Construction and testing
An actual-size, single-side PCB for real-time clock including the power supply section is shown in Fig. 3 and its component layout in Fig. 4. Assemble the circuit on a PCB to minimise assembly errors and save time. Carefully assemble the components and double-check for any overlooked error. Use proper IC base for the microcontroller. Before inserting the ICs, check all the supply voltages.
To verify the circuit for proper functioning, check correct power supply at test point TP1 with respect to TP0. Reset signal for the microcontroller can be verified at TP2. Check the display-enable signal at TP3 through TP6 for corresponding display.
Software for the real-time clock is written in ‘C’ language and compiled using the Keil µVision4 compiler. The generated hex code is burnt into the microcontroller by using a suitable programmer. All the switches are regularly scanned. When any switch goes low, corresponding action is performed and displayed.
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The author is incharge head, department of Physics and Electronics, Hem. North Gujarat University, Patan