myke predko wrote:
>
> Hi Jens,
>
> It looks like an interesting circuit - maybe you could give an explanation
> of how it works - According to Microchip's programming specification Iddp
> (PIC Current while Programming) is 20 mA and Ipp (Current sunk at _MCLR
> during Programming) is 50 mA.
>
> I'm surprised that an RS-232 port can source this much current.
>
> Good work, I'm interesting in learning more about it.
>
> myke

It works just like compic-1. A great explanation can be found at:
   http://www.ormix.riga.lv/eng/mchip/c1_tech.htm

The average of TxD is used to generate Vcc (as PWM):
   If ADD ax,k1 results in carry then send t1 else send t2
     where t1 has n+1 bits high and t2 has n bits high.
Data is send as 115200 baud, 8 bit, 1 stop, no parity.
Average is (k1/65536+n+1)/10*(V2-V1)+V1. (V2 = -0.7V, V1 = 13.7V).

Regards,
Jens Dyekjfr Madsen