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For programming Arduino compatible microcontrollers, there are three different connectors in use: ICSP, FTDI or UPDI. Because these connectors are only used during programming and then remains unused, I have found a solution where no physic program connector is needed anymore.

Instead of connector, I use just holes with zig-zag orientation on the PCB. The pin header of the programming tool is than inserted directly into these holes. By the zigzag positions of the PCB holes, the connector pins of the programmer press against the holes and make electrical contact. In practice, this connection is good enough during programming use.

Self-clamping Arduino ICSP program connector with key
Self-clamping Arduino ICSP program connector with key

Connectorless Arduino ICSP / FTDI / UPDI program connector
Connectorless Arduino ICSP / FTDI / UPDI program connector


Example: the standard 2.54mm Arduino ISP connector

I am an inventor and always wonder if something cannot be made better or simpler. For instance, the ISP connector, which is 2x3 header with a pitch of 2.54mm:

Standard Arduino 2x3 ISP header
Standard Arduino 2x3 ISP header

To connect to the ISP connector you could use an adapter with Pogo pins:

Sparkfun ISP Pogo adapter
Sparkfun ISP Pogo adapter

But the adapter must be continuously pressed against the PCB during use. Therefore I invented an alternative:

The connectorless zigzag 1x6 mini ISP connector

My solution has some advantages:

  • No Pogo pins needed
  • In contrast to the Pogo adapter, the connector remains plugged in without any help
  • The construction is simple
  • Small footprint since the pitch is 1.27mm
  • Zero ISP connector cost
  • NEW: key pin prevents incorrect connection

The construction is simple: By the zigzag positions of the PCB holes, the male connector pins press against the holes and make electrical contact. The connector is self-clamping. The idea is inspired by the Sparkfun 1X06_LOCK Eagle footprint.

Connectorless AVR ISP connector
Connectorless zigzag 1.27mm AVR ISP connector

Mini 1x6 ISP adapter

With the mini 1x6 ISP adapter we can connect the zigzag ISP connector. The connector pins are thin and are suitable for the Eagle footprint. It is made compatible with the connector of the programmer USBasp.

Mini 1x6 ISP adapter
Mini 1x6 ISP adapter
Mini 1x6 ISP adapter for the USBasp
Mini 1x6 ISP adapter for the USBasp

Key pin

I have added akey pin which prevents incorrect connection. Note that the other images are without the key pin.

The key pin prevents incorrect connection
The key pin prevents incorrect connection

The key pin is optional, so it can be left unconnected also.

Eagle footprint

You can download the Eagle library part at GitHub.

Mini 1x6 ISP adapter for sale

If there is demand, I can let produce the connector and sell. So tell me if you are interested.

Do you have any comments about the website or problems with shopping? Please let me know.