Measuring transfer time

bibibo · Joined: 30 Nov 2009 Posts: 168

Hello, i would like to do a device for measuring transfer time in an UPS applications. UPS topology offline and line-interactive has transfer time line-battery and battery-line around 4 - 10ms. I am not sure if MCU atmega is good choice for this measuring. What do you think ?

AdrianJ · Joined: 16 Jan 2006 Posts: 2483 Location: Queensland

Any AVR is well capable of measuring times in that range.

Just use a timer. Set the prescaler so that the timer does not overflow for the longest interval you want to measure, depends on the processor clock speed.

Read the timer at the start of the interval, eg when a processor line goes high ( or low ). Read the timer at the end of the interval.

Subtract the two, and that is the time interval in timer clock cycles. Then since you know the timer prescaler value, and the processor clock speed, you can work out exactly how long that interval is.

As long as you do the subtraction in bytes ( for an 8 bit timer ) or words ( for a 16 bit timer ), timer rollover during the measurement will not affect the result.