phone home presentation
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PHONE HOME
By: Mark Chan, Ricky Luo, MichaelHwang
Date: December 3, 2004
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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
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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
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Phone Home Device
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Phone Line-DTMF Interface
Ring Detector Counter
Comparator(5 counts)Reed
RelayPick-Up Resistor
(120 Ω)
Phone Line
DTMF4-BitDTMF
Data Out
(-) (+)
System Reset
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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
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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.
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DTMF Matrix
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Connected Phone Line - Static
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Phone Line with DTMF SignalButton 4 (697 Hz and 1209 Hz)
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DTMF Circuit
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7 8
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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
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3.57 MHz Crystal Oscillator Output
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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)
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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
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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
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Logic Processor III
4-BitCounterCombinational
Logic
Select bits fromComparator
UP
DOWN
Difference
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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
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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.
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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
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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
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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’
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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
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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)
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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
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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.
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Recommendations
Use microcontroller to implement statemachine and logic processor
Incorporate security features into device
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QUESTIONS?