Update README.md

project11/README.md

@@ -19,22 +19,57 @@ The first step is to take the materials developed in project 10 with the 1602 LC
 starting position and add to that solution the materials developed in project 05 with the
 active buzzer.
 
-The displayed text will contain a counter that is incremented. Each time the 1602 LCD display text
-is changed the buzzer will emit a short tone. The tone will vary depending on the value of the counter
-mod 5 so there will be a total of 5 different tones which are emitted in a series which is then
+The displayed text will contain a counter that is incremented once every three seconds. Each time the
+1602 LCD display text is updated the buzzer will emit a short tone. The length of the tone will vary
+depending on the value of the counter mod 5 plus 1 times 400 milliseconds so there will be a total of
+5 different tone lengths from 400 ms to 2000 ms (2 seconds) which are emitted in a series which is
 repeated.
 
 ### Next phase - Adding Lesson 14
-Adding Lesson 14 involves adding the tilt sensor to the circuit. Using the tilt sense allows us an
+Adding Lesson 14 involves adding the tilt sensor to the circuit. Using the tilt sensor allows us an
 additional mode of user interaction, tilting or rotating the board in one plane so that the tilt
 switch indicates that the board has changed its position.
 
-Text is displayed on the 1602 LCD Display to indicate the tilt sensor readings. In addition the buzzer
-is sounded as tilts are detected.
+The first line of the 1602 LCD display will show the counter text and the buzzer will emit tones
+of varying lengths of time similar to the previous iteration of this project.
+
+Text is displayed on the second line of the 1602 LCD Display to indicate the tilt sensor readings.
+In addition we will add an LED which will become lit when the tilt sensor indicates a tilt condition
+and then turn off when the tilt is corrected.
+
+#### Tilt Sensor
+
+The tilt sensor included in the kit uses the SW-520D tilt switch soldered to a micro-PCB that contains
+the necessary components to provide a digital output to indicate tilt or not tilt. The input voltage
+is 5v so the 5v rail of the Raspberry Pi is used to power the tilt sensor package.
+
+The `digitalRead()` function of the wiringPI library is used to determine if the tilt sensor package
+is holding the Raspberry Pi pin LOW, indicates not titled, or HIGH, indicates tilted. When the tilt
+switch is vertical the state is Not Tilted so the output is digital LOW. As the tilt switch is
+rotated so that the barrel of the tilt switch changes from vertical, 90 degrees or orthogonal to the
+ground or horizon, to horizontal at some point the internal balls within the barrel will move
+away from the contacts causing the state to change to Tilted so the output becomes digital HIGH.
 
 ### Final phase - Adding lesson 15
 
 In the final phase a potentiomter is added to allow a voltage output detected by a pin to be varied.
-As the potentiometer is manipulated the voltage detected is displayed on the 1602 LCD Display. The
-buzzer is used to provide aural feedback by changing the tone emitted based on the voltage level
-of the potentiometer.
+As the potentiometer is manipulated the voltage level detected is displayed on the 1602 LCD Display.
+
+In addition the tilt switch is used to detect tilting with the LED giving a visual indication of a
+tilt.
+
+The first line of the 1602 LCD display is used to display the potentiometer setting along with the
+counter text. The buzzer will be emitting the various tone lengths as governed by the counter value.
+
+The second line of the 1602 LCD display is used to display the tilting information along with the
+LED visual indicator.
+
+## Breadboard layout for the project
+
+There are a number of parts in this project so efficient space utilization will be important.
+The MCP3008 ADC is needed to interface the analog signal components to the Raspberry Pi digital pins.
+The analog parts are the potentiometer.
+
+The buzzer is an active buzzer with a built in oscillator and it requires a digital pin to be
+either HIGH to turn on the buzzer or LOW to turn off the buzzer.
+