Making Things Talk by Tom Igoe

Author:Tom Igoe
Language: eng
Format: mobi, epub
Tags: COMPUTERS / Hardware / General
Publisher: Make
Published: 2011-09-08T04:00:00+00:00

Next, add some code to add a time stamp. First, add a global variable to set the text line height.

int lineHeight = 14; // a variable to set the line height

Add a method to the end of the program, drawReadings(). This will display the date, time, voltage reading, and received signal strength.

Call this method from a few different places in the program; first, at the end of the setup() method:

// show the readings text: drawReadings(0,0);

Next, to draw the latest readings, call it at the end of the parseData() method:

// draw a line on the graph, // and the readings: drawGraph(average); drawReadings(average, signalStrength);

void drawReadings(int thisReading, int thisSignalStrength) { // set up an array to get the names of the months // from their numeric values: String[] months = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" }; // format the date string: String date = day() + " " + months[month() −1] + " " + year() ; // format the time string // all digits are number-formatted as two digits: String time = nf(hour(), 2) + ":" + nf(minute(), 2) + ":" + nf(second(), 2); // calculate the voltage from the reading: float voltage = thisReading * 3.3 / 1024; // choose a position for the text: int xPos = 20; int yPos = 20; // erase the previous readings: noStroke(); fill(0); rect(xPos,yPos, 180, 80); // change the fill color for the text: fill(#4F9FE1); // print the readings: text(date, xPos, yPos + lineHeight); text(time, xPos, yPos + (2 * lineHeight)); text("Voltage: " + voltage + "V", xPos, yPos + (3 * lineHeight)); text("Signal Strength: -" + thisSignalStrength + " dBm", xPos, yPos + (4 * lineHeight)); }

That’s the whole program. When it’s running, it should look like Figure 7-16.

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