How I Made a Digital Multifunction Clock Gauge: (Continued)

By pressing the two buttons at the same time, the unit displays "SU" for a couple of seconds and then goes into setup mode.

In setup mode, you:

Set the clock
Select Fahrenheit or Centigrade mode
Set a coolant temperature alarm threshold
Set an intake air temperature alarm threshold
Set an oil pressure alarm threshold (which can also control the stock OP gauge)
Select AFR or Lambda for your air/fuel ratio display
Set a mode where the display stays at max brightness even when your lights are on (so you can see the gauge when the lights are on during the day)

There is one function gauge function assigned to each button at all times.  You can switch between those two functions at any time simply by pressing the H or the M button. Initially the clock is assigned to the H button and ECT is assigned to the M button.  By pressing and holding one of the buttons, you can rotate through the functions.

It displays a two digit code for each function for a couple of seconds and then it shows the number:

"CL" for CLock
"EC" for Engine Coolant temperature
"IA" for Intake Air temperature
"OP" for Oil Pressure
"FP" for Fuel Pressure
"PO" for "POtential", another word for voltage (the VFD can't do "V"s)
"AF" for Air/Fuel ratio

You can see what function is displaying simply by pressing and releasing the button in case you forget what function is selected.

Clock Function:

The clock is just like the stock clock, except that the colon blinks at a 1 second rate.

Engine Coolant Temperature Function:

The ECT gauge simply displays the coolant temperature in *F or *C.

The ECT alarm threshold default is set at 230*F, but it can be changed in setup mode.  If the temperature goes over the threshold, the alarm output is set to drive an idiot light, the display goes to full brightness, and it starts alternating between "EC" and the temperature.  If you set the ECT alarm temperature to 350*F or 177*C, the ECT alarm is disabled.

Intake Air Temperature Function:

The IAT gauge also simply displays the coolant temperature in *F or *C.

The IAT alarm threshold default is set at 245*F, but it can be changed in setup mode.  If the temperature goes over the threshold, the alarm output is set to drive an idiot light, the display goes to full brightness and it starts alternating between "IA" and the temperature.  If you set the IAT alarm temperature to 350*F or 177*C, the IAT alarm is disabled.  This alarm is important for non-intercooled supercharged applications.

Oil Pressure Function:

The oil pressure gauge simply displays the oil pressure in PSI.

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The oil pressure alarm threshold default is set at 6 PSI, the same as the stock oil pressure gauge sender setting, but it can be changed in setup mode.  If the oil pressure goes under the threshold, the alarm output is set to drive and idiot light.  The oil pressure gauge output is turned off, so if the clock gauge is driving the stock oil pressure gauge, it will drop to a reading of no oil pressure.  The display will go to full brightness and it starts alternating between "OP" and the pressure.

Fuel Pressure Function:

The fuel pressure gauge simply displays the fuel pressure in PSI.

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Voltage Function:

The volt gauge simply displays the battery volts to the tenth of a volt.  Since there is no decimal point on the VFD, I use the colon as a decimal point.  For example, 14.3 volts will appear as "14:3" and the colon does not blink.  That way you know you are not looking at the clock.

Air/Fuel Ratio Function:

If you have a wideband O2 sensor controller that can output the Air/Fuel Ratio with the equation AFR=2*Volts+10, then you can display the AFR on the clock gauge.  It can be displayed in either Gasoline AFR form (Stoich point = 14.64) or generic Lambda form.  If you are using a fuel other than gasoline, use the Lambda form.  Since there is no decimal point on the VFD, I use the colon as the decimal point when in AFR mode.  For example, 14.64 will appear as "14:64" and the colon does not blink.  That way you know you are not looking at the clock.  FYI, since the display can't show 20.00, if the AFR is 20 or greater, "0.00" will be displayed.

If you are in Lambda mode, there is no decimal point.  It is assumed to be to the left of the third digit from the right.  For example, 1.000 (Stoich point in Lambda) will appear as "1000".  A Lambda of 0.863 will appear as "863".

So far the clock gauge is working great for me!

Check out the YouTube video I made of the clock gauge in operation in the daytime: http://youtu.be/WCd4tgn6gVI

Check out the nighttime video: http://youtu.be/y3OBQLLMxys