Dear A.S.,
- the sunrom project appears to be a commercialized version of Wichit Sirichote's free project, therefore the sources from there would most probably apply - http://www.8052.com/forum/read.phtml?id=124534 . I have no other sources, nor did I try to build that programmer as such.
- Some 6-7 years ago I have built a 'C2051 programmer for my own purposes from scratch, simply based on the information given in '51 datasheet, around an AT89C55 (which also holds the to-be-burned program), some five or six years ago, and it is sort of standalone (not completely, but the PC only says "burn" and in fact could be easily replaced by a button, and the only feedback is again into the PC) - but I cannot simply give away the sources of that - I hope you understand. It is not portable nor rugged as we did not need to be it such. The reason for building it was, that we needed to modify the to-be-burned binary for each product in a way we could not reasonably accomplish in PC - and at the same time this provided at least some protection of the binary (this way it's somewhat harder to steal than if it would be on the PC and burned by a commercial programmer) and some control over who burned what. I just want to say that there is no magic in it. It still works as expected.
- I don't think it is a big issue with those 1% resistors. The sole purpose of that whole circuit is to provide switchable 5V and 12V (or whatever it is) onto pin 1 - the high voltage in case of 'C2051 is NOT a programming source, just a logic level to "unlock" the progamming circuit (i.e. a security measure, so that it cannot get erased/reprogrammed in the target application by accident). There are numerous ways how to achieve that. In "my" programmer, I used two simple optocouplers to switch the required voltages to (produced by standard 78xx regulators) to pin 1.
- I don't ever think an LCD is necessary - all I'd put on is several LEDs to indicate the progress and success/failure of programming. I'd also won't complicate the things - I'd put one to-be-burned binary per EEPROM, and perhaps "ruggedize" the EEPROM insertion (a "smartcard" form of EEPROM comes into mind, but I don't know how well available that might be in India).
- I don't quite understand what exactly do you expect from us. Clearly, we won't give you a ready made solution, just hints.
Jan Waclawek
PS: No need to call me Dr, please, call me Jan. :-)
