The objective of this demo is to show how the integrated resistors in the operational
amplifiers can be used to implement dynamic gain control. For simplicity in the
demonstration, only the gain of 1 (Low Gain) and the gain of 2 (High Gain) are used.
When the input signal is below 2V, the microcontroller uses the low-gain OPAMP
configuration to maximize the signal resolution and match the discrete OP AMP. Above 2V,
the microcontroller switches to the high-gain setting to increase the dynamic range
available to the system.
Figure 1-1. Simplified Block Diagram of the
System
For simplicity, only two gain settings are used in this demonstration; however, the
microcontroller supports eight selectable gain levels in addition to another unity gain
(1x). The measured voltage of both systems is displayed visually on an LED bar graph
driven by two 16-bit I/O expanders (MCP23017). Figure 1-2. Finished Demo
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