My aim for this project
To construct the alarm clock I had to investigate two factors, how bright the seven-segment display would be and how loud the alarm would sound. To find out the brightness of the seven-segment display I used a light level meter and placed the blackout tube over a powered seven-segment display, the light level meter read 0. 80 lux. To find out how loud the alarm would be I used a sound detector, my mobile and a meter ruler. I placed the sound detector one meter away from my mobile; the volume of my mobile was set to its highest, the sound meter read 87 DB.
This is a reasonable sound level and I would like my alarm to sound somewhere near this number. I had very little experience with micro controllers, so to get to grips with the coding and wiring up of the micro controller I decided to make something similar to how I would make the Alarm Clock but much simpler like making one seven segment display count from 0 to 9. Below is the pin out for the circuit. I got the pin out for the micro controller Atmel (AT90S8515) from the web site http://www.
atmel. com/atmel/acrobat/0841s. pdf this gave me the pin out and the addresses for the ports and data direction registers. I also found out that the micro controller works from a power supply of 2. 7V – 6V. For the pin out for 7447 Seven Segment Decoder and the pin out for Seven Segment Display I used the back page of the AS student support book provided by the college. I powered up the circuit to test if the seven segment displays counted from 0 to 59 and repeat. It worked.
I made the seven segment displays count fast on purpose so I wouldn’t have to wait an whole hour to see if it counted from 0 to 59 and start over again. I will change the delay later on in the project. I am now going to connect two more seven segment displays and 7447 seven-segment decoders to port C of the micro controller. Port A will be connected to the two seven segment displays that will represent the hours and port C will be connected to the two seven segment displays that will represent the minutes.