A 15kg weighing scale was designed using Microchip's TC500A
Analog Processor and the TC520 16-bit Controller. The scale is
required to resolve down to 1/8 gram and correct to within 61/2
gram. This project takes into account all aspects of a functional scale:
• Dynamic Range
• Strain Gauge Compensation
• Zeroing
• Oversampling
• Units Conversion (kilograms to pounds)
The TC500A is an analog processor device which performs a dual-
slope analog-to-digital conversion function. All of the counting and
timing for the conversion must be controlled by an external source.
In nearly all applications, this control source is a microprocessor.
The microprocessor is programmed to monitor the status and to
control the timing of the TC500A. It must also be programmed to
count the conversion results. AN780
15-Kilogram Scale Using the TC500A and the TC520
The TC500A has no agenda of its own so it can be used to generate
Author: Ted Dabney,
slow, high resolution conversions or fast, low resolution conver-
Microchip Technology, Inc.
sions. The trade-off for accuracy is about 1000 counts per millisec-
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