Speech Synthesized Temperature Sensor Denise Kittrell
This device informs the user of the current temperature in degrees Fahrenheit by a synthesized speech message.
Performance • Range must span 60 degrees • Resolution must be 1 degree • Speaker output must be clear • Coherent Speech Message • Device Must operate in various temperatures
Inspiration for This Project • High temperature alert device for vehicles • Aid to the visually impaired • Convenient in Laboratory Settings
Type one is a high temperature alert system. This system only requires storage of one speech message. Type two is the original Speech Synthesized Temperature Sensor Due to the memory requirements of this device an upgrade from the 16F84 to the 16F873 was made. Two Types of Designs Depending upon the Application
The BASIC command sound can replace the SPO-256 User may select desired Temperature threshold through button interface. Compact Size Low Cost User defined temperature threshold Volume Control Remarks and Benefits
Remarks • The PIC16F873 has an onboard A/D converter. • Speech Synthesizers come in two main types. • Ones that use sampled speech • Ones using allophones which are electronic phonemes PROS/CONS
Example Intriguing = IH NN1 PA3 TT2 RR2 IY PA1 GG3 IH NG More art than engineering or maybe this is just the art of engineering?
Subroutines Inside Loop • Subroutine that stores the eight lower bits from DS1620 output into an output register. • Subroutine that shifts 9 bits of input into lsbs of an input register • Subroutine that converts scale to Fahrenheit
A/D Converter Module for PIC16F873 ADCON0 • A/D conversion CLK • Fosc/8 for 4MHz Clock • 12 bit time • 24us total conversion time • Analog Channel Selection • Conversion Status bit ADON
ADCON1 • Configures Vref+ and Vref- • Analog Input Channels • One Analog Channel is required and Vref+=Vdd and Vref-=Vcc
A/D Code Outline for 16F873 • Initialize ADCON0 and ADCON1 • Wait 20us for internal capacitor at input to charge • Select A/D conversion CLK • Turn on A/D module
Outline Continued • Select A/D input channel • Configure input channel • Set GO bit • Wait 24us for GO to clear • Read result from ADRESH and ADRESL
Design Challenges • PIC16F84 has only 1k of program memory • Difficulty maintaining stable Vref+ for TLC549 • Determining which allophones should be concatenated to produce clear message
Old Code Improved Code 13 messages 1136 words 52 messages 2657 words 15 messages 2324 words 72 messages 3560 words 1 message 594 Words 1 message 45 words Memory Issues
Possible Extensions • Other types of sensors may be added to extend the functionality of this device. • The data could also be displayed on an LCD screen. • Remote communication system