Hello,

I am working on a project that is using the 89C66x family (I have 2 668's in my possesion) and I would like to implement something like NoTouch in my project, and I was wondering if I could run some ideas past you guys.

My first problem is that I don't have enough RS232 converters onboard to convert 3 inputs. I'm using MAX232 so it only has two. Which should I choose to allow the FlashMagic and CPEC programs to start the ISP sequence? I was thinking of connecting the DTR (which is supposed to reset the board) to my reset chip. When DTR goes low, the chip goes high to reset it.

I was thinking of having !PSEN on a jumper/switch, but I don't know the behaviour of the FlashMagic and CPEC programs, do they reboot the board at the end? ***This is my important question***: if so, I would have to release the !PSEN before it gets reset, otherwise I will go into programming mode again (I think, can anyone correct me?). Would there be enough time for this to be done manually (ugh)? When it is not programming, !PSEN would be pulled high with a 10K resistor, is that a good idea?

For the ALE, P2.6, P2.7, I will pull these high with a 10K resistor.

My next question is about using SDCC with the safe NoTouch + Touch technique. Has anyone tried this? I like the idea of using the TX line to go into safe mode... has anyone done this with a MAX232 chip? If the TX input is floating, will the TXoutput float as well, or should I use a 10K pullup resistor on here as well.

Whew. That was a lot of typing. If anyone out there can help, the local sports car club and I would appreciate it. I will hopefully be able to improve our timing equipment with this.