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© 2005 Microchip Technology Inc. DS00981A-page 1
AN981
INTRODUCTION
Analog output silicon temperature sensors offer an
easy-to-use alternative to traditional temperature
sensors, such as thermistors. The MCP9700 offers
many system-level advantages, including the integra-
tion of the temperature sensor and signal-conditioning
circuitry on a single chip. Analog output sensors are
especially suited for embedded systems due to their
linear output. This application note will discuss system
integration, firmware implementation and PCB layout
techniques for using the MCP9700 in an embedded
system.
The firmware required to interface the MCP9700 to a
microcontroller will be demonstrated using the
PICkit
™ 1 Flash Starter Kit. The PICkit 1 Flash Starter
Kit is a low-cost development kit with an easy-to-use
interface for programming Microchip’s 8-pin and 14-pin
Flash family of microcontrollers.
The MCP9700 demonstration is designed to measure
and display temperature in Binary-Coded Decimal
(BCD) with the PICkit 1 Flash Starter Kit’s LEDs.
Temperature data is converted from the internal ther-
mal sensing element and made available as an analog
output voltage. Gerber files for the PCB, source code
and hex file (to program a PIC16F676) are included in
the companion zip file, 00059R1.zip.
FIGURE 1: Block Diagram of the MCP9700 Thermal Sensor Demonstration.
Author: Ezana Haile and Jim Lepkowski
Microchip Technology Inc.
MCP9700
V
DD
PICmicro®
Flash
MCP9700 PICtail™
ADC
GND
Temperature
Sensor
MCU
PICkit™ 1 Flash Starter Kit
Daughter Board
Personal
USB
LED Array
D0D1D2D3
D4D5D6D7
J3
+5V
P1
V
OUT
Tens Digit
Ones Digit
Temperature Data
Computer
Interfacing a MCP9700 Analog Output Temperature Sensor
to a PICmicro
®
Microcontroller
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