RV-3049 datasheet(43/65 Pages) MICROCRYSTAL

43 / 65 page

Micro Crystal

DTCXO Temperature Compensated Real Time Clock / Calendar Module

RV-3049

43/65

5.3.3.TESTING THE TIME ACCURACY USING INTERRUPT OUTPUT 1 Hz

The internal Countdown Timer can be used to generate a 1 Hz test signal at the INT output. However, this

procedure is more complicated than using CLKOUT, therefore the following instructions shall be read carefully to

avoid mistakes.

Enable temperature compensation:

•

Select scanning interval 1 s:

set “ThP” = “0” (bit 0 register EEPROM Control)

•

Enable thermometer:

set “ThE” = “1” (bit 1 register EEPROM Control)

Set appropriate test condition using Countdown Timer & 1 Hz INT Output:

•

Disable Timer:

set “TE” = “0” (bit 1 register Control_1)

•

Disable Timer Auto-Reload Mode:

set “TAR” = “0” (bit 2 register Control_1)

Timer & Timer Auto Reload Mode needs to be disabled to allow changes in settings of the Timer Source Clock and

Countdown Timer value.

•

Set Timer Source Clock = 8 Hz:

set “TD0” = “1“& “TD1” = “0” (bit 5&6 register Control_1)

•

Set Countdown Timer Value n = 7:

set register “Timer Low” = 07h (bit 0-7 register Timer Low)

set register “Timer High” = 00h (bit 0-7 register Timer High)

•

Enable Timer Interrupt:

set “TIE” = “1” (bit 1 register Control_INT)

•

Set Timer in Auto-Reload Mode:

set “TAR” = “1” (bit 2 register Control_1)

•

Enable Timer:

set “TE” = “1” (bit 1 register Control_1)

Prepare MCU Software Driver to clear INT signal:

•

MCU clears INT signal:

clear INT by setting “TF” = “0” (bit 1 register Control_INT Flag)

Measuring equipment and setup:

•

Use appropriate frequency counter:

for example Agilent A53132A Universal Counter

•

Gate time:

set gate time to 32 seconds (one complete compensation cycle)

•

Trigger to negative slope:

set trigger to falling edge (negative slope)

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