Nuts and Volts - July 2014

Here’s how it’s done:

Line 1: Serial.print (“!POBJ lbar_84 =
 dev\\bars\\bar_hor_red_”);

The first line simply outputs a portion of the bar graph without the actual number appended at the end:

Line 2:  Serial.print (sensorValue / 102);

This line takes the sensorValue that can range from 0 to 1023, and divides it by 102 to create a “0 to 10” integer value result. This, then, corresponds to the number of the bar graph to send to MakerPlot:

Line 3:  Serial.println (“.gif”);

The next line appends the .gif suffix to the LED bar graph name; the Serial.println instruction also sends a carriage return, thus terminating the MakerPlot instructions. Note that Line 1 and Line 2 used the Serial.print that doesn’t apply a carriage return:

Line 4:  Serial.println ();

While this was a simple example of how to send controls to MakerPlot directly from a micro, What this code snippet does is construct the name of the LED bar graph image based on the potentiometer value (or sensorValue in the sketch itself).

The last line simply sends a blank carriage return that MakerPlot interprets as the final end of the previous instruction. The final result is the LED bar graph with the appropriate number of lit segments. Since we’ve already placed the first LED bar graph in the setup, all MakerPlot needs is the image name we give it from these four lines.

The Sketch in Action

First, we need to run MakerPlot with the My_Interface.spm Interface. When the red rocker switch is clicked and the sketch is run for the first time, the two controls are placed in the rectangular area as in Figure 4.