Download Very good – all requirements aptly met. Minor additions/corrections

ECE 477
Digital Systems Senior Design Project
Fall 2007
Homework 5: Theory of Operation and Hardware Design Narrative
Due: Friday, September 28, at NOON
Team Code Name: wifiMote______________________ Group No. ___7___
Team Member Completing This Homework: _____Siddharth Gupta__
e-mail Address of Team Member: gupta5 @ purdue.edu
NOTE: This is the second in a series of four “design component” homework assignments,
each of which is to be completed by one team member. The completed homework will count
for 20% of the individual component of the team member’s grade. The body of the report
should be 3-5 pages, not including this cover page, references, attachments or appendices.
Evaluation:
SCORE
DESCRIPTION
Excellent – among the best papers submitted for this assignment. Very few
corrections needed for version submitted in Final Report.
Very good – all requirements aptly met. Minor additions/corrections needed for
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version submitted in Final Report.
Good – all requirements considered and addressed. Several noteworthy
8
additions/corrections needed for version submitted in Final Report.
Average – all requirements basically met, but some revisions in content should
7
be made for the version submitted in the Final Report.
Marginal – all requirements met at a nominal level. Significant revisions in
6
content should be made for the version submitted in the Final Report.
Below the passing threshold – major revisions required to meet report
*
requirements at a nominal level. Revise and resubmit.
* Resubmissions are due within one week of the date of return, and will be awarded a score of
“6” provided all report requirements have been met at a nominal level.
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Comments:
Comments from the grader will be inserted here
ECE 477
Digital Systems Senior Design Project
Fall 2007
1.0 Introduction
The objective of the wifiMote is to design and create a wireless hand-held television (TV)
remote. It will allow a user to “channel surf” without interfering with what is being watched on
TV. The remote will have a touch screen Liquid Crystal Display (LCD) interface that will be
capable of receiving and displaying a TV video stream. The user will be able to provide inputs
through the touch panel interface on the LCD and will be able to change the preview on the
handheld and also change the channel on the TV. The device will interface with a 2.4GHz
wireless video receiver which will receive the video stream from a TV Tuner/RF transmitter. The
remote will also be interfaced with Infrared Transmitter and Receiver. The device will run on six
AA batteries with recharging capabilities. The user would also be able to monitor the battery
status on the display. The portability of the device will be maintained since it is handheld.
2.0 Theory of Operation
2.1 LCD Interface
The touch screen LCD will have the ability to take user input. The user will be able to
change the channel being previewed on the LCD and also change the channel on the TV. The
display is 3.5 inches diagonally which provides enough space for a touch screen input. The LCD
that will be used for the device is Microtips MTF-T035DHSLP-A [2]. This LCD needs +16 V
for gate on power and -10 V for gate off power. These are the voltages needed to power the
screen. The LCD module also requires 3.3 V and 5 V as digital and analog power supplies
respectively. The LCD interfaces with the LCD controller which in turn interfaces with the
microcontroller. The display needs 24 bit data bus input, 8 bits each for RGB. However, the
LCD controller can only provide an 18 bit data bus which is R0-R5, G0-G5 and B0-B5. So the
remaining the 6 bits of the LCD input will be set to high. The LCD also takes the Hsync and the
Vsync values from the microcontroller. The LCD controller that we will use is Epson S1D13A04
[3]. It operates at 3.3 V. It takes an input voltage of 3.3 V typical and the output voltage ranges
from -0.3 to 3.8 V while the LCD takes an input voltage of -0.3 to 5.3 V, so we will not need a
RS-232 level translator. The LCD needs a 6.4 MHz clock input which will come from the LCD
controller. The clock input to the LCD controller can come from the microcontroller with the
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ECE 477
Digital Systems Senior Design Project
Fall 2007
help of a timer module. The LCD controller can take a maximum 50 MHz clock input. It also has
an SPI interface with the microcontroller for data input/output.
