Transcript 563 kB PowerPoint

COMPUCCINO
Kalani Rathnabharathi
Vithya Shanmugam
Robert Armstrong
Aaron Kulp
Power Supply
 Converts 110VAC to 12VDC & 5VDC
 Components:
– 5:1 Transformer
• Converts 110VAC to 22VAC
– Full-Wave Rectifier Bridge
• Rectifies the AC voltage
– UA7812 Regulator
• Smoothes out the ripples and give
12VDC
– UA7805 Regulator
• Converts 12VDC to 5VDC
– LED Indicators
 Diodes on regulators prevent backflow
of current through the regulators
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8051 Processor
 The core of our local embedded system will
be an 8051 processor in tandem with an
XC2S100 FPGA
 The primary function of this processor will
be to monitor and control the sensors and
features of the coffee pot
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Embedded Peripherals
 8051 platform has the following on-board
peripherals:
–
–
–
–
–
I2C EEPROM
MAX118 A/D Converter
DS1302 Real-Time Clock
MAX232 for RS-232 level conversion
20x4 Character LCD
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Memory Map
 To enable the use of a
monitor/debug
program, we have
combined the memory
map into one 64K
block
 If more than 32k of
code is necessary, we
can split the map into
RAM/ROM
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Main Program Outline
“Pseudo” Code:
Main()
{
Initialize timers;
Initialize interrupts;
Initialize serial I/O;
Initialize peripherals;
for(;;)
{
Check for/respond to remote commands;
Check for/respond to local commands;
Refresh sensor data;
Redraw local user interface;
}
}
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A/D Conversion
 Over half of our sensors require analog to digital conversion, which will be
accomplished with a MAX118
 The MAX118 is an 8-bit, 8 channel 5V sigma-delta analog to digital converter
– This gives us an effective resolution of approximately 20 mV
– Any further resolution would be irrelevant in our prototype board, because signal
noise would cause fluctuations in the voltage leading to us needing to discard the
least significant bits
 In order to avoid signal timing issues and to get the greatest possible processor
bandwidth, we have configured the MAX118 to fire an interrupt when the
conversion is complete
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A/D Conversion Timing
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Water Level Sensor
 MPX4115A pressure
sensors
 Two LM358 op amps
cascaded together
 Output of 1st op amp acts
as a summing node for the
difference between
Vreference-Vmeasured
 Output of second op amp
will be:
5V –100Out1
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Water Level Design Consideration…
 Design Consideration One:
• We need an initial reference point pressure and corresponding voltage
 Design Consideration Solution One:
• We will use barometric pressure as the reference point
• By utilizing a differential op amp, we can isolate our measured water level
pressure reading from the barometric pressure, giving us the corresponding
water level
 Design Consideration Two:
• Voltages outputting from first differential op amp will be amplified by 100x.
We need to compensate for negative voltages.
 Design Consideration Solution Two:
• We will cascade two op amps together, The output of our second op amp will
be 5V-100Out1
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Water Level Test Results
 Test to determine what voltage corresponds
to particular water level
 Recorded:
Cup Size
Voltage
2
3.2186V
3
3.2216V
4
3.2301V
5
3.2334V
6
3.2367V
7
3.2406V
8
3.2443V
9
3.2479V
10
3.2516V
 Conclusion: Water Level versus Voltage is a linear relationship
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Water Quality
Water Quality Sensor-Milestone 2
ADC
5V
Resistor
Coffee
Pot
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Hot Plate Control
 Active high
control from
8051 I/O
 Relay – 12V
controlling
120VAC
 Fuse protection
at 227ºC
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Blender Control
 Active high
control from 8051
I/O
 Relay – 12V
controlling
120VAC
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Control Waveforms
Relay off
Control
Relay on
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Blender Demo
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Pot Temp Sensor
 Option1 - Voltage
divider
 Option 2 – IR sensor
 Output into an ADC
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Hot Plate Temp Sensor
 Voltage Divider
 Output into an ADC
 Thermistor –
resistance is
temperature sensitive.
 Temp range – -50ºC to
250 ºC
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Pump / Cup Size
Reservoir
Pot
Water Level
Sensor
Hot Plate
Valve
 Control valve according to
reading of water level sensor
 Mechanically controlled
valve.
 Control of pump:
– Valve opens (remains open
according to cup size)
– Water flows from reservoir to
hotplate
– Pressure build up pushes water
through grounds to pot.
 Milestone 2
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Schedule
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QUESTIONS???
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