Pogo Pin Programming

[rq3]

For quite some time I have used standard Pogo pins for programming. The photos show the AXE-027 to Molex KK to Pogo pin sequence. This gives me the option of using the "standard" AXE-027 stereo jack, a 0.1 inch center Molex KK connector, or no connector at all.

The Pogo pins fit a 0.025 or 0.029 inch plated through hole on a printed circuit board, or a Protoboard or Perfboard for prototyping. Saves space and a connector, and has never failed me. I commonly include the fooprint for the Pogo adapter on my PCB layouts, so the Gerber files include it for anyone duplicating the board.

I use these pins:

Pogo Pins "Needle Head" (10 pack)

Pogo pins are little spring-loaded contacts, very handy for making jigs, or making momentary (but electrically solid) contacts. We use them by the dozen for making programming and testing ...

www.adafruit.com

They say the spring loaded needles are 0.030 inches in diameter. They're not. They're 0.025 inches in diameter. I generally just poke the pins through plated through holes on the PCB and don't try to make spring pressure contact.

One good mod would be to add an offset fourth pin connected to ground, so that the pin pattern is "polarized". That way you have less chance of reversing the Pogo sequence and connecting SEROUT to ground. Of course, I've never done that (cough, cough), but the Picaxe survived.

 

[wapo54001]

For quite some time I have used standard Pogo pins for programming. The photos show the AXE-027 to Molex KK to Pogo pin sequence. This gives me the option of using the "standard" AXE-027 stereo jack, a 0.1 inch center Molex KK connector, or no connector at all.

The Pogo pins fit a 0.025 or 0.029 inch plated through hole on a printed circuit board, or a Protoboard or Perfboard for prototyping. Saves space and a connector, and has never failed me. I commonly include the fooprint for the Pogo adapter on my PCB layouts, so the Gerber files include it for anyone duplicating the board.

I use these pins:

Pogo Pins "Needle Head" (10 pack)

Pogo pins are little spring-loaded contacts, very handy for making jigs, or making momentary (but electrically solid) contacts. We use them by the dozen for making programming and testing ...

www.adafruit.com

They say the spring loaded needles are 0.030 inches in diameter. They're not. They're 0.025 inches in diameter. I generally just poke the pins through plated through holes on the PCB and don't try to make spring pressure contact.

One good mod would be to add an offset fourth pin connected to ground, so that the pin pattern is "polarized". That way you have less chance of reversing the Pogo sequence and connecting SEROUT to ground. Of course, I've never done that (cough, cough), but the Picaxe survived.

I have used pogo pins in the past -- by soldering them to the top of a duplicate pcb and using the pcb mounting holes as guides to place the board to be programmed on top of the pins and properly aligned. But that required a rather elaborate layout because I had three separate boards to program to form a "set" and thus had three separate programming boards. Your approach is much better -- one small handheld board to program any board. In my approach I added pins for power ground and +5V to power the board during programming but your idea of an offset pin could be used to provide the +5 so the picaxe is powered up at the same time that you apply the programming circuit. Very cool.

One question -- I don't see the point of the extra 3 pin connector on the pogo board. Why not just solder the wires from the 3.5mm socket directly to the board? Is there something I'm not seeing that mandates the connector?

 

[oracacle]

I would have go with something like a dupont connector, and a hand crafted 3.5mm stereo jack to dupont connector adaptor - or replace the 3.5mm stereo jack with a dupont connector. They are the pitch and pin dimenstions as the molex kk, but without the bulk of polarisation. This might be an issue, it might not (there are way around this without taking up much space). But i can't see it taking up much more space than a set of pads and you dont have to hold it in place while programming takes place.

You may even be better of getting some of those IC sockets with long pins, solder the 3.5mm jack to that and then place the entire thing over the installed picaxe.

nice idea though.

 

[wapo54001]

I would have go with something like a dupont connector, and a hand crafted 3.5mm stereo jack to dupont connector adaptor - or replace the 3.5mm stereo jack with a dupont connector. They are the pitch and pin dimenstions as the molex kk, but without the bulk of polarisation. This might be an issue, it might not (there are way around this without taking up much space). But i can't see it taking up much more space than a set of pads and you dont have to hold it in place while programming takes place.

You may even be better of getting some of those IC sockets with long pins, solder the 3.5mm jack to that and then place the entire thing over the installed picaxe.

nice idea though.

I placed my pads in a row underneath the picaxe chip -- saved space and did not advertise the ability to program the chip.

 

[rq3]

I have used pogo pins in the past -- by soldering them to the top of a duplicate pcb and using the pcb mounting holes as guides to place the board to be programmed on top of the pins and properly aligned. But that required a rather elaborate layout because I had three separate boards to program to form a "set" and thus had three separate programming boards. Your approach is much better -- one small handheld board to program any board. In my approach I added pins for power ground and +5V to power the board during programming but your idea of an offset pin could be used to provide the +5 so the picaxe is powered up at the same time that you apply the programming circuit. Very cool.

