<div dir="ltr"><div>Yup you'd need huge volumes to make 3c micros work. It might have been less costly to convince the customer to bin those parts and start again with something else :-).</div><div><br></div><div>At 10k volumes there are quite a few sub-$ STM32s and more from other vendors. You then have a proper development/debugger set up, proper C, proper everything.</div><div><br></div><div>It stuns me when I see people designing in a PIC16xxx to "save money" or "reduce power" in a system with a 20k unit lifetime when there are so many easier to use options out there that can provide a better result faster.</div><div><br></div><div>Now that China has latched on to RISCV in a big mway maybe we'll see a whole lot of 10 cent RISCV chips in the next few years.<br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Jun 24, 2021 at 6:48 PM Stephen Irons <<a href="mailto:stephen@irons.nz">stephen@irons.nz</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div id="gmail-m_-3747680447272875138geary-body" dir="auto"><div>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. </div><div><br></div><div>Perhaps some of their other series have a different pinout. See <a href="http://www.padauk.com.tw/en/product/index.aspx" target="_blank">http://www.padauk.com.tw/en/product/index.aspx</a></div><div><br></div><div>In case you are attracted to 'the 3c microcontroller'</div><div><ul><li>C-like language, but really just assembler with some C syntax for loops and conditionals, etc.</li><li>No stand-alone command-line compiler, so cannot automate building, etc.</li><li>Home-grown IDE with all of the disadvantages of a home-grown IDE.</li><li>Windows only tools.</li><li>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.</li><li>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.</li><li>In-circuit programming needs dedicated pins or careful thought as it needs high voltages.</li></ul><div><div>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).</div></div></div><div><br></div><div>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.</div><div><br></div><div>I would use an STM32 or similar for a dollar or two, and get the hardware to do stuff that hardware is good at.</div><div><br></div><div>Stephen Irons</div><div><br></div></div><div id="gmail-m_-3747680447272875138geary-quote" dir="auto"><br>On Wed, Jun 23, 2021 at 13:10, Mark Atherton <<a href="mailto:markaren1@xtra.co.nz" target="_blank">markaren1@xtra.co.nz</a>> wrote:<br><blockquote type="cite"><div style="white-space:pre-wrap">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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