Hello, i have a question about the QTR-8RC and QTR-8A, which of these is the fastest at the moment to take the readings? i know that depends of the frecuency clock of the microcontroller and other things, but in general, which of these can be read more faster than the other, at a clock rate of 20 MHz for example. thank´s for your help.
“my english isn´t very good”
Well, basically, the timing difference in for each sensor depends on two different things. For the Analog sensor, it’s purely how fast the Microcontroller can (and is programmed to) convert analog to digital. For the RC-timed sensor, it actually is a function of the sensor input-capacitor ratio. From the RC sensor page, the max time, which is when the sensor sees black, can be a few milliseconds, while the minimum time (white surface) can be a couple tens of microseconds.
An Arduino (mega328p) at 16Mhz read analog in about 112us. I don’t know what the max speed is, but there is quite a bit of overhead in Arduino code.
A 16F882 can sample and read an analog pin in about 25us at 20Mhz.
So I’d say the analog version is going to be faster.
Thank you for asking this question, because I was actually curious about the results myself. This gave me a half decent reason to look it up.
EDITED: For mistake. The min RC time is tens of microseconds, not seconds.
thank’s for the reply.
