Fluke 8050A LED display with continuity tone

[jpwolfe31]

Another Fluke 8050A LED display project, but this time with a continuity tone addition.

There are two versions of the continuity tone software.  The first version is named LED_8050A_TM1637_Display_Cont.  This code enables use of the TM1637 LED Display driver.  It also adds a continuity test with a tone using the output to the LED display to determine if there is continuity.  Continuity is checked each time the display is updated (2 times per second) when the 8050A is set to the ohm function in the 200 range. 

The second version is named LED_8050A_TM1637_RT_Cont.  This version is the same as the first version but instead of using the output to the LED display to determine if there is continuity, the software samples the voltage on the rear lead of R8 (the 220k ohm 2 watt resistor) of the 8050A.  This provides for a real time continuity check without any display update delays.  Voltage for the continuity check is read at the rear lead of R8 through an added LF347 op amp configured as a voltage follower buffer having high input impedance.  This is followed by another LF347 op amp configured as an inverting 10x amplifier.  This produces a voltage in the correct range for the ATmega328P to read through its analog input at A5.

Both of these versions could be used without changing the original display if one just wanted to add a continuity tone.

Code and full description here:  https://github.com/jpwolfe31/8050A-Continuity-Tone-and-LED-Display