AVR Scope Clock H3-1

AVR Scope Clock H3-1

AVR Scope Clock Operating Instructions (for a Tektronix 400 series scope):

The clock requires either an external wall wart, 7-15V DC with a 5.5 mm (OD) power plug, center positive. It is also possible to use a regulated 5V power source on the VCC Power Header. The + side is clearly marked. The +(positive) is on the side of switch S3, the –(negative) is next to the VCCSELECT header. You can make a cable for the regulated 5V power source using the supplied 2-pin female connector (officially called "terminal housing"). The –(negative) side is marked as a ‘1’ on the female connector itself, though the marking is very small. This connector is polarized so reversing the power when using this connector is not possible (provided the cable is constructed properly)

Connect the probes (1X, 10X) or wires to the terminals marked CH1 and CH2. Set the scope in X-Y mode and connect the probes to channels 1 and 2. Turn R8 all the way counterclockwise (maximum image size). Set both channels to DC mode and the voltage range to 0.5V per division. Now turn R8 clockwise to make the image fit your screen. You can tweak the image, for example to make it completely square (8 divisions), by manually reducing the voltage per division value (VAR knob.) If your scope does not support 0.5V per division, reduce the image size by turning R8 until the generated images matches your scope.
Most scopes define CH1 and the X axis and CH2 as the Y axis. Some, for example the Tektronix 485, reverse this convention. As a result, you will need to swap the probes.

Please note that, if the image looks distorted when using probes in 10X mode, you may have to adjust the probe compensation (they usually have a small adjustment screw).

Because this clock uses a low output impedance DAC, it is also possible to use simple wires to connect the clock to an oscilloscope, for example using alligator clips. If you want to use BNC cables, simply install two BNC PC board connectors on the board (Mouser 571-5227161-3.)

Control of the clock is primarily done using the on-board push button switch. This push button switch has 2 actions:

	Long push (> 1 second: keep the button switch pushed down until something happens on the screen)
	Short push (<1 second: push and release the button switch

The long push enters the Time/Date Set mode, the short push enters the Menu mode.

Time/Date Set mode:

	short push advances the current field one
	long push moves to the next field.

Menu mode:

	short push selects the next value (or activates the current option)
	long push moves to the next option.

Changing the time on the AVR Clock using the push button switch:
To change the time, make sure that the Numeric Display does NOT show the current date. If so, change it using the menu. A long push will enter the Change mode. If the Numeric Display is Off, the time will also be changed, even if the Binary Clock Display is active. The clock is stopped when changing time. The value being changed will flash at this point. If the Numeric Display is Off, one of the Clock Hands will flash in an Analog Dial Display. In a Binary Clock Display, the "lights" columns representing the value being changed will flash. A short push will increment the current field (hours, minutes, seconds). A long push will move to the next field, using the current field value as the new time value. Once done with the seconds field, a "Push To Start" message pops up. A short push will restart the clock at the selected time. However a long push will restart the clock at the actual time, as kept by the on-board Real Time Clock. This is handy if you entered the Change mode by accident or if you changed your mind. Change mode times out after 30 seconds of inactivity.

Changing the date on the AVR Clock using the push button switch:
To change the Date, make sure that the Numeric Display shows the current date. If not, change it to display the Date using the menu (Menu-Num:Date). A long push will enter the Change mode. The value being changed will flash. A short push will increment the current field (year, month, day). A long push will move to the next field. The clock leaves Change mode automatically after finishing the Day value. The order of change is Year, Month, Day. This way, the clock can verify the date validity better (number of days per month, leap years etc.) Change mode times out after 30 seconds of inactivity.

Options available on the on-screen menu:

Option	Values	Function	Option	Value	Function
Num	12hr 24hr Hex Date Off	Select Numeric Field to Display	Dial	12hr 24hr Rom Bin Min	Select Clock Dial to Display
GPS	Off -12 .. +12	Select GPS NMEA input using the selected local time zone offset	DST	USA EU Off	Select Automatic Daylight Saving Time for USA or EU
Boot		Reboots the clock	Demo		enter DEMO mode
Chrono	Off On	fractional seconds display	Cal	Off On	Turn Calibration Screen On and Off
Led	On Off	Controls on-board Led	BurnIn	On Off	Turn BurnIn Prevention Off and On
Play	Off Rev FF FR	Fun modes: Reverse, Fast Forward and Fast Reverse	Reset	Off On	Re-initialize the EEProm area of the Atmega168 to "virgin" state.
Name	On Off Edit	User Name Display			Current User Name is displayed below the Menu

Changing an option on the AVR Clock using the push button switch:
A short push will enter the Menu Mode. The option being updated/selected is flashing. Move to the next option by a long push. The options Boot and Demo are activation options. A short push will activate them. The other options are selection values. A short push will show the next selection value. Moving to the next option (using a long push) when the selection value has changed, will activate the selected value and the clock will leave the menu mode.

The AVR clock FAQ provides much more information on how to use the clock and currently serves as the manual.

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