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April 29, 2010
about 5 years ago
Looking at the Arduino sketch, I have two questions that are probably just my lack of understanding
1. Why is the following line repeated twice? Is it a typo or is there some reason the counter needs to be read twice?
frequency = (TCNT1H << 8) | TCNT1L;
2. when resetting the counter registers, shouldn’t interrupts be disabled? Most of the time it shouldn’t matter but I think there is a potential race if a count occurs between the low byte and high byte being cleared?
3. For accuracy sake, shouldn’t the counter registers be cleared immediately after reading? Right now I think you loose counts that occur between reading, doing the math, and updating the lcd.
about 6 years ago
I’m interested in the source code for this, particularly as a learning exercise. I emailed Jyetech and they said it’s not available. However they said it’s simple, “It was based on RC charging time measurement. Charging / discharging was controlled by making associated MCU ports HIGH, LOW, or High-Z."
There is this Arduino tutorial that looks like a starting point: http://arduino.cc/en/Tutorial/CapacitanceMeter
Anyone interested in trying to write new firmware for this? I’m considering using a atmega168 (or even 328) with the arduino bootloader.
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