SHAFT ENCODING

Shaft encoder for quadrature signals
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This circuit shows how to interface the Hewlett Packard HCTL2016 quadrature shaft encoder integrated circuit to the TDS2020F computer. By using other chip selects you can add multiple units making the arrangement suitable for a variety of robotic applications. The file #SHAFT.TDS supplied with the UPDATE SERVICE, page 38, contains support code.

The Forth word POSITION updates a 32-bit counter and by putting this inside a regular interrupt routine you can read the shaft position at any time by looking at the 32-bit variable COUNTER .