Update: site doesn’t support https so if your browser tries to use the URL “https://…” the site won’t respond. Delete the “s” from https. The picPET page is http://www.leapsecond.com/pic/picpet.htm
]]>(Hmm, well that didn’t work very well, need to reduce the image file size…)
]]>Input Pico Count
10kHz = 9999
50kHz = 49995
100kHz = 99988
120kHz = 119977
150kHz = 144800 Lost it!
200kHz = 144278 Completely wrong!
All results have some jitter, which gets worse with rising frequency.
My code suggests a Pico 1 can detect interrupts up to about 140kHz. But the number that can be managed practically depends on the time taken by the code in the interrupt service routine. I don’t have a feel for how much work an ISR in John’s hobber needs to do. My example does very little work in the ISR, so the rates I’ve measured are as fast as it gets. (John has since suggested by email that the processing his ISR has to do is also short and sweet.)
Code attached. Written for and compiled from the Arduino IDE, so should be familiar to anyone into Arduinos. It works thus: loop() contains a call to delay(1000) that suspends the CPU for 1000mS. However, during that time, the CPU still responds to interrupts, allowing me to count the number of RISING HIGH edges of a square wave received whilst loop() is stopped. The code also toggles an output pin so the delay between input and output can be measured with a dual channel oscilloscope.
Cheers,
Dave
or Google Create a Schematic symbol in KiCad for Tutorials
]]>