16-kB of flash, 1-kB of SRAM, and a 12-bit ADC. The larger packages obviously have more GPIO brought out to pins, but even the eight-pin versions support six IO lines.

Of course, it’s hard not to write about a specific product without sounding like you’re shilling for the company, but being first to market with an MCU in this size range is certainly newsworthy. We’re sure other manufacturers will follow suit soon enough, but for now, we want to know how you would go about using a microcontroller the size of a resistor. The promo video hints at TI’s target market for these or compact wearables by showing them used in earbuds, but we suspect the Hackaday community will come up with all sorts of creative and fun ways to put these to use — shoutout to [mitxela], whose habit of building impossibly small electronic jewelry might be a good use case for something like this.

There may even be some nefarious use cases for a microcontroller this small. We were skeptical of the story about “spy chips” on PC motherboards, but a microcontroller that can pass for an SMD resistor might change that equation a bit. There’s also the concept of “Oreo construction” that these chips might make a lot easier. A board with a microcontroller embedded within it could be a real security risk, but on the other hand, it could make for some very interesting applications.

What’s your take on this? Can you think of applications where something this small is enabling? Or are microcontrollers that are likely to join the dust motes at the back of your bench after a poorly timed sneeze a bridge too far? Sound off in the comments below.

58 thoughts on “Ask Hackaday: What Would You Do With The World’s Smallest Microcontroller?

    1. Probably about the same stuff I did with an Atmel 2313 almost 25 years ago, except it would be smaller and not have a resonator and have fewer external ICs and consume less power and…

      Although I do doubt my ability to put this on a PCB to do a reflow.

  1. Put it in a ring to respond to RFID as a security key. Keep your (security) keyring on an actual ring that you would normally wear, such as a wedding ring or class ring.

    I couldn’t find the power requirements info quickly from the datasheet, but you might be able to power it from skin temperature using the Seebeck effect.

    Then maybe add a sensor or two, wake up every minute and measure body temperature or oxygenation or something. An automated reader in the home would make the whole operation seamless – such as a reader embedded into a doorway that you have to pass through.

    1. From page #1: “RUN: 87µA/MHz”. Given it runs at 24MHz it would run at 2,088uA (or about 2mA) in the active state.

      What is really interesting to me is how low the low power states are. “STANDBY: 5µA with SRAM retention”. If you can store even a little bit of power, you can wake up in bursts and last a long time on very little capacity. This would pair well with energy harvesting devices.

        1. Interesting. Not trying to disagree with you but the datasheet I found only mentions the two packaging formats Adrian mentioned. Do you have a link to something showing this chip in the smaller format?

          The Ti chip seems nicer in that it’s a 32-bit ARM MCU, but I’ll grant I haven’t really worked with 8-bit since the 6502.

  2. The ADC is probably the most interesting thing to me. If they’re cheap enough, you could throw one of these at whatever you want to sample (depending on all the usual ADC considerations, of course). It looks like its I2C peripheral even has a follower mode (not always a given in MCUs), so bam, you have a bus full of serial ADCs with short analog traces, extra filtering logic, etc. One of the ADCs is also a temp sensor, which would have been extremely useful in a thermography product I worked on a few years back.

  3. I’m thinking back to one of my first design projects out of college. My employer had an existing design built around a single TTL Hex inverter IC. I was tasked with keeping the same PCB size but squeezing an MSP-430 in there and programming it to tolerate less precise pulse times and to log how many times it had been signaled in its lifetime.

    This thing would have made that trivial.

  4. Imagine a beowulf cluster of these. At $0.20, it makes sense to use it as dedicated high speed spi adc, with one module per each channel. Like a universal sensor driver with some serious protocol to communicate to main big chip. Imagine 24 of them connected to rpi2040 for eeg cap, slurping 24 channels of analog data.

    1. That’s…. not a beowulf cluster.
      That’s just device / perfrerial design structure. Commonly used these days, and yes a chip like this could be used if space was a constraint on the device side.

    1. Might be a fantastic mini-core for small fpgas like the ice40up5k. Just have a small bank of these attached that the fpga could off load small processing tasks instead of tiny softcores taking up flip-flops and bram.

    1. I was going to say I’d need a lot of them to replace all the brain I don’t use, but then I remembered I don’t have much brain to start with, so I’d only need a few to do the job.

  5. I think size by itself is pretty boring.

    The use cases shown have been done for a long time now.
    Take the earbud: The BLE still needs to be solved and there is probably dedicated hardware for noise cancelation, that can not be addressed with a 24MHz micro. Then either the BLE solution or the Audio dsp will give you a CPU for free, it’s already on one of the dies somewhere.

    If the power consumption was incredible, compared to larger devices, that would be nice, but the video did not say that.

  6. Put the µC in an optical package, along with some LEDs (R, G, B, IR) and a photo diode.
    Basically make a hackabe WS2812 that is also capable of optical communication / can act as a sensor pixel / have its own peripehrals.

  7. Wikipedia’s page on “smart dust” has a bunch of ideas, from as far back as the early 1990s. Power and wireless communication (and sufficient power for wireless communcation) are still going to be tricky, but there are some technologies to explore.

    Personally I’m hoping for a radio-controlled bumblebee. Or maybe start with a dragonfly.

    1. I think that’s alluded to in the writeup about embedding it in the board. You could put this underneath a 555 and someone looking at it would not be likely to see it.
      (“You’ll never believe what you can do with just a 555!”)

  8. I recently used spider style attiny85 to drive 10 rgb led strip for replacement lightbar for sgi octane, this would work too, but maybe not because soldering would be a nightmare. ;-)

  9. The size isn’t THAT unprecedented. NXP’s LPC1103 (32k flash, 8k RAM, 16pins, 2.17×2.32mm) came out a decade ago. Yeah, this is less than half that size, but we’re in the realm of diminishing returns WRT “new applications.” I think.

    1. 5.03mm² vs 1.38mm², thats closer to quarter of the size. .5mm vs .35mm ball pitch is somewhat significant difference. And this new TI part is also almost half the height, .35mm vs .6mm.

      That being said, .35mm pitch wlcsp is not all that exotic (MAX32660 would be better comparison point), but doing that for 8 pin chip is novel

  10. I remember TI advertising a 25 cent processor a while back. That was at 1 million quantity. I think they are doing the same saying this is a 20 cent processor you will pay 3 times that at 1000 pcs. False advertising.

  11. I worked on a product that had a 3mm wide double sided fpc and a bunch of sensors. The MCU I used was smaller than the IMU but this TI part would have made love much easier. Really small MCUs are driven by mechanical design rather than electrical

  12. I think we’re getting close to things a little smaller than a grain of rice, with induction power and an outside that’s multicolor OLED and some data flow over the induction, and capacitance touch sensor, maybe a inertial sensor that knows how it’s oriented… And then put it in transparent PLA reels with a 3D printer that has a nozzle but enough to let them flow.
    Kinda grainy prints, but you’ve now got the ability to print some very neat toys.

  13. 16k is a bit limiting but – USB encrypter?
    Place it in a small cable, plug in USB drive, data is encrypted. Key held in CPU flash.
    Need the same cable (or the key) to decrypt USB contents.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.