DEVICE CONTROL Through A PC's USB Port Using Visual Basic

This Windows-based program, created with Microsoft Visual Basic (VB6), features an intuitive user graphic interface (UGI) and operates seamlessly on the Windows platform.

- Adeeb Raza

It interfaces with a personal computer's (PC's) USB port via a hardware module, which includes a microprocessor-based electronic circuit capable of controlling up to eight appliances through the PC.

The program transmits specific instructions to the microprocessor-based interface card via the USB port. These instructions are pre-programmed and stored in the microprocessor's memory. Actions are executed through a designated relay number linked to an input/output (I/O) pin of the microprocessor and driver circuit.

At its core is the ATmega328P, a single-chip, 8-bit microcontroller housed in a 28-pin DIL package.

This microcontroller is both cost-effective and widely available in the Indian market. As it is the same IC used in Arduino Uno, the ATmega328P circuit can be easily replaced with an Arduino Uno board, if preferred.

The Arduino IDE, required to program the ATmega328P, is available for free download at https:// www.arduino.cc/en/software. A block diagram illustrating the program's functionality is shown in Fig. 1, while the complete bill of materials is provided in the table on this page.

This program involves using Visual Basic (VB) to communicate with an external hardware module through the USB port.

A basic understanding of VB programming and hardware knowledge for connecting and controlling the hardware module is necessary. A microcontroller or USB interface module acts as the intermediary between the PC and the appliances.

The appliances are connected via relays. A general-purpose PCB or breadboard, jumper wires, and a power supply for external appliances are used. Fig. 2 shows the USB-to-TTL serial converter used to program the microcontroller ATmega328P.

Circuit and working