Nikolay_Po (06.06.2016 16:52 - 16:55, просмотров: 53) ответил Николай Коровин на Подскажите битте 16-битный счётчик с регистром сравнения на выходе. Должен держать 200 МГц и прогружать регистр одним махом по фронту, т. е. иметь 16 входных ног. По сути, аналог обычных атмеговских таймеркаунтеров, но очень шустрый.
На сколько часто будет прогружаться регистр? http://mcs.uwsuper.edu/sb/Electronics/FreqCounter/
"The output of the comparator is connected to a 4-bit asynchronous binary counter SN74LV161A with maximum clock frequency of 220MHz when powered from 5V. The counter is used as a pre-scaler to the PIC's counter TMR1. It divides the input frequency by 16, so the PIC gets maximum 10MHz which is in the range of the minimum input clock period of 60ns (this corresponds to approx. 16MHz) required for TMR1 in the asynchronous mode. Furthermore, the pre-scaler improves the clock waveforms for TMR1 which is a bonus. The TMR1 16-bit counter works in asynchronous mode, which is needed for counting external with respect to the PIC frequencies. All 4 outputs of the counter are connected to PIC and the counter value forms the 4 LSB of the measuring frequency."
См. ссылку. Там же:
"As soon as the frequency counting interval is over, the PIC sets the ENP input of SN74LV161A low, thus preventing it from further counting. After this the values of all counters are read and processed for displaying."
Но только 4 разряда. Может, оно каскадируется?