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Project Update 1
Project Update 1
Corin Anderson & Chris Setter
CSE 477, Spring 1996
Our project is to design and build a toaster for the Computer Scientist.
It's main features will include a voice response system, heat and other
sensors for monitoring toast making, and self-actuating bread platform.
The user may easily select toast quality from a control panel, and can be
assured of a correctly prepared slice every time.
On first glance, the toaster will look like a toaster of the classic
1950's era, complete with polished aluminum sides and traditional toasting
lever. Inside, however, is a completely different story. Internal to the
toaster will be a microcontroller that will process the sensor input and
generate appropriate responses.
Sensors will include ToastHungryPerson proximity sensing,
BurntToastCondition detection, and HeatAbsorption measuring. As for user
interface, there will be speech recognition and voice response. Further,
the speech recognition will be speaker-dependent, so toast can be made
custom to multiple users.
To ensure the safety of the ToastHungryPerson, the toaster will be built
to properly insulate the line current that is used by the heating coils.
Additionally, to ensure the safety of the toaster, the microcontroller
will be shielded from the line current switch by external circuitry, such
as a transistor.
With the exception of a few sensors, all the major
components of our project have been acquired. The most costly components
are the voice playback IC ($15), voice recognition IC ($32), power relay
($15), and microcontroller ($25). An estimate on the total cost of the
project would be $100.
Our design lends itself easily to modularity. Each major component of the
toaster is its own module, and can be tested independently of all other
modules. Below is a list of the modules in the toaster and experiments to
learn more about each. The schedule for these experiments is listed in
- Voice Playback
- The voice playback module is based on the ISD1000A sound chip. This
chip is a standard part used by many CSE 477 projects in this and
past quarters, so the design is well known. To test this design,
we will implement the circuit described in the ISD1000A's
literature. This test circuit will also serve as a platform for
recording our voice responses for the toaster.
- Voice Recognition
- The voice recognition module is designed around the HM2007 speech
recognition chip. Like the voice playback circuit, a test circuit
will be breadboarded for the voice recognition module. Unlike the
voice playback circuit, however, our project is the first project
to use a speech recognition chip, so we cannot rely on past
experience to help guide us. Fortunately, the documentation that
came with the chip, although not always as lucid as it could be,
does provide adequate diagrams and a sample circuit that can be
used as the basis for the recognition module.
- Heat Sensor
- The heat sensor we have selected is an Analog Devices 590JH. It can
withstand temperatures up to 300°F. With this constraint in
mind, we will conduct several tests to determine the best mounting
place for this sensor. There is a balance between keeping the
sensor within its heat tolerance and placing the sensor where it
can be most reliable. Using a thermocouple, we will measure the
heat produced by the toaster at various locations to determine the
- Proximity Sensor
- To detect the presence of Toast-Hungry person, we will use a
pyrometer. The pyrometer is one of the components that has not
been acquired yet, but will be in the next week. Once the sensor
has been obtained, a small circuit will be constructed to determine
the behavior of the device.
- Bread Sensor
- There are a few possible methods for detecting bread in the toaster.
One is to use an LED emitter and detector pair. The beam of light
would be broken by the toast. The advantage with this system is
reliability. The disadvantage is that the LEDs may not be able to
withstand the extreme heat of the toaster.
Another method is to use two photoresistors, one inside the
toaster, one outside. The interior detector would detect how much
ambient light from the room is trickling into the toaster. When
bread is in the toaster, the ambient light would be blocked. The
exterior detector would determine how much light is in the room to
begin with. That is, if the lights in the room are turned off,
there won't be any light in the toaster, with or without bread.
The advantage of this system is that the photoresistors may be
placed farther from the heating coils and bread than the LEDs would
- Smoke Sensor
- To detect smoke in the toaster, a matched emitter-detector pair
of LEDs will be used. We will be conducting tests on this
system to determine if the LEDs can withstand the heat
produced by the toaster.
Construction and Debugging Plan
All the electronics for the toaster will be housed in a case underneath
the toaster. The controlling logic will interface to the toaster and its
sensors through a modular plug so the toaster and case may be separated.
This will ease the debugging of the design as well as the robustness of
the entire unit.
There are four major stages of this project. As specified, they may be
implemented in parallel between Chris and Corey. The stages are:
- Voice Interface System (VIS)
- The VIS consists of the voice playback module and the voice
recognition module. After the experiments for these modules, they
will be assembled onto either wirewrap or solder boards. Modular
plugs will be included so the microphone and speaker may be
attached later. Easy access to the control, data, and address
lines will also be included to ease debugging in the final design.
The VIS will be mounted inside the case.
- Sensor and Devices System (SDS)
- The SDS includes all the sensors and actuators in the project.
After experiments are conducted with each sensor and actuator, the
device can be mounted inside the toaster. Wires will be placed
carefully in the toaster to reduce heat effects from the toasting
- Toaster Operating System (TOS)
- The TOS will be developed concurrently with the experimentation of
the modules. As code is debugged for each module, it will be added
to the operating system of the toaster. When the experimentation
is finished, the TOS should be mostly complete as well.
- Debugging the design
- It would be foolish to claim that the toaster will work properly
from the start. As such, we will provide debugging hooks in both
the software and in the hardware implementation. In software, we
will take care to document the system as we develop it. This
document can serve as a road map for debugging the microcontroller
code. On the hardware side, easy access to control, address, and
data lines will be provided. These signals will be labeled in the
circuit so that they may be easily traced.
Initial Design Schematics
High level design schematic.
Division of Labor and Schedule
The tasks of the project lend themselves to parallelization without much
difficulty. The following table summarizes the activities we each will be
doing in the upcoming few weeks.
|Experiment with voice playback circuit. Begin experimenting with
voice recognition chip.
||Clean up toaster.
|Conclude experiments with voice recognition chip. Begin laying
out microcontroller code for TOS. Begin experimenting with
||Experiment and install heat sensor. Experiment and begin
implementing a bread platform mechanism. Determine which smoke
and bread sensors we will use.
|Do final assembly of VIS on wirewrap or solder board. Continue
writing TOS. Record voice responses for toaster. Finish
experimenting with proximity sensor.
||Experiment and mount bread and smoke sensors. Determine interface
method between toaster and electronics case. Finalize
implementation for bread platform. Merge sensor input code with
|Mount proximity sensor. Help Chris with sensor mounting in
toaster. General debugging.
||Mount power supply and heating coil switch. General toaster
|Write final report, hope that nothing breaks.
||Write final report, hope that nothing breaks.
Corin Anderson |
Last modified: September 8, 1996