AppMod Protocol

Agent Cobalt

I was wondering if anyone had information on how the AppMod protocol is implemented both on the sending and receiving end because it might fit in perfectly with my project I'm working on. I looked on the website and didn't see anything other than info pertaining to a specific AppMod and a search on the forums didn't turn anything up. Thank you.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Truth can be dangerous... Trust can be deadly.

Bruce Bates

Agent Cobalt -

AFAIK there is no "AppMod protocol" per se, only an AppMod header configuration. Unfortunately, I don't even have a link to provide to describe the header pinout - sorry.

It may or may not be designed with a pass-through philosophy in mind either, as that has never been quite clear to me, nor have I used it specifically for that purpose. My guess is that it isn't but rather is just a common wiring method via a particular header connection configuration (2 x 10 as I remember, but check that).

Just in passing, and before re-inventing the wheel, you might want to take a gander at a potential pass-through methodology (if that is your goal) which has some mileage on it already "micro-Stack" by Pond Electronics in Ireland:
http://www.pond.ie/products/ustack/index.html

My only question with that particular "micro-Stack" configuration is that it may lack sufficient pins to carry the entire cadre of desirable voltages, signals and ports available on the standard Basic Stamps. I just didn't examine it all that carefully. The pin configuration is 2 x 12. Granted, the AppMod header has even fewer pins than that.

It seems a bit of a shame that this wasn't addressed many years ago with some sort of pseudo-standard which all might follow just for cross-compatibility, if nothing else. Just in passing, AFAIK, only the Parallax Stamp AppMods use the AppMod configuration, and I highly doubt it's a patentable item, and thus is freely available as with most non-proprietary Stamp facilities and equipment.

Regards,

Bruce Bates

Jon Williams

Here's the skinny on our "AppMod protocol"

1. Bi-directional serial I/O on a single conductor
·· -- this means all entities transmit in "open" mode; we use Open-True an put a pull-up on the serial line

2. Master header begins with "!" (bang), and usually has a 3-byte id
·· -- my GPS project, for example, will use the header "!GPS"

The rest is up to you.· If you follow these very simple guidelines then anything you build will happily coexist with Parallax AppMods.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax

Bruce Bates

Jon -

Perhaps it should be noted that a series resistor might be appropriate, just in case, due to the single path I/O. I realize that open baud modes don't require it, but if both sides don't use it (by error) trouble could be in the offing.

Regards,

Bruce Bates

Jon Williams

Using Open-True mode causes the entities to only pull the line low; it is never driven, and when a device is done with SEROUT it leaves the pin in an output state. While the 220 won't hurt, I won't get worried about adding it -- at some point we have to take off the training wheels....

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Jon Williams
Applications Engineer, Parallax