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2. No backlight on the LCD. Check the voltage at pin 15 (+5V) and pin 16 (0V) of the LCD.

3. Page 1/page 2 is shown on the screen but the remote commander doesn’t work (nothing happens on pressing functional keys of the remote). Check the supply at pin 2 of the IR sensor. It should be +5V. If +5V is available at pin 2, check the voltage at pin 3 of the IR sensor. If there is no voltage at pin 3, replace the IR sensor or check the PCB, etc for shorting.

Once the LCD shows page-1 and page-2 text properly and the remote commander is working, switch off the power and then switch it on again using S1. Now the LCD should show page-1 and page-2 as shown in Fig. 3. At the same time, pin 14 of the MCU should go high (+5V) and the power standby LED should glow. Now press ‘Power’ key on the remote. Pin 14 of the MCU should go low and the standby LED should turn off, and vice versa, on pressing the same key again. If this doesn’t happen, replace the microcontroller.

Connect LED1 through LED6 to connector CON1. Press ‘Power’ key on the remote to switch on the switcher. Page-3 text should appear on the LCD, showing camera-1 is ‘on,’ the switcher is in manual mode and the default time of camera hold for auto mode. At the same time, Port-C pin RC7 should go high and LED1 should glow. Select other cameras either by pressing keys 1 through 6 or camera up/down keys of the remote and check whether the corresponding LEDs (LED1 through LED6) are glowing (refer to Port-C truth table). Simultaneously, page-3 should show the corresponding camera number accordingly. If the LEDs don’t glow according to the truth table, replace the microcontroller.

When camera-1 is selected, the LCD should show camera-1 and LED1 should glow. If the monitor does not show the video of camera-1, or you hear no audio from the power amplifier, check 5V logic at pins 5 and 6 of IC4. If there is no voltage at these pins, check the availability of 0.6V at the base of transistor T5, +5V at its emitter and +12V at its collector. Follow the same procedure for all other cameras and their corresponding switching circuits.

Software

The source program is written in Assembly language and compiled using MPASM tool suite.

Construction

A single-side, solder-side PCB layout for the microcontroller-based remote controlled six-camera CCTV switcher and its component layout is given below for download.

Connect CCTV cameras in the sockets provided (SK1 through SK6). Also connect the LCD and remaining components (as shown in Fig.2) and +5V and +12V from the power supply circuit. Now a welcome message will appear. Press ‘Power’ key on the remote to start the switcher.

EFY note. The source code is available on the link given below.

Download PCB and component layout PDFs: click here

Download source code: click here

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