2.2 Power Management System
Since this is a device that will have higher power requirements compared to generic
remotes, a rechargeable interface would be required to make the remote viable. Also, since it is a
portable device, it would not make sense to power the device from a wall socket. Instead the
design being implemented is a remote which runs on rechargeable AA batteries with an adapter
for recharging the batteries.
Six AA NiMH rechargeable batteries giving 1.2 V each will be used. These batteries will
be connected in series to give a total of 7.2V output. The highest voltage requirements are from
the LCD. A voltage of 14V and -11V need to be driven from the 7.2V from the batteries. In order
to generate these voltages, a charge pump will be used which will decrease the output current.
These lines of the LCD do not draw much current (0.4 mA and 0.3 mA). So the charge pump is a
feasible option. We will also use the Dallas Semiconductor DS2715 [6] for charging the
batteries. The AC input will be regulated through a linear regulator. The two voltage inputs will
be connected to another linear regulator by steering diodes to prevent the power supply from
coming from the batteries.
2.3 Touch Panel Interface
The LCD also needs a touch panel controller to control the touch screen interface on the
LCD. The touch panel controller that we will use is TI ADS7843 [4]. It operates at 2.7 V to 5.0
V. It has a SCI (UART) interface with the microcontroller for serial data input/output. It also
provides 4 input to the LCD, 2 each for X and Y position.
2.4 RF Receiver
The RF Receiver [5] receives the composite video data at 2.4 GHz and demodulates it to be
displayed on the LCD. It has an internal crystal oscillator, so it doesn’t need any clock signal
from the microcontroller. It operates at 5 volts. It takes the radio input from a 50 ohm antenna. It
outputs the composite video signal, which is an analog signal which is 1 V P-P. The RF Receiver
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ECE 477
Digital Systems Senior Design Project
Fall 2007
will send composite video data to one ATD channel on the microcontroller. There will also be
three inputs from the microcontroller to select the RF channel that the receiver will use.
2.5 Microcontroller
The microcontroller that will be used for the device is the Microchip PIC24HJ256GP210
[1]. It will be powered at 3.3 V and will operate at 64 MHz. This clock frequency will be
controlled by an external crystal oscillator. The microcontroller will take analog input from the
2.4 GHz RF Receiver through the ATD and then the digital data which represents a single frame
would be compressed from 720x480 resolution to 320x240 resolution. This data is then sent out
to the LCD controller through SPI. The microcontroller also interfaces with the touch screen
controller through a serial interface. The user input is sent from the touch screen controller to the
microcontroller. It uses this user input to send data out from Infrared Transmitter/LED to either
the TV or the tuner box. The microcontroller can also take an input from the Infrared receiver
which receives and Infrared signal from another remote to synchronize the handheld device with
a particular TV. The microcontroller will also receive an analog input from the battery pack
through the ATD to implement the battery monitor. However, the voltage from the battery pack
will be scaled down by a factor of 2 before sending it to the ATD channel since the total voltage
from the battery pack is 7.2 V while the microcontroller pins can only support an input voltage of
maximum 5 V. The voltage scale down can be implemented with the help of a full bridge
rectifier.
2.6 Infrared Receiver/Transmitter
The Infrared transmitters are two Infrared LEDs. The microcontroller will send data to the
transmitter through serial (UART) interface and will receive data from the Infrared receiver
through the serial interface. The infrared receiver that we will use is Vishay Semiconductors
TSOP12 [7]. The receiver operates at 5 V typical and the output voltage is also 5 V. It sends the
output to the microcontroller to serial data input.
3.0 Hardware Design Narrative
The interfaces of the microcontroller that will be used are mainly one SPI, two ATD
channels, two Serial (UART), two Timer modules and 40 general I/O pins.
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ECE 477
Digital Systems Senior Design Project
Fall 2007
One of the major tasks of the microcontroller is to be able to take in the composite video
input from the Airwave AWM634X (2.4GHz RF receiver) and convert this analog input into
digital. This will be done using an Analog-To-Digital converter supported by the
microcontroller. The receiver supports four channels (2414 MHz, 2432 MHz, 2450 MHz and
2468 MHz) at which it can receive the video stream. The microcontroller can control these
channels through 3 general output pins.
