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Project Update 2
Project Update 2
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 speech recognition and voice response,
heat and other sensors for monitoring toast quality, and automated bread
platform. The user may select toast quality from voice commands stored
in the toaster's memory.
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. In an
external logic box 1 will be a microcontroller that
will process the sensor input and generate appropriate responses.
Sensors include a motion sensor to detect a toast-hungry person; visible
light LEDs to detect smoke, indicating burned toast; and a temperature
sensor to measure the energy transmitted to the bread while toasting.
For the user interface, there is speaker-dependent speech recognition and
voice response. This allows for several individuals to have their own
custom toast preferences set based upon their personal voice prints. The
voice response module will provide friendly feedback to the user based
upon the user's selection.
To ensure the safety of the toast connoisseur, the power lines in the
toaster are properly insulated. Additionally, to ensure the safety of
the toaster, the microcontroller will be shielded from the line current
switch by external circuitry. This is the case for the heating coil
switch (solid state relay) and motion sensor (relay).
The project is not as far along as we had hoped it would be at this
point. Some snags came up that were unexpected that caused delays of as
much as a week. We believe that we can still finish the project by the
June 7th due date, however.
About half of the issues raised in the first project update have been
resolved in these past two weeks. Here is a list of those issues:
- Voice Playback
- The voice playback circuit has been constructed and debugged on
the protoboard. Microcontroller code was written that
successfully records and plays voice clips at any address on the
voice chip. The same microcontroller ports that will be used for
the final design were used in this small program to reduce final
- Speech recognition
- A great deal of time and effort was invested into the speech
recognition circuit. The data sheets that were supplied with the
chip (Hualon's HM2007) did not have accurate information. Much
experimenting was necessary to determine the correct sequence for
commands and responses. Even more difficult was the experimenting
with the microphone circuit. Quelling the noise from the power
supply and the evaluation board was a nontrivial task.
- Proximity Sensor
- The proximity sensor used is more of an off-the-shelf part. It is
the motion sensor from a porch light fixture. There were three
reasons that this unit was used versus constructing a pyrometer
circuit from scratch. The first is that this unit was known to
work. The second is that finding parts for a motion sensor (i.e.,
finding the pyrometer) is not easy. The third reasons is that
this sensor has an RF transmitter and receiver. This allows the
motion sensor to be located some distance away from the receiver
and toaster, allowing for much easier placement.
- Modular Design
- One of the design issues we faced early on was the interconnection
of our external logic box to the toaster and its sensors and
actuators. We wanted to have a reliable connection between the
two units but maintain a modular design. The solution was to
implement a quick release toaster cover and a socket on the
external logic box. The socket strip allowed for the sensor and
actuator connections to be made quickly and reliably. We also
have a self-coupling motor mount in the toaster. This allows the
motor to be mounted in the external logic box and have just the
worm gear protrude into the motor.
We wish there were no major issues still pending, and that we could see
nothing but clear sailing from here on in, but that's not the case.
There are still some components that have not been tested or experimented
with. Fortunately, these components are not as inherently complex as the
voice response or speech recognition systems, so experimenting with them
should be relatively easy.
- Heat Sensor
- No experimenting has been done with the heat sensor yet.
- Bread Sensor
- No experimenting has been done with the bread sensor yet.
- Smoke Sensor
- No experimenting has been done with the smoke sensor yet.
- Bread Platform Actuator
- We have obtained a suitable motor with a 5" screw gear to be used
to raise and lower the toaster's bread tray. However, the motor
was purchased as salvage, so there is no documentation for it. We
have contacted the manufacturer, but their documentation has not
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 increase the
robustness of the entire unit.
There are four major stages of this project. These stages were detailed
in the first project update. Below is their current status.
- Voice Interface System (VIS)
- The VIS consists of the voice playback module and the speech
recognition module. Experiments have been conducted on each
module individually. Version 1.0 of the Toaster Operating System
(TOS) is currently being debugged, in which these two modules have
been combined into the one VIS.
- Sensors and Devices System (SDS)
- The SDS includes all the sensors and actuators in the project. So
far, the only sensor tested and implemented is the proximity
sensor. The actuator (the bread platform motor assembly) is in
the process of being implemented. The motor will be mounted in
the external case and the worm gear will protrude into the
toaster. The remaining sensors will be installed in the toaster
before they are fully tested. If need be, the sensors will be
- Toaster Operating System (TOS)
- The TOS is the microcontroller code that unifies the several
modules of the toaster. The present version of TOS (v1.0)
includes code for the speech recognition and voice response
systems, as well as a rudimentary flow of logic that will control
the entire toaster.
- Debugging the design
- The debugging process is an ongoing task. In particular, however,
it is more evident in the implementation of the TOS
microcontroller code. Even though the code used by TOS has been
tested individually by the modules of the VIS, the code as a whole
needs debugging to make it all work well together.
Initial Design Schematics
High level design schematic.
Speech Recognition Module schematic
Voice Response Module schematic
TOS Flowchart v1.0
The logic box is a metal box with the same footprint as the
toaster. All circuitry will be housed in this box to protect the
circuitry from the extreme temperatures of the toaster's heating
Corin Anderson |
Last modified: September 8, 1996