Summary of Open-Source SWD Programming Adapter
Summary: I redesigned a compact SWD programming adapter to replace an AVR-era 6-pin ICSP pogo tool. The new surface-mount footprint supports pogo pins or a 0.05" ribbon-cable connector and an optional soldered 0.05" header for bench debugging. A small ST-Link-mounted board includes an LED that indicates target power and a jumper to power the target from the ST-Link regulator, simplifying mass pogo-programming of low-power PCBs.
Parts used in the SWD Programming Adapter:
- PCB for ST-Link adapter
- LED (power indicator)
- Jumper (to enable ST-Link onboard regulator to power target)
- 0.05 inch pitch ribbon cable connector
- Pogo pins (4-pin set)
- Pogo pin mounting holes on PCB
- 0.05 inch pitch pin header (optional soldered header)
- Ribbon cable (premade cable compatible with connector)
After making the switch from AVR to STM32 microcontrollers, I redesigned my old 6-pin ICSP pogo-programming adapter for SWD. The new design allows programming with pogo pins or a small pin header soldered to the pogo pads for debugging, all with the same cable. The footprint uses surface mount pads only, so it can be placed on even the most compact board layouts.
The ST-link adapter
I designed a small PCB which mounts directly on top of an st-link programming pod. The board has an LED that lights up when the target is powered, and also has a jumper that powers the target from the st-link’s onboard regulator. This feature is great when mass pogo-programming low-power PCBs.
The board also has a 0.05″ pitch ribbon cable connector. This connector is quite rugged and easy to use, and has the same pitch as the programming footprint that it interfaces with. Premade cables are available from Digikey for a fairly reasonable price.
PCB Footprint and Header
The PCB footprint is nearly the same as my old 6-pin footprint, but without any vias for alignment. This footprint could easily be modified to use vias to align the pogo pins, but I find that aligning 4 pins is quite easy even without alignment features. The footprint is small enough to fit on pretty much any design, and should optimally be placed on the edge of the board so a pin header can be soldered on, if desired.
One of the best features of this footprint is that you can solder on a 0.05″ pitch header along the edge of the board. The ribbon cable from the programmer can plug right into this connector without any adapter. This is great for debugging on the bench when you don’t want to solder wires directly to the pads or hold a pogo programmer in exactly the right position for extended periods of time.
Pogo Programming Adapter
The pogo programming adapter is a very simple board, with only a ribbon cable connector, an LED, and pogo pin mounting holes. Inserting and aligning the 4 pogo pins is quite easy as opposed to the 6 and 8 pin versions I used previously. When connecting to a powered target, the LED is a nice indicator that at least two of the pogo pins are making good contact with the board.
Read more: Open-Source SWD Programming Adapter
- Can the adapter be used with pogo pins or a header?
Yes. The footprint supports pogo pins and a 0.05 inch pitch header can be soldered along the board edge for cable connection. - Does the ST-Link adapter indicate when the target is powered?
Yes. The board includes an LED that lights when the target is powered. - Can the ST-Link power the target?
Yes. There is a jumper that powers the target from the ST-Link onboard regulator. - Is the footprint surface-mount only?
Yes. The footprint uses surface mount pads only so it can be placed on compact board layouts. - What pitch is the ribbon cable connector?
The ribbon cable connector uses a 0.05 inch pitch matching the programming footprint. - Are premade cables available for the connector?
Yes. Premade cables for the connector are available from suppliers such as Digikey. - How many pogo pins does the adapter use?
The redesigned adapter uses four pogo pins. - Is alignment difficult without vias?
No. The article states aligning four pins is quite easy even without alignment vias. - Where should the footprint be placed on a target board?
It is optimal to place the footprint on the edge of the board so a pin header can be soldered on if desired.
