phone home presentation

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PHONE HOME

By: Mark Chan, Ricky Luo, MichaelHwang

Date: December 3, 2004



Phone Home

Machine allowing user to control thethermostat at home via telephone

Provide comfort and convenience

Can be further integrated into controllingvarious functions within the home (remotelighting, door locks, etc)

Passcode protected to prevent intrusion



Phone Home

Objective: to access and to control a homethermostat with a local phone line from aremote phone connection using TTL

hardware

Scope: remote controlling of thermostat



Phone Home Device



Phone Line-DTMF Interface

Ring Detector Counter

Comparator(5 counts)Reed

RelayPick-Up Resistor

(120 Ω)

Phone Line

DTMF4-BitDTMF

Data Out

(-) (+)

System Reset



US Phone Line and DTMF Signal

US Line: 6 to 12 V35 mA

US Ring: 40 to 150 V35 mA15-68 Hz

Lab Phone: 85.5 V

35 mA20 Hz



Ring Detector

The Ring Detector will take the 40 to 150 V AC ring signal ofthe phone line and output a 5.6 V DC pulse for the duration ofeach ring.

The output of the Ring Detector will be used to drive thecounter in our pick-up and hang-up circuit.

Built-in lightning protection: 1.5 kV of 200 μ s maxduration

Additional Filtering: 0.47 μF and 2.2 k Ω in series to (+)phone line (red)

Note: The TCM1520A Ring Detector used in our circuitwas the most difficult IC to acquire.



DTMF Matrix



Connected Phone Line - Static



Phone Line with DTMF SignalButton 4 (697 Hz and 1209 Hz)



DTMF Circuit

1

2

3

4

5

6

7 8

9

10

11

12

13

14

D T M F

Crystal 3.57 MHz1 MOhm

0

Data 0

Data 1

Data 2

Data 3

Strobe

0.1 uFVDD

D1

D2

D4

D8

ENB

VDD

GT

Xen

Ain GND

Xout

Xin

ATB

DV

0.01 uF

1500 pF33 kOhm

Phone Line (+)

Phone Line (-)

AC Coupling Circuit



3.57 MHz Crystal Oscillator Output



Logic Processor:Overview

Inputs: 1) Outputs from DTMF in BCD2) Current temperature in Binary3) State machine signals (e.g. clock 10 Hz, select

bits, counter signals)

Outputs: 1) Up and down signals2) Heat, cool, and off signals3) State machine signals (e.g. validity

bit)



Z e r o C h e c k e r

C i r c ui t

S

# / * / 0

M S B

L S B

BCD to binary

Converter

BCDfromDTMF

0000

New Temp in Binary

RegistersMux

Logic Processor I



Logic Processor II

S

S

Comparator Array

Subtractor New Temp

New Temp

Current Temp

Current Temp

New Temp

D

i f f e r e n c e

Register

To counter



Logic Processor III

4-BitCounterCombinational

Logic

Select bits fromComparator

UP

DOWN

Difference



State MachineMealy vs. Moore

Mealy: Outputs depend upon current state andinputs

Advantage: Usually involves less logic Disadvantage: Asynchronous, unless additional

complicated logic is included

Moore: Outputs are solely dependant upon currentstate

Advantages: Synchronous More compatible with TTL Easier to manage and debug Disadvantages: Usually involves more logic Usually requires more states



Signals - Inputs (to state machine)

RC: Ring Count; this signals is highwhen five rings have been counted.

SC (0:1): Strobe Count; bus of two wiresrepresenting the number of buttonspushed.

TC: Terminal Count; signifies that theappropriate number ofincrements/decrements have beenmade. This signal is high after the

down counter has reached zero.Delay End: Signifies the end of a delay determined

by a counter. Essential the terminalcount of the delay counter.



State MachineOutputs

P/H DTMF IR0 IR1 IR2 TR FR

COUNTER DEL AY

State Gray Code RR RCR SCR S S S S S PE CE TCE PE

0 Stand-by 000 0 1 0 0 0 0 1 1 1 1 0 0

1 0-Button 001 1 1 1 1 0 0 1 1 1 1 0 0

2 1-Button 011 1 1 1 0 1 0 1 1 1 1 0 0

3 2-Button 010 1 1 1 0 0 1 0 1 1 1 0 0

4 3-Button 110 1 0 1 0 0 0 0 1 1 1 0 0

5 TCE 111 1 1 1 0 0 0 0 0 0 X 1 1

6 Set-Temp 101 0 1 1 0 0 0 0 0 1 0 0 1

7 Finish 100 0 1 1 0 0 0 0 0 1 1 0 0



State MachineState Diagram

000Stand

-By

0010-

Button

0111-

Button

0102-

Button

100Finish 101SetTemp

111TCE 1103-Butto

n

RESET

1 XX XX

1 01 XX

1 10 XX

1 11 XX

X XX XX

X XX X1

X XX 1X

X XX XX

RC, SC1, SC0, TC, Delay End



State MachineBoolean logic of the State Machine (Outputs)

Eight states = three flip flops, C, B, and A

RR = C’B’A’ + CB’A + CB’A’

RCR = CBA’

SCR = C + B + A

IR0 = C’B’A

IR1 = C’BA

IR2 = C’BA’



State MachineBoolean logic of the State Machine (Outputs)

TR = C’B’A’ + C’B’A + C’BA

FR = (C’ + B’ + A’)(C’ + B + A’)(C’ + B + A)

Count(PE) = CBA

Count(CE ) = CB’A

Delay(PE ) = CBA + CB’A

TCE = CBA



State MachineBoolean logic of the State Machine (state F/Fvalues)

A+ = (C’B’A’*RC) + (C’B’A*SC1’*SC0) +(CBA’*DelayEnd) + (CBA*TC)

B+ = (C’B’A*SC1’*SC0) +

(C’BA*SC1*SC0’) + (C’BA’*SC1*SC0) +(CBA’*DelayEnd)

C+ = (C’BA’*SC1*SC0) + (CBA’*DelayEnd) +(CBA*TC) + (CB’A)



DTMF Problems

Unsuccessful in capturing DTMF signal

Signal from phone line not perfect – static frequencyInconsistency among individual phone linesNumerous AC coupling setups attempted unsuccessfullyMC145436 failed to recognize valid DTMF signal

Solution

More research in a better AC coupling circuit for MC145436Replace MC145436 with more popular and more powerfulMitel MT8870



State MachineProblems

Fan out: One output fanning out to 15pins.

Solution: Use buffers/drivers to increase the

signal voltage.

Complexity: Design is not verycomplicated, however, 100+wires are hard to manage andkeep track of.

Solution: Use microprocessor, VHDL or otherVLSI microprocessor.



Recommendations

Use microcontroller to implement statemachine and logic processor

Incorporate security features into device



QUESTIONS?

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