User manual

MCP3421 WEIGHT SCALE
DEMO BOARD USER’S GUIDE
 2010 Microchip Technology Inc. DS51918A-page 9
Chapter 1. Product Overview
1.1 OVERVIEW
The MCP3421 Weight Scale Demo Board works with the LabVIEW™ Graphical User
Interface (GUI) PC Software. This demo board demonstrates how to use the MCP3421
18-bit Delta-Sigma ADC for weight scale applications. It uses the PIC18F4550 micro-
controller for data processing and USB communication with PC. This board also dem-
onstrates the changes in the system performance by adjusting the parameters of the
sensor signal conditioning circuits using the MCP6V07 auto-zeroed op amp.
1.1.1 Feature Highlights
• The LCD displays the user’s selected option and the ADC output code or the
calculated results.
• The user can select the signal averaging factor (1 or 4) by pressing the S3 button.
The selected option is displayed on the LCD.
• System performance analysis using PC GUI: the interface allows various
interactive post signal processing, such as standard deviations and histogram.
• Hardware PCB design examples: this demo board utilizes a robust grounding
method of analog circuits in PCB design. It also demonstrates how to split analog
and digital ground planes.
• Signal conditioning examples using MCP6V07: the low-noise op amp is used to
boost input signal levels.
• 2 Kg load cell with 1 mV/V sensitivity.
FIGURE 1-1: MCP3421 Weight Scale Demo Board.