Version 1.0

Author: gavinlyonsrepo

README.md

@@ -5,9 +5,16 @@ Overview
 * Title: Micro-controller Countdown Timer
 * Description: Countdown Timer: Range 1-99 minutes. 
 Output time (mm:ss) to seven segment display and Audio to Buzzer.
-Input: Push button to start.  10K Pot used for time select.
+Input: Push button to start.  Potentiometer  used for time select.
 * Author: Gavin Lyons
 
+
+libraries 
+--------------------
+
+None
+
+
 Software Used
 ------------------
 Arduino 1.8.5
@@ -26,15 +33,15 @@ You will need following parts.
 >
 > Resistors: 20 ohms , 220 ohms, 660 ohms, 10K
 >
-> 4 digit seven segment module
+> 4 digit seven segment module  (SMA420564)
 >
-> one 10 k potentiometer 
+> one 50 k potentiometer 
 >
 > one pushbutton
 >
 > One on/off SPST switches
 >
-> One piezo buzzer
+> One piezo buzzer passive
 >
 > One 16 Mhz crystal
 >
@@ -44,14 +51,41 @@ You will need following parts.
 >
 
 Features
-----------------------
-The user selects the countdown time (1-99 minutes) with the potentiometer  then starts with the pushbutton.
-Time remaining is displayed on seven segment display. When finished the buzzer is activated and done displayed on 4 digit 7-segment display.
+------------------------
+The user selects the countdown time (1-99 minutes) with the potentiometer then starts with the pushbutton.
+Time remaining is displayed on seven segment display. When finished the buzzer is activated and Zero displayed on 4 digit 7-segment display for a few minutes, The unit then shuts off  display and buzzer.
 
-![ScreenShot schematic one ](https://github.com/gavinlyonsrepo/timer_arduino_two/blob/master/documentation/eagle/timer_arduino_two.jpg)
 
+LED Array Pin Layout
 
+| Pin Uno | Pin Atmega  | 7 Segment pin  |   
+| --- | --- | --- | --- |
+|  D2 |  PD2 | a  |  
+|  D3 |  PD3 | b  |   
+|  D4  | PD4  | c  |    
+|  D5 |  PD5 |  d |   
+| D6  |  PD6 |  e |     
+|  D7 |  PD7 | f  |  
+| D8  | PB0  |  g |     
+|  n/c |  n/c | p |       
+| D10  | PB2  |  d4 |   
+| D11  | PB3  |  d3 |   
+| D12  | PB4  |  d2 |  
+| D13  | PB5  |  d1 |     
 
+
+The 4-digit seven segment display (SMA420564 or SM420564) is a common-cathode display.  
+4 Digit 7 Segment Cathode Red LED Display 0.56" SM420564. 
+
+![ScreenShot seven segment ](https://github.com/gavinlyonsrepo/timer_arduino_two/blob/master/documentation/image/7segpinout.png)
+ 
+ 
+Schematic
+---------------- 
+
+![ScreenShot schematic one ](https://github.com/gavinlyonsrepo/timer_arduino_two/blob/master/documentation/eagle/timer_two_arduino.png)
+
+
 Copyright
 ---------
 Copyright (C) 2018 Gavin Lyons