HAM radio

Crude low frequency counter Used two state machines to generate two square waves as signal sources. Frequency counter measured these two frequencies. Frequency counter input       Pico pin 20 (GPIO-15) 40 Hz sq.wave signal source on      Pico pin 21 (GPIO-16) 25 kHz sq.wave signal source on    Pico pin 22 (GPIO-17) 25 kHz was maximum frequency that could be measured. With 25 kHz input, reading varied from 25000 Hz to 25004 Hz Number of interrupts   in one second  were counted to get frequency. MicroPython code: ##################### # Filename CrudeFc1.py import time from machine import Pin import  rp2 # global variable H2L = 0 # Interrupt handler (ISR) def h2l( void ):     global H2L     H2L = H2L + 1           def frequency():     global H2L     fin.irq ( handler = None ) # Int. disabled     H2L = 0     fin.irq ( handler = h2l, trigger=Pin.IRQ_FALLING ) #Int. enabled     time.sleep(1)  # gate time of ONE SECOND     fin.irq ( handler = None ) # Int. disabled     return(H2L)       ###