Can I use QuickWriter to program 4 in-circuit devices at a time?

Submitted by: TechTools


QuickWriter is NOT designed to do multiple in-circuit devices at once. It was specified, designed and verified to do single in-socket, gang in-socket and single in-circuit programming. It is natural to wonder why we did not add gang in-circuit to the list, and to assume that it *should* be able to do it. However, 4 gang in-circuit can be quite different than the other modes. In fact, *single in-circuit* puts about the same demands on the programmer as *gang in-socket*. Had we decided to add 4 gang in-cicuit programming, the basic programmer cost would have increased considerably, making it impossible to make a cost effect, in circuit programmer that could be expanded to single or even 4 gang in-socket programmmg. The basic programmer version would be carrying too much 'baggage' to be cost effective in any but the 4 gang configuration.

In addition to the potentially large increase in loading and signal skew, we loose the ability to determine if the connections are correct and we can not tell if one or more targets are properly powered. Further, we have no control over interactions between the targets.

Sub-question 1: I know you said it is not designed to do it and that you have technical reasons for saying it won't do it in general....but I think it should work anyway. Can I make my own in-circuit cables to adapt your 4 gang socket adaptor to 4 gang in-circuit programming?

You are free to do anything you want as long as you take responsibility for your actions :)

Before you start experimenting with *YOUR* (non-warranty) design....consider:
- what happens if one or more of your targets are not powered up when you start programming.
- what affect does the power-up/down sequencing have on the targets?
- what happens if one or more of your target connections are wrong (plugged in backwards, off-by-a-pin...)?
- what happens if one of the targets has a solder short or other manufacturing fault?
- what happens if one or more targets skew the signals to the point the programming timing specs are violated?
- how do your 4 targets react to having their programming signals shorted to each other?
- how much static load are you adding to the programmer?
- how much capacitive load are you adding to the programmer?
- what happens after you let the magic smoke out of the programmer?....your target?

Sub-question 2: If I attempt gang in-circuit programming despite your insistence it violates your specs, will you provide pinouts, schematics, free repairs or other support to help?

No. (...we *have* been asked...)

In summary: If you use the programmer for its designed purposes, it will serve you well. If you try to use it for other purposes it may or may not function....or survive.