V-Scan Signal Digitizer Technical Requirements

V-Scan Technical Requirements

The variation of the signal to be measured is in the range of 0 to 200µV (as a baseline). This is the primary factor to consider at this stage to provide a digitizer capable of recording the minimum difference (approximately 5µV theoretical data).

Signal Measurement and Amplification

Based on the requirements, the following conditions must be met:

• The amplification circuit must provide a gain factor of more than 1000 items of amplification.
• The scanning circuit must be able to record such variations.

Microcontroller Selection Criteria

To achieve this scanning, we propose a microcontroller with the following characteristics:

• Analog/Digital Converter (ADC): Equipped with the necessary resolution.
• Channel Count: Sufficient to enable the reception of at least 2 channels, as required by our dual-channel bio-acquisition module.
• Processing Speed: Power required for digitization without affecting or reducing performance.
• Communication Interface: Robust connectivity options.

Communication Interface Protocols

This type of PIC offers various communication protocols, such as:

• SPI and I2C: Serial communication protocols used primarily for communication between peripheral devices or microcontrollers.
• USART: Mainly used for asynchronous transmit-receive protocols such as RS-232.
• USB: A serial interface for data transmission and power distribution. It has been introduced into PCs and peripherals to enhance slow serial (RS-232) and parallel interfaces. It provides faster transfer rates (up to 100 times faster) compared to parallel ports and 9-pin or 25-pin serial ports found in most computers.

Our chosen method for information transfer is USB, considering the advantages and possibilities that the interface provides.

USB Information Transfer Specifications

As defined previously, the transfer of information has been designed using a USB interface.

This 4-wire interface uses 5V to distribute power and can transmit data at speeds up to 480 Mbps in version 2.0. It is a serial bus that allows the connection of up to 127 peripherals to a single port of a PC with automatic detection and configuration. This is possible with the PC connected to the network without installing additional software and without restarting the computer (Plug and Play), which conventional serial and parallel ports do not support. Furthermore, there is no need to worry about IRQ conflicts or installing adapter cards for each peripheral.

Once the communication interface is set, we must review its technical specifications to attach the Digitizer Module for electroencephalographic signals.