One question -- I don't see the point of the extra 3 pin connector on the pogo board. Why not just solder the wires from the 3.5mm socket directly to the board? Is there something I'm not seeing that mandates the connector?

Sometimes a Molex KK is appropriate to the PCB design, so I can just unplug the Pogo adapter, and plug the KK on to the board.

 

[rq3]

I would have go with something like a dupont connector, and a hand crafted 3.5mm stereo jack to dupont connector adaptor - or replace the 3.5mm stereo jack with a dupont connector. They are the pitch and pin dimenstions as the molex kk, but without the bulk of polarisation. This might be an issue, it might not (there are way around this without taking up much space). But i can't see it taking up much more space than a set of pads and you dont have to hold it in place while programming takes place.

You may even be better of getting some of those IC sockets with long pins, solder the 3.5mm jack to that and then place the entire thing over the installed picaxe.

nice idea though.

I don't press the Pogo pins in contact with pads. That would be nasty. I place 3 through holes on the board so that the Pogo pins go through, and stay in place during programming without having to hold the Pogo adapter. At 0.1 inch spacing, the Pogo pins also match Perf and Proto boards. I can't see any use whatever for 3.5mm stereo jacks. They don't fit, their legs aren't long enough, they are expensive, and they are pretty unreliable overall, IMHO.
I haven't used one in years.

 

[rq3]

I placed my pads in a row underneath the picaxe chip -- saved space and did not advertise the ability to program the chip.

Me too. And even with a surface mount picaxe, the pogo needles don't hit the Picaxe with 0.025 inch through holes on a standard 1/16 inch thick board.

 

[rq3]

I have used pogo pins in the past -- by soldering them to the top of a duplicate pcb and using the pcb mounting holes as guides to place the board to be programmed on top of the pins and properly aligned. But that required a rather elaborate layout because I had three separate boards to program to form a "set" and thus had three separate programming boards. Your approach is much better -- one small handheld board to program any board. In my approach I added pins for power ground and +5V to power the board during programming but your idea of an offset pin could be used to provide the +5 so the picaxe is powered up at the same time that you apply the programming circuit. Very cool.

One question -- I don't see the point of the extra 3 pin connector on the pogo board. Why not just solder the wires from the 3.5mm socket directly to the board? Is there something I'm not seeing that mandates the connector?

I kind of like the idea of adding a power Pogo as the fourth pin. It would solve the "polarization" issue, but would make a hard reset problematic.

 

[hippy]

One good mod would be to add an offset fourth pin connected to ground, so that the pin pattern is "polarized".

Another option is to go five pin and then it doesn't matter if you reverse the connection -

PICAXE TX >---(  O====-----.---> PC RX
PICAXE RX <---(  O====---.-|---< PC TX
       0V ----(  O====---|-|---- 0V
             -(  O====---' |
             -(  O====-----'

TX and RX can be swapped if one prefers.

 

[wapo54001]

I kind of like the idea of adding a power Pogo as the fourth pin. It would solve the "polarization" issue, but would make a hard reset problematic.

Well, this is getting complicated, but there is a solution -- I designed a ZIF-socketed "universal" picaxe programming board that included an 08M2 that sensed the computer attempting to program and applied power to the chip only when the computer was ready and thus the chip to be programmed was powered up just as the computer was looking for it. Reset problem solved.

 

[wapo54001]

Another option is to go five pin and then it doesn't matter if you reverse the connection -

PICAXE TX >---(  O====-----.---> PC RX
PICAXE RX <---(  O====---.-|---< PC TX
       0V ----(  O====---|-|---- 0V
             -(  O====---' |
             -(  O====-----'

TX and RX can be swapped if one prefers.

I would vote to keep it compact, with the RTG row as normal, and the +5 in a second row -- that provides what's needed in a small asymmetrical footprint.

0
0 0+5v
0

 

[hippy]

There's the possibility of a 2 x 4-way reversible connector -

   .-----.
TX | O O | 5V
RX | O O | 0V
0V | O O | RX
5V | O O | TX
   `-----'

 

[wapo54001]

There's the possibility of a 2 x 4-way reversible connector -

   .-----.
TX | O O | 5V
RX | O O | 0V
0V | O O | RX
5V | O O | TX
   `-----'

Hadn't thought of this.

 

[johndo]

There's the possibility of a 2 x 4-way reversible connector -

   .-----.
TX | O O | 5V
RX | O O | 0V
0V | O O | RX
5V | O O | TX
   `-----'

Looks like the same kind of configuration as a Type C USB connector...

 

[erco]

I rolled my own 3-pin connector long ago for the simplest layout to connect Goeytex's USB inverter mod to a
breadboard for use with 08M2, 14M2 and 20M2. Works so well that I use it for everything now, I just solder a 3-pin header to PCBs and use a female-female servo cable from the adapter to the PCB. No 5V. Center ground, USB serial out top, USB serial on bottom. I always put the white servo wire on top. Worst case if I reverse the cable: no damage, it just doesn't work in which case I swap it.