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Full Cycle Encoder Interface Circuit

IP.com Disclosure Number: IPCOM000061918D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Floyd, RE: AUTHOR [+4]

Abstract

This circuit arrangement receives inputs from an incremental position encoder and creates up and down counts to be fed to a standard counter. These counts will always be correct regardless of vibration in the driven element, the shape of the inputs from the transducer, or noise on the feedback line.

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Full Cycle Encoder Interface Circuit

This circuit arrangement receives inputs from an incremental position encoder and creates up and down counts to be fed to a standard counter. These counts will always be correct regardless of vibration in the driven element, the shape of the inputs from the transducer, or noise on the feedback line.

The circuit arrangement disclosed herein is an improvement over the previous state of the art in that one count is made each time either input from the encoder changes state. This doubles the resolution of the previous interface circuit.

The drawing is a block diagram of the circuit. Schmitt triggers on each input line provide enough hysteresis to correct for poorly-shaped input signals, and filter out some of the electrical noise, double the resolution and complete immunity to chatter. One of the latches in the /1 memory is set whenever the /1 input changes state in either direction. This causes the clear /2 one-shot to clear the /2 memory latches and the invert latch. The count delay latch is clocked on to allow a count pulse if the count enable circuit determines that this change was a valid count. The direction latch (not shown) is also clocked, and it will set or clear depending on the invert latch and the latched states of the /1 and /2 inputs. The direction is determined by the two latched inputs being the same or not, but counting on each input change requires that this sense be in verted for /1 change and left alone for /2...