Jay.slovak said:
Nigel Goodwin said:
However, generally the 'serial' port programmers like this have a reputation for poor reliability, parallel port programmers are generally more reliable - or a proper serial port programmer, which has an onboard processor.
Nigel, do you have personal experience with JDM (or other serial) based programmers? I just want to know, because everybody says that, but I don't know anybody who had such problems... 8)
Not personally, but I've had MANY emails from people who have had problems - the author of ICProg doesn't offer any support (presumably because ICProg supports the JDM?) - so people email ME? instead.
I don't see how it can be very reliable?, even the guy who designed it says it's not - as I've always seen it, it's a very clever piece of design (which is quite obscure in operation!), but designed more as a design exercise in parts reduction than as a practical programmer.
As someone who's been involved in PIC programmers since before Microsoft Windows, I've seen a lot of different types, and a simple look at that circuit shows you could have problems. Serial ports vary greatly on their output voltages, and the original JDM requires it to exceed the RS232 specification. Some of the later designs are better, but can still fail on a port which is still within the RS232 spec.