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Smallest/lightest FPC capable processor?

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If I wanted to do a FPC project that had:

- 2 temperature sensors (2 analog inputs)
- 5 solid state to electromechanical relay controls
- support for a simple display (Like a 2 line display) - text only

- RTC desirable
- serial i/o desirable (UART)
- battery backed store or on board flash for parameters desirable.

Processor speed not important - 5 MHz clock would be sufficient - anything higher, ok.
Floating Point not needed

What would be the slowest, cheapest processor that FPC can build code for?
(On a cheap, Arduino-like, breakout kit)


The Raspberry Pi Pico would appear to fit your needs.


--- Quote from: AlanTheBeast on August 03, 2022, 01:50:48 am ---(On a cheap, Arduino-like, breakout kit)

--- End quote ---

You mentioned it, any AVR based Arduino board: Uno, Nano. Perhaps one of the attiny based boards, but you may run out of IO pins. No build-in RTC though. FPC AVR on wiki:

Next up would be esp8266 (only one ADC channel) and esp32: - only supported in fpc 3.3.1, and a bit of hassle to link to an SDK. But you get on-chip WiFi.

Then there are plenty of ARM options, like the RP Pico.

Temperatur Sensors can have a serial interface too. Depending on the type. AVR Arduino board are state of the art and there are a lot of soloutions for external IO ,flash or flashcards. And it is cheap and you can get IO cards complete from stock.

Noted your comment about at least starting off with an Arduino-scale breakout board, but when you say "smallest/lightest" do you literally mean "small" as in some fraction of a mm2 and "light" as in mg?

In any event, even if small etc. should be interpreted as "limited memory and cheap", you are likely to find that your scale is dominated by considerations of how tolerant the MCU chip (and attached peripherals) is to varying supply voltage, whether the chip/board can supply adequate power to supply the peripherals without an external regulator and so on.

As a couple of observations that might or might not help, I've got a little RP2040 board from Waveshare programmed up as a Picoprobe. This is the size of a postage stamp, and its onboard regulator is sufficiently capable that it can drive a larger Pico breakout board with attached LEDs, SD-Card and so on.

I've also got various AVR boards where I've upgraded the loader so that it retains the cause of the last reset, which can be read via a C++ variable. However I don't know whether FPC has the capability of declaring that a (global) variable should retain its value rather than being initialised at startup.

A similar consideration applies to the RP2040: I've not yet seen anybody demonstrate how the chip's distinctive PIOs can be programmed from FPC.

I think that what I'm building up to is that while both the RP2040 and sundry AVRs (plus lots of other chips) can undoubtedly be programmed using FPC, I've got reservations as to whether it's really the right tool for the job in view of the amount of effort that the wider community has devoted to getting them working well with C++.



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