Inchworm 1.5 reed relay mod (Switched +5V on Target)

[blueroomelectronics]

Here's a sneak peek at the newly redisgned "Inchworm Classic". It's functionally the same as the Original Inchworm but designed for the smaller Hammond 1591A 95mm x 45mm case. It also will feature the 16F876A (same bootloader as the 16F877A)
**broken link removed**

 

[3v0]

I have been "pondering" why the target cable duplicates each signal on both rows. It seems it would have made more sense to use every other line for a ground to reduce cross talk.

 

[Nigel Goodwin]

I have been "pondering" why the target cable duplicates each signal on both rows. It seems it would have made more sense to use every other line for a ground to reduce cross talk.

Makes no real difference, and with being paralleled it give a far wider range of possible connectors you can use. If I remember right?, the official ICD2 only uses a phone connector?.

 

[evandude]

Makes no real difference, and with being paralleled it give a far wider range of possible connectors you can use. If I remember right?, the official ICD2 only uses a phone connector?.

Yeah, and what's worse, the connector on the ICD2 is not an RJ11 (4-pin) or RJ45(8-pin), both of which are common, it's an RJ12 (6-pin) which is very uncommon.

I think the paralleled pins makes sense - you're not supposed to be using a very long programming cable anyway, so the grounds probably wouldn't help, and with them paralleled you can just as easily use a 5-pin single-row header as a 10-pin dual-row header. If one row was all grounds, and a single-row header was plugged into the wrong row, it would short all the pins together and probably damage the target board if it were powered externally.

in my opinion, a 10-pin IDC-style connector is more convenient (and cheaper) than most of the 5-pin header/connector options out there, even if it is a little odd to be using 10 pins as 5...

 

[blueroomelectronics]

in my opinion, a 10-pin IDC-style connector is more convenient (and cheaper) than most of the 5-pin header/connector options out there, even if it is a little odd to be using 10 pins as 5...

Cheap & Convienient you hit the nail on the head. You can also use a five pin Molex if you like. I like that IDC connectors have a strain relief.

 

[Nigel Goodwin]

Another BIG advantage, is that with the connector wired in parallel, you can fit the same connector on Veroboard - if anternate ones were grounded it would make that more difficult.

 

[Andy1845c]

Veroboard

Not to drag this off topic, but where do you get Veroboard? I see you use it in your tutorials, but I can't seem to find it. Looks handy though!

 

[3v0]

Another BIG advantage, is that with the connector wired in parallel, you can fit the same connector on Veroboard - if anternate ones were grounded it would make that more difficult.

I guess if it works it is good enough.

The reason I asked the question is that when using the molex style connector (olimix supplied) there have been times when I have had to drop the RS232 link speed to 19200. I figured with the ribbon cable it would be worse. I suppose if this was a real problem the full speed USB units would be in big trouble. So it must not be.

Could be the loose wires on the cable were picking up noise from elswhere. I was using a breadboard....

Maybe it does not matter since the only real activity is on the clock and data lines.

3v0

 

[Nigel Goodwin]

Not to drag this off topic, but where do you get Veroboard? I see you use it in your tutorials, but I can't seem to find it. Looks handy though!

It's available from almost any supplier in the UK, I usually get it from either RS Components or Maplin. There have been a number of threads where people have given sources in the USA, you might try looking for Stripboard rather than Veroboard (which is the original tradename).

 

[blueroomelectronics]

Well the next Inchworm Classic+ PCB is ready for the PCB factory.

Some changes are the BS250P and SW1 options if you want to control target power or isolate the Inchworm from your project. The switch lets you override the BS250P and allows more current to the target than the BS250P can handle (220ma), it also allows for the target to power the Inchworm. The Power & Busy symbols are now icons and other small changes (like slighty larger holes for the power connector, and the 40pin expansion connector under the 16F877A (makes it easy to test the USB option)).

Of course the real PCBs will be blue!

**broken link removed**