Sundstrand Corporation

David Hatten

Abdul Rashid

Barry T Drager

Joe Foster

Walter Fry

This invention relates to a method of testing an n-bit programmable counter. It is desired to test the n-bit programmable counter in fewer than 2.sup.n cycles. Accordingly, a counter value output on the counter is coupled to a variable increment rate input on the counter. Each bit of the counter is reset to a binary 0 initial state. A binary 1 state is loaded into a carry-in bit of the counter and the counter is iteratively doubled, by means of the coupling between the counter value output and the variable increment rate input, until a carry-out bit of the counter assumes the binary 1 state to thereby allow the counter to be fully tested in n+1 iterations. The counter value output and the variable increment rate input are decoupled from the counter when the counter is not being tested. The counter is provided with a parallel load input to allow simultaneous resetting of each bit. Intermediate counter values may be checked to provide a means for localizing errors within the counter.

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Belvidere, IL, United States of America

David Hatten