| ??? 12/31/04 12:14 Modified: 12/31/04 12:16 Read: times |
#84163 - HCT driven with RS232. Responding to: ???'s previous message |
Dear Ijaz,
Thanks for your reply, The circuit that you have posted can't be tried on my exixting PCB since it will require a lot of change and since PCB is a PTH I think it will be really dificult. I am also a lot tired trying ICP but not successfull I also spoke with some of my friends who have tried ICP circuit earlier but they too said they couldnt make it work and ultimately purchased a professional programmer for ICP. I think I will have to temporatily leave the idea of using ICP. I will use my existing board just for developing the software for my next LPC932A1 project and when I am really into production I will make a new ICP programmer or If it doesn't work even with second attempt I will buy one. With second attempt I will try your ciruit too and I will let you know how it worked. Ijaz said:
PS: I see some other problems in the circuit. For example IC2B is a HCT NAND gate driven by +12/-12V from COM port (although you have 47K in series) and this gate turns on Q1 which controls VDD to LPC932A1 (having prog90x.hex). Why not use a spare gate in MAX232 to convert this signal to proper level and then use it as VDD control? As I have earlier said my this circuit is essentially keil MCB900 +some other things such as ICP, 2 Leds, power transistor etc. Keil MCB900 use the same ciruit for ISP programming of LPC932A1 i.e. HCT getting signal directly from RS232 line and it works very well not just my circuit but several thousand MCB900 that keil has sold. I never went into details of this kind of arrangement. I copied ditto from keil MCB900 schematic. Thanks & Regards, Prahlad Purohit |
