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Digital Output / LED Indicators in SimVimCockpit


You can configure as many LED indicators for your cockpit as you need because SimVim can control multiple LEDs with one controller output pin using the common "serial-to-parallel shift" method. The register chip connected to this output receives N bits of information one-by-one, sequentially shifting them to the corresponding parallel N outputs and "latching" them at the end of the data sequence.

The 16-channel DM13A LED driver is used in SimVimCockpit Interface to provide multiple digital outputs. This driver is a shift register with a latch (memory), that also provides constant-current outputs for 16 separate LEDs or LED bars. Besides the DM13A you can use any other similar drivers listed on the "Components" page.

-------- Wiring ------>

The wiring is quite simple (see the diagram above) - you need to connect common GND, 3 signal lines - two common "D/L" lines and one control signal "S" connected to the pin assigned in the configurator. The driver has 16 constant current outputs and each single output can sink the current by 3 ... 60 mA. The LED operating current can be set with one reference resistor connected to the Rext input (terminal #23), that can have resistance between 1 ... 22 kΩ and defines the current (and brightness) for all LEDs. You can connect a variable resistor to adjust the current as needed and then replace it by a constant resistor.

The driver itself can be powered using +5V output on the master board, but for all LEDs you need to have another power source (+Vled) that can vary from 5 to 15 V, depending on your LEDs type.


Implementation options

If you think you need to make PCBs for each driver or driver set, no, you don't necessarily need them. You can use a bare DM13A chip inserted into the small "breadboard" that can be taped to any part of your cockpit.

Also, using DM13A drivers in DIP casing, you can solder thin wires directly to the driver pins. Then this driver can be attached to the surface near the LED group using thermo-glue or 2-side duct tape..

See more tips about wiring your cockpit on the "Wiring" page.


Serial LEDs output capacity

In SimVimCockpit you can have from 8 to 64 serial LEDs connected to one output, depending on the location of LED groups in your panels. For example, you may have 16 LEDs controlled by one single DM13A driver connected to one pin, and another group of 30 LEDs controlled by 2 daisy-chain connected DM13A drivers on another pin.

The maximum number of LEDs with serial shift control on one output is 64, for that you can use 4 daisy-chain connected DM13A drivers. For this you need to use the driver's Dout terminal #22 as "D" input signal for next driver in chain:

As such, you can have either one or several separate LED groups located in different areas of your cockpit. Each group has 3 input signal lines (besides power lines). You need to connect the "S" input to the Master board pin assigned as extended output for this group of LEDs. Two other signal inputs - "D" and "L" - should be connected to the corresponding common bus lines ("D" and "L" output signals).

As the LED drivers alternative, you can use 8x shift registers, such as 74HC595 chips or breakout boards.


Configuration

First, to "connect" a Serial driver in the configurator, click an empty pin and select the "Add LED Driver, Serial" extension type (not "Output Mux"!)

In the configurator image map or parameter table, select any parameter suitable for digital output (such as annunciator) or variable parameter for linear LED graph indicator, and assign it to one of the LED Driver outputs (from 0 to 63)

LED BarGraph Indicator

To display some parameter value as a linear or circle graph indicator you can assign it as "LED Bar Indicator (series of LEDs)" in the configurator. Then, you have to select only the output number to which the first LED will be connected and then insert the number of LEDs your indicator includes.

In SimVimCockpit you can configure several digital outputs for a multiple-LED indicator to display the current value of any numeric parameter as a linear or circle graph. This can be just 3 separate LEDs for 3 positions or a LED bar indicator with 3 to 64 sectors. In this example diagram the LED bar with 6 sectors is connected to outputs #10 to #15, and output #8 is used as digital control signal for some other electronics:

All LEDs forming this indicator should be connected to the first specified digital output and all consequent outputs without skipping. You can use either separate LEDs arranged in the form you need (circle or linear) or LED bar graph indicators.


Note: The LED bar display modules with built-in voltage-controlled driver (like LM3914N) can not be used with digital outputs - you need to use PWM-controlled output for such displays instead.








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