[chbot] Help track down a processor - the double chox fish challenge
markaren1 at xtra.co.nz
Thu Jun 24 09:13:30 BST 2021
Thanks, Stephen, Charles, Everyone.
Current plan is to just make a new board with a '328; more than enough
CPU horse-power, and a well understood architecture.
On 24/06/2021 6:47 PM, Stephen Irons wrote:
> Padauk PFS173-S20 is a SOIC-20 and has power on 6 and ground on 15 --
> the opposite of yours -- and pins 12 and 13 can be an analog input to a
> comparator with an adjustable reference.
> Perhaps some of their other series have a different pinout. See
> In case you are attracted to 'the 3c microcontroller'
> * C-like language, but really just assembler with some C syntax for
> loops and conditionals, etc.
> * No stand-alone command-line compiler, so cannot automate building, etc.
> * Home-grown IDE with all of the disadvantages of a home-grown IDE.
> * Windows only tools.
> * Inaccurate in-circuit emulator. At least they do provide one, but it
> has significant differences from the real parts. Also, it only works
> with the low-grade debugger in the home-grown IDE.
> * Buggy datasheets. They do have errata, but you have to look for
> them. I see that they now have one dated 2020-06, so perhaps that
> problem has gone away.
> * In-circuit programming needs dedicated pins or careful thought as it
> needs high voltages.
> It has an analog comparator, timers and PWM generators, but no other
> peripherals (UART, SPI, I2C, etc). I implemented a bit-banged I2C slave
> on a PFS173-S8 (SOIC-8).
> I would not use them again, unless a cost-benefit analysis showed that
> it would be an advantage. You would need significant quantities to
> offset the cost of learning the ins and outs of new tools, new
> archtecture, etc. Our client was hooked by the '3c' bit, and bought all
> of the (really cheap) tools, but failed to appreciate how expensive 3
> weeks of debugging might be, to find and fix a race condition that
> happens once per hour on the torture test jig, and to radically modify
> the software when one of the external time-constants turned out to be
> too long for the 8-bit timer, and to find out that there was no reliable
> way to increment on counter overflow and not miss I2C events, and so on.
> I would use an STM32 or similar for a dollar or two, and get the
> hardware to do stuff that hardware is good at.
> Stephen Irons
> On Wed, Jun 23, 2021 at 13:10, Mark Atherton <markaren1 at xtra.co.nz> wrote:
>> For those with way too much spare time on their hands. I have a CPU
>> based Chinese product which requires some firmware updates (probably a
>> complete rewrite). Finding a pin-compatible part with a low cost
>> tool-chain is also OK. This is not a commercial exercise. CPU has 20
>> pins, SOIC package Pin 5 - I2C Pin 6 - GND Pin 7 - I2C PIN 12 - ADC
>> PIN 13 - ADC PIN 15 - 3V3 Pretty much all of the other pins are GPIO.
>> Almost like ATtiny87, except I2C required either side of the GND pin.
>> I started by using Digikey as the sifting and sorting agent, just
>> wondering if their is a better way. -mark
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