Hello everybody,

I got Mahmood 's schematic of Atmel ISP cable in his previous post. It is not a cable only; it is exactly an interface between parallel port and SPI with an IC buffer. However, I have no problems to built it based on his schematic. Thank you, Mahmood. In the past, I usually use AT89C52 because of its dirty cheap price (US$1.10/ea). But I am tired of parallel flash programming. It is not funny to pull uC out and insert it into the socket 20 times/day because I usually make mistake every 20 line code in assembly :-( (poor programmer!) As Erik and Mahmood 's recommend for new design, I may switch to P89C52Rx2 if it is not too expensive (<US$10.00/ea ?). Another question, my design always has 2-wire RS485 for multidrop communication and I think no way to use IAP via RS485 (no signals to control Reset and /PSEN pins of uC) , or am I wrong? Adding a RS232 port for IAP is the only way to go?

Writing code is an interesting job, debugging makes me headache, loading code into uC flash memory is very boring, although it is much better than OTP and ROM mask. So thank you everybody helping me to get a convenient flash loading.

Nice weekend,

Hung Lam