SSI / Encoder / Quadrature Counter (Module E7)68C3 Operations Manual North Atlantic Industries, Inc. 12/19/2014Rev: 2014-12-19-0947 www.naii.com Page 273 of 330Interval Timer ControlBit Symbol Description Access Reset Value[15:3] - N/c r 0[2:1] ITDIV Pre-Scale Value00 25 MHz 40 ns01 12.5 MHz 80 ns10 6.25 MHz 160 ns11 3.125 320 nsr/w 00[0] ITEN Interval Timer Enable’0’ Disables the Interval Timer’1’ Enables the Interval Timerr/w 0The interval timer is a 16-bit pre-loadable counter with a programmable clock rate. On activation the counter loads from theInterval Timer Preload Register and starts counting down. When the counter reaches zero, it generates an interrupt (ifenabled), then is automatically preloaded again and continues counting. With the 16-bit preload register and theprogrammable clock interval, interval times up to 65ms are possible. Calculate the interval times using the following formula:Interval Time = Value of Interval Timer Preload Register * Clock periodInterval Timer Clock PeriodsThe interval timer can be used as a reference timer in closed loop applications or as a trigger for a multiplechannel read.
