License and System Diagram

A project log for OpenPnP Automatic Tape Feeder

An Automatic tape feeder for the OpenPnP project with integrated control and system communication.

andrewAndrew 08/17/2014 at 05:380 Comments

Just a quick update today on license of the work and the system diagram.

In actually stopping to look at the license for this project as opposed to slapping on the common GPL Vx license I found one the mirrors many of my sentiments about licensing. the every classy, ever tasteful, not at all unprofessional


As i stated, it is a classy affair. In reality the license is essentially identical to releasing the work into the public domain. However with a little extra flourish and political sentimentality. The wiki is here, as well as some interesting discussion on the professionalism and challenges of using the DWTFYW.

System Diagram

This project does not take a lot of rocket science to work out. The system is relatively simple with communication to a host system (the PnP machine) and a few outputs to motors and sensors for the closed loop control. 


An SPI bus provides simple communication from the host to all feeders. This allows the communication of additional information such as fault conditions, remaining components, feed rates, component pitch, low part count warmings etc. SPI is a simple protocol that most devices can interface with and reduces wiring complexity from the host.

IO signals

To improve functionality and allow for a reduced complexity system an input and output are provided. The input is an incremental part feed signal triggered on the rising edge. The output is an open collector drain signal for fault indication, such as a mis-feed, jam, empty feeder etc.


Several motors and potentially a solenoid are going to be required in this system. Closed loop feedback is achieved with a photo interrupter over the holes in the tape. This ensures no mis-feeds occur in the system and can detect jams.

In a further update further options for the control system will be analysed.