ECE 477
Digital Systems Senior Design Project
Spring 2009
Homework 3: Design Constraint Analysis and Component Selection Rationale
Due: Friday, February 6, at NOON
Team Code Name: Jukebox Heroes
Group No. 1
Team Member Completing This Homework: Jason Eaton
E-mail Address of Team Member: jdeaton @ purdue.edu
NOTE: This is the first in a series of four “professional component” homework assignments,
each of which is to be completed by one team member. The body of the report should be 3-5
pages, not including this cover page, references, attachments or appendices.
Evaluation:
SCORE
10
9
8
7
6
*
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
version submitted in Final Report.
Good – all requirements considered and addressed. Several noteworthy
additions/corrections needed for version submitted in Final Report.
Average – all requirements basically met, but some revisions in content should
be made for the version submitted in the Final Report.
Marginal – all requirements met at a nominal level. Significant revisions in
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.
Comments:
Comments from the grader will be inserted here.
ECE 477
Digital Systems Senior Design Project
Spring 2009
1.0 Introduction
Our project is a web enabled digital jukebox. It plays mp3 files from a usb flash drive and
provides line level audio. Users can select songs through a touchscreen or by accessing the
website from their laptops. Our product must be able to communicate with the internet over
ethernet, access files stored on a usb flash drive, decode mp3 data and convert to an audio
signal, and display information on an lcd screen.
2.0 Design Constraint Analysis
The major design constraints that I will be considering in this report are computational
requirements and interfacing with the various off-chip peripherals our design requires.
Some smaller issues briefly mentioned include power, packaging, and cost. The rationale
for the selection of our microcontroller and the various off-chip peripherals will follow the
discussion of these constraints.
2.1 Computation Requirements
Our device must perform four different computational tasks. It must service requests from
the website. It must maintain a responsive GUI. It must be able to read files from a flash
drive, and finally it must decode the mp3 data. It may have to respond to multiple web
requests simultaneously, but since it will only be accessed by the people in the shop there
will never be an enourmous volume of requests. The GUI will be fairly simple and only
needs to maintain a modest 15 frames per second. Data needs to be read from the flash drive
and decoded quickly enough to maintain a steady stream of music. In order to reasonably
handle these requirements a number of off-chip peripherals dedicated to these tasks will be
utilized.
2.2 Interface Requirements
Nineteen GPIOs will be used to interface the microcontroller with the ethernet controller.
The chosen ethernet controller and microcontroller both operate at 3.3 V, and the DCNM
-2-
ECE 477
Digital Systems Senior Design Project
Spring 2009
between the two devices is 0.4V. Current is not an issue as only single CMOS pins are
connected between these devices.
2.3 On-Chip Peripheral Requirements
Our microcontroller will need to have two channels of 10 bit ATD for reading the
touchscreen data, one I2C interface to communicate with the mp3 decoder, and one to three
SPI interfaces to communicate with the mp3 decoder, usb controller, and lcd screen. Three
SPI would allow communication with the devices to occur in parallel, but one can supply
data to all three devices if chip select GPIOs are used.
2.4 Off-Chip Peripheral Requirements
Our device will be using a number of off-chip peripherals. These include an ethernet
controller, a usb host controller, an mp3 decoder, an audo DAC, an lcd screen, and a
touchscreen overlay. Ethernet and usb are both off-chip due to the unavailablity of nonpreliminary devices that meet our requirements.
2.5 Power Constraints
Our device will be run off of A.C. power from a wall socket, will not contain any large
loads, and will have a fairly large package. All of these factors mean that power constraints
for our design are minimal.
2.6 Packaging Constraints
-3-
ECE 477
Digital Systems Senior Design Project
Spring 2009
Our device will sit against a wall, and so can have a large package size. It should be able to
withstand potential abuse from costumers and also drink spills. The touchscreen should be
easily accessable to the users.
2.7 Cost Constraints
Digital jukeboxes typically range in process from a couple hundred dollars to a few
thousand. The most expensive part of our system will be the touchscreen. We aim to make
the device as cheap as possible, but we don't really have to worry about exceeding
competitive prices.
3.0 Component Selection Rationale
Because of the extensive amount of computing that needs to be done for this project, namely
implementing a TCP/IP stack and FAT32, extensive documentation and free software
libraries are very important. For that reason we chose to go with Microchip, who have the
best documentation we saw and numerous free libraries. There were no non-preliminary
chips that had either ethernet or usb host capabilities, so both of those features were moved
off-chip. There were also no non-preliminary devices that contained three independent SPI
modules. We two families which contained as many of the peripherals as we could get were
the PIC24FJ family and the dsPIC33FJ. The dsPIC33FJ line is geared towards motor
control, which isn't relevant to our project. We chose the PIC24FJ256GP206, which
contains two SPI, two I2C, 18 channels of 12 bit A/D, a total of 53 IO pins, 64 KB of flash,
and 16 KB SRAM.
For our mp3 decoder we looked at the STA013 and the VS1001. The VS1001 contains a
built-in DAC, but is about $10 more expensive than the STA013. Because we can get a
good DAC for less than $10 we chose the STA013.
-4-
ECE 477
Digital Systems Senior Design Project
Spring 2009
For our DAC, we looked at the PCM1773 and the WM8759GED. The PCM1773 contains a
line out amplifier on each output, which the WM8759GED lacks. For this reason we chose
the PCM1773.
We looked at both the MAX3421E usb host controller and the Vinculum. The Vinculum is
much more expensive but handles the FAT32 file system. Because Microchip has FAT32
libraries, we decided that the extra functionality of the Vinculum was not needed and went
with the MAX3421E.
The two ethernet controllers we looked at were the CP2200 and the RTL8019AS. The
RTL8019AS has a 51 pin interface, requires an external EEPROM, and is really designed
for use in a PC. The CP2200 has a much simpler 19 pin interface and is designed for
embedded applications. The CP2200 was our choice for ethernet controller.
When picking out an lcd screen we looked at the EADOGM128 and the EA EDIP240B7LW. The EADOGM128 is a 128x64 pixel, 55x46 mm display while the EA EDIP240B is a
240x128 pixel, 96x60 mm display. Unfortunately, the EA EDIP240B costs $194 where the
EADOGM128 only costs $18. We decided to pick the smaller cheaper screen. The same
company also produces a touchscreen overlay which fits with the screen called the
EATOUCH128 which we will also use.
4.0 Summary
In this report I have discussed the various design constraints of our project. There is a large
amount of computation required, leading to the various off-chip peripherals included in the
device. These many peripherals require a number of communicate modules to be included
in our microcontroller. The