Have questions about FETS, transistors, measurement, power supplies, or anything else electrical?

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By RichardS
#79118 I have been following these 3 cent microcontrollers made by Padauk in Taiwan.... very cool.

They are similar to early day PIC, 1K ROM, 64 bytes RAM.... yeah really.....

These parts appear in MANY cheap chinese devices.


Whats your thoughts?

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By rudy
RichardS wrote:They are similar to early day PIC, 1K ROM, 64 bytes RAM.... yeah really.....

Way back when ... I had developed a prototype timer for a composting toilet. It had a single 7 segment led. Different letters or numbers depending on the current status. The decimal point indicated the state of the output.

A triac to turn on a 24 volt sprinkler. It had a thermistor to measure the temperature in the compost area. If the temperature got too hot due to a fire (really) the controller would turn on the sprinkler to help put it out. It had a single button for the user interface. For selecting the selected time intervals. Saved to eeprom. Short press or long press on the button would change interpretation of the input.

There was no A/D on the chip. Temperature was done by charging and discharging a cap, see how long it would take to see the digital transition. It would detect if the probe was either shorted or missing and put an error character on the 7 segment led.

It had a piezo buzzer. No crystal for the oscillator, just an RC oscillator. (prior to internal oscillators) Because the clock frequency varied, and the frequency response of the buzzer varied (not knowing where there would be peaks or dips in the sound output) I used the single 8 bit timer with a varying count in order to produce a warbling tone that would sweep a band covered by the piezo.

All of this done with the 512 location rom. (512 x 12 bits) Assembly language of course. I think it only had two levels (deep) for the stack, to calls maximum. It was one of my favorite designs. Doing so much with so little.

Richard, are these PMC150 available for purchase in small quantities?
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By lethe
rudy wrote:Richard, are these PMC150 available for purchase in small quantities?

Yes, there are available from lcsc, MOQ is 10 (of course they are a bit more expensive in low quantities).

Dave Jones (eevblog.com) has done a few videos on these chip.
However these chip, while certainly interesting, are not very appealing for hobbiest because:
  • the programmer costs 120$, you can buy a lot of ATTinys or PICs (plus a programmer) for that amount of money (STM8 or other 8051 clones are even cheaper)
  • they are one-time-programmable, so you really need the in-circuit-emulator (ICE) or be prepared to waste a lot of chips for more complicated projects
  • the ICE does not seem to be available outside of china (and will probably cost at least another 100$)
So you will need to produce at least a thousand boards to offset the intial investment in the programmer & ICE. If you just want to play around with a weird uC platform on the other hand, go nuts! :)
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By danbicks
#79121 Am I missing something here?

OTP it is like going back to the era of erasing micros using an ultraviolet light! and yes I am of that era.

Pointless post. Thank god for ESP / Microchip who now own Atmel and introduced the good old PIC16F84 the first decent flash-able market device of which I used in a multitude of designs.