Sjaak explores tiny, powerfull PICs

In the forum we get questions like ‘what PIC should I use’ or ‘is this the right PIC for my purpose?’. We mostly use big PICs with lots of I/O, plenty RAM, and heaps of Flash. Not because we really need them, but because we are lazy and sloppy coders.

We tend to forget about the smaller chips. Today we were surprised to see so many features crammed into the PIC 12F family of chips. There are 8 pin uCs crammed with functions like multiple timers, EUSART, PWM, Capacitive touch, ADC, DAC, onboard 1% oscillators. Best of all, many come dirt cheap, under $1 in low quantities.

We will talk about the current flagship of the 12F family: 12(L)F1822. These cute little device come in hobbyist friendly 8-pins DIP- and SOIC- or an Ian-terrifying DFN-package. The DFN is a 3x3mm flat chip that is just 0.9mm thick and can be used when space is a serious issue.

Chip Features:

  • 3.5 KB FLASH
  • 128 B RAM
  • 256 B EEPROM
  • 8 MIPS CPU Speed
  • 8 pin IC
  •  5x I/O, 1x I
  •  Enhanced Mid-range Core with 49 Instruction, 16 Stack Levels
  • Flash Program Memory with self read/write capability
  • Internal 32MHz oscillator
  • Integrated Capacitive mTouch Sensing Module
  • Data Signal Modulator Module
  • MI2C, SPI, EUSART w/auto baud
  • ECCP (Enhanced/Capture Compare PWM) Module
  • Comparator with selectable Voltage Reference
  • 4 Channel 10b ADC with Voltage Reference
  • 25mA Source/Sink current I/O
  • Two 8-bit Timers (TMR0/TMR2)
  • One 16-bit Timer (TMR1)
  • Extended Watchdog Timer (EWDT)
  • Enhanced Power-On/Off-Reset
  • Brown-Out Reset (BOR)
  • In Circuit Serial Programming (ICSP)
  • On Board In-Circuit Debug
  • Wide Operating Voltage (1.8V – 5.5V)
  • Low Power PIC12LF182x variants (1.8V – 3.6V)
  • Standby Current (PIC12LF182X): 20 nA @ 1.8V, typical
  • Active Current(PIC12LF1822): 50 uA/MHz @ 1.8V, typical
  • Mouser dropped off with 25 of these little PICs in 3x3mm DFN package, and we started right away soldering it to a test board. It was doable but it took quiet a time before our Pickit3 talked to it. We photographed the whole process and will post about it soon, but first we need a drink!

    What could you design with little baby?

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    1. Two things:

      1: I love the PIC12(L)F1822. Great little micro that works like a horse.

      2: Your RSS Feed isn’t working right now.

    2. These cute little device come in hobbyist friendly 8-pins DIP- and SOIC- or an Ian-terrifying DFN-package.

      Rofl ,

      1. Yes, the 3x3mm DFN also scares my clients – at least the ones who buy their own pick-and-place and try to learn how to operate it. The most difficult step is getting the right amount of solder paste.

    3. ian, next time you order something to digikey get a syringe of CHIPQUIK 63/37 no clean solder paste (best i’ve tried so far). It’s just about spreading a thin line of paste through all the pins (perpendicular to them) and a small blob on the centre pad, placing the chip and letting surface tension do its magic. As long as you get the paste quantity right and a uniform spread, and you respect the thermal cycle temperatures required for the paste (if you don’t it boils and apart from moving the chip, the fluxes then don’t work) you’ll get a 95% success rate with pro-looking solders. And you’ll find an extra use for your hot air gun.

      After a bit of practise, all those DFN nightmares will turn into wet dreams. Next stage, BGA’s.

      1. I think they don’t compare at all to ATTiny. PIC chips (even the bigger ones) have by fare more complex and more complete hardware peripherals than Atmel equivalent. With those PICs like the 12F1840 for example, you have even more ram, more flash, and huge number of peripherals. The only thing Atmel was doing better than Microchip was Touch Sensing, but this is over now I think, Microchip is providing such capabilities on almost all their chips architecture (even on those small DIP8 besties)

    4. Unless I get involved in FPGA, I can’t make my own computer chips so I can only look to chips like the ARM M3 Cortex as an MCU or computer-like microcontroller. Large amounts of RAM can be required if doing work to use microcontrollers to operate like a computer and the Maximite computer comes to mind.

      Thank you for this post.

    5. A year ago we had a radio treasure hunt in our university. Low power transmitters (with a range of roughly 20m) were sprinkled all over campus. The transmitters would bleep out encrypted clues which, when decoded, would give the location of the next transmitter along with a clue to its decryption key.

      I had wanted to build these when SMD soldering still seemed daunting to me. So eventually I looked away from these in favour of DIP 12F675s lying around my room.

    6. I’d probably start with designing replacement circuits for the 1st or 2nd generation auto computers. The originals were not very efficient, and they are getting hard to find. I’ve been bouncing around the idea of using these little guys for monitoring and controlling the various parts in the engine room.

    7. Once, I designed a WSN node and searched for small, no power hungry PIC. First problem is I cannot find these tiny in local market (yes, I am from third country). Next fact is that most of these chip are not easy to prototype. You need a breakout board, SMD tool etc.. Last, most developer around the net not use or promote these small (mostly use DIP package, 5V chip, like 18F84, 628, 877 etc)

      1. although these small chip are using the same core and instructions sets as 16F84,628 and others ..

        1. thanks octal. I don’t notice that.
          so, last thing (seem only for me) is no stocks in local market.
          We can do online order/purchase easily (because of sanction)

    8. I’ve had good success mounting DFN chips sideways: The lower row of pins solder easily, and the bottom pad and the top row are relatively easy to wire. You still need a steady hand and good eyes – or a microscope for us older guys!

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