The microcontroller will be interfaced with the TI ADS7843 (Touch Panel Controller)
through serial (UART) interface for data input/output and a timer module for clock input to the
controller. The touch panel requires an input clock of 2 MHz which can be obtained from the
microcontroller by using a timer module. The microcontroller will also have three general
input/output pins going into the TI ADS7843.
Another major task of the microcontroller is to be able to interface with the Epson
S1D13A04 (LCD controller). This will be done with a 4 pin SPI (with a 16 bit shift register) for
the data bus and a timer module for the clock input to the controller. The LCD controller requires
an input clock of 50 MHz (max) but the controller will be clocked at 6.4 MHz which can be
obtained from the microcontroller by using a timer module. There will also be 26 general I/O
pins from the microcontroller to the Epson S1D13A04 including the 18 bit system address bus,
the write enable and the chip select. The clock input to the LCD which is 6.4MHz.
The Power management system sends an analog signal to an ATD channel of the
microcontroller which uses this digital signal to display the battery monitor on the LCD.
The Infrared Emitters and Receivers are just IR LEDs and interface with the microcontroller
through the serial (UART) interface.
4.0 Summary
This document talks about the logic behind our hardware design and gives a preliminary
schematic of how the different components in our design interface. Under the theory of
operation, each of the major components in the design has been talked about. For each
component, the voltage requirements and the interface with the other components in the design
have been mentioned.
Under the hardware narrative, information about the project with respect to a bigger picture
can be found. This section talks about the different interfaces of the microcontroller that will be
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ECE 477
Digital Systems Senior Design Project
Fall 2007
used by the major components. With the implementation of these hardware ideas and designs,
an attempt is being made at creating a realistic prototype of a concept of the wifiMote.
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ECE 477
Digital Systems Senior Design Project
Fall 2007
List of References
[1]
Microchip Technology, “PIC24HJ256GP210”, microchip.com, [Online]. Available:
http://ww1.microchip.com/downloads/en/DeviceDoc/70175F.pdf. [Accessed Sept. 14,
2007].
[2] Microtips Technology, “MTF-T035DHSLP-A”, microtipsusa.com, [Online]. Available:
http://www.microtipsusa.com/product_pdfs/Color%20TFT/MTF-T035DHSLPA%20(24BIT,%20parallel,%20external%20BL%20control,%20anti-glare,%20TP).pdf.
[Accessed Sept. 14, 2007].
[3]
Epson Electronics America, “S1D13A04”, datasheet.in, [Online]. Available:
http://www.datasheet.in/download.php?id=534538. [Accessed Sept. 14, 2007].
[4]
Texas Instruments, “ADS7843”, focus.ti.com, [Online]. Available:
http://focus.ti.com/docs/prod/folders/print/ads7843.html. [Accessed Sept. 14, 2007].
[5] Airwave, “AWM634RX”, saelig.com, [Online]. Available: http://www.activerobots.com/products/radio-solutions/radio-modules/datasheets/awm634.pdf
[Accessed Sept. 28, 2007].
[6]
Dallas Semiconductor, “DS2715”, maxim-ic.com, [Online]. Available:
http://datasheets.maxim-ic.com/en/ds/DS2715.pdf. [Accessed Sept. 28, 2007].
[7]
Vishay Semiconductor, “TSOP12xx”, Vishay.com, [Online]. Available:
http://www.vishay.com/docs/82013/tsop12xx.pdf. [Accessed Sept. 28, 2007].
IMPORTANT: Use standard IEEE format for references, and CITE ALL REFERENCES
listed in the body of your report. Provide “live” links to all data sheets utilized.
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ECE 477
Digital Systems Senior Design Project
Appendix A: System Block Diagram
Figure 1: Block Diagram
Appendix B: Preliminary Schematic
Figure 2 : Schematic
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Fall 2007