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Understanding the Patch System

Most 'downstream' E-blocks include a patch system that gives you flexibility in the connections that are made between the upstream and downstream E-blocks. The patch system has two parts: link blocks that dictate whether the default connections are used or whether the patch system is used, and the patch connectors themselves.

Looking at this graphic of the sensors board:

For this board when the link blocks are in the default position then the default wiring is chosen. Default wiring is optimized for ease of connection between upstream and downstream boards for the PICmicro range of processors. For example the Tx and Rx lines of the PICmicro are usually on bits 6 and 7 respectively, so you will find that the default connections on downstream boards communications boards (e.g.RS232 board) are for bits 6 and 7. For the A/D board shown above the default connections are as follows:

Bit 0	LDR (Light Dependant Resistor)
Bit 1	RV1 (Resistor-Variable 1)
Bit 2	Digital sensors out
Bit 3	Analogue sensor
Bit 4	Digital sensor in

The bits 0 to 4 have been chosen because on many devices in the PICmicro range the A/D inputs are on bits 0 to 4 of the port.

If you wanted to use another processor that needed the LDR input on bit 3 then you would change the link from the 'default' position to the 'patch' position and use a small jumper wire to make the connection between the LDR output and bit 3 of the D-type as shown in the drawing below: