This page will document an automated Flex-Cable tester for the g-2 tracker. The idea is to automatically verify that there are no shorts or opens in a flex-cable, given connectors on both ends interfaced to a computer.

• Schematic: ​TestBeam_A.pdf

There are a total of 144 pins on a Flexi (64+80 connector pins) There are ~44 non-GND nets in this design. We need to be able to drive each one to logic 0 or 1 from one end of the cable. The remaining 100 pins need to be measured as inputs, with a pull-up resistor to sense shorts. So, we need:

• On the ZIF end:
  • 44 outputs
  • 19 inputs
  • 1 GND
• On the ASDQ end:
  • 79 inputs
  • 1 GND

An ATmega328 provides easily 15 I/O plus I2C and UART (13 on Arduino because of XTAL) There exist e.g. PCA9555 I/O expanders which connect to I2C and provide 16 extra I/Os.

So on the ZIF end we could use e.g. an ATmega328 (15 I/O) plus (3) PCA9555 giving a total of exactly 63 I/O which is what is needed.

On the ASDQ end we could use another ATmega328 plus (4) PCA9555.

Alternatively we could build a (otherwise useful) Arduino I/O expander shield with a lot of I/Os on standard ribbon cable headers and then two boards with the flexi connectors.

See: ​Centipede Shield