Connectorless self-clamping zigzag TAG In-Circuit Programming connector

Published: 14 June 2018
Last updated: 21 June 2023

For (TAG) programming and testing, I don’t use physical connectors on the PCB but connectorless self-clamping zigzag connectors. The pin header of the programming tool is inserted directly into the holes. By the zigzag positions of the PCB holes, it provides lateral pressure, sufficient to grip the pins and allow good connection. For use as for programming and testing, it works fine, I have never experienced any contact problems.

Connectorless self clamping zigzag TAG connectorConnectorless self clamping zigzag TAG connector

The advantages of the connectorless TAG connector

  • Zero cost per board
  • No mating connector required on the PCB
  • Tiny footprint
  • It can only be inserted the correct way round

Self-clamping TAG / Arduino ICSP program connector with key

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

Connectorless TAG / ICSP / FTDI / UPDI program connectorConnectorless TAG / ICSP / FTDI / UPDI program connector

Self-clamping 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 headerStandard Arduino 2x3 ISP header

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

Sparkfun ISP Pogo adapterSparkfun ISP Pogo adapter

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

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 TAG / AVR ISP connectorConnectorless zigzag 1.27mm TAG / 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 adapterMini 1x6 ISP adapterMini 1x6 ISP adapter for the USBaspMini 1x6 ISP adapter for the USBasp

Key pin

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

The key pin prevents incorrect connectionThe 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.

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