1. Problem 1 Choose title 1 st XML 2 nd electronic spider 3 rd infrared remote home control Waste time

2. Problem 2 Write Program Added Delay subroutine Added Table Loop Delay execution time Not necessary

3. Test Result Input (dual-tone signal)Output (89C51 port1 LEDs) pin8 to pin1 000001111 100000010 200000100 300001000 400010000 500100000 601000000 710000000 811111111 900000000 000001111 0-off 1-on

4. Problem 3 LEDs unstable Use resistor connect 5V Pulled the LEDs HIGH LEDs become stable

5. Problem 4 Remove Reset button Cannot receive input signal properly Added the Reset button in 89C51 pin 9 89C51 receive signal before pressed Reset button

6. Problem 5 Test success in the breadboard Tried to connect to the board Telephone’s current breaks down the 89C51 Added a relay counter Hold the input current

7. Problem 6 MT8870 does not auto hook off on telephone Connect to 4040 & RY6WFZ-K relay to MT8870 Ringing value at 2 to power 12 Can auto hook off the phone

8. Problem 7 Voltage of ringing signal between +1.4V to –1.4V Unstable & Not enough power Connect 4040 with amplifier & transistor Pulled HIGH the voltage Rectified the current

9. Problem 8 Dual tone receive signals– Full wave rectified 4040 counter only accept – Half wave rectified Added a diode to transfer Signal become half wave rectified

10. Problem 9 Signal’s current too high 4040 Counter break down Change the 4040 counter Added a relay to prevent

11. Test Result Phone in  Phone  4040 counter auto hook off  Key pressed  Dual tone  MT8870  Binary code  89C51  LEDs Display the result

12. MT8870 & 89C51 scematic

13. MT8870 & 89C51 breadboard

14. Relay & 4040 counter schematic

15. 4040 counter & relay breadboard

16. Power supply schematic

17. Power supply board