[chbot] Help track down a processor - the double chox fish challenge

[Charles Manning]

Since I2C can be bit-banged very easily, these could very well just be
GPIOs.

I wouldn't put money on the 8051 since there are huge numbers of
architectures out there - including some that are used only in China (eg.
Padauk - 3 cent micros). Many of these bottom end devices are OTP.

Does it have any tracks going off to something that might be a debug
header? If it supports JTAG it would probably identify itself quite quickly.



On Wed, Jun 23, 2021 at 1:58 PM Mark Atherton <markaren1 at xtra.co.nz> wrote:

> Unsure if China or Taiwan.
>
> Pin 5 SCL, Pin 7 SDA
>
> No async brought out, so don't know if UART present.
>
> ADC is quite possibly a single differential channel.
>
> EEPROM is off-board.
>
> No markings on CPU.
>
> Jelly bean is 0603, with sprinkling of SOT-23 transistors.
>
> Can't see a date-code on anything, but technology smells of maybe 8 yrs
> old; FLASH was pretty popular by then.
>
> If it's a Chinese part, will put a small bet that it will be 8051 based
> core.
>
> HTH
>
> -Mark
>
>
>
>
>
> On 23/06/2021 1:48 PM, Eliot Blennerhassett wrote:
> > On 23/06/21 1:10 pm, Mark Atherton 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.
> >
> > Some clarifying questions...
> >
> > ? China or Taiwan ?
> >
> > ? I guess there are no markings at all on the chip?
> >
> > ? Which pin is SDA and which SCL ?
> >
> > ? You're assuming it is reprogrammable (i.e. flash based) ?
> >
> > ? Likely to have EEPROM ?
> >
> > ? Has UART ?
> >
> >
> >>
> >> 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.
> >
> > Ask on electronics.stackexchange.com ?
> >
> >>
> >> -mark
> >>
> >>
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