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Altera_Forum
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16 years ago

Strange problem in synthesis of counter

Hello, I am currently writing a learning module on creating a mod-counter. When I attempt to demonstrate the concept of a mod-6 counter using the 4count symbol and a NAND2 as feedback to the CLRN...
Altera_Forum's avatar
Altera_Forum
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16 years ago

The asynchronous feedback modulo logic only works with an asynchronous ripple carry counter. Here the stages are toggling one after the other. I have build many similar counters with discrete TTL and CMOS logic in the past.

4count is a synchronous counter, so all outputs are toggling at the same time. Depending on accidental delays, you can get a reset glitch during the transition 3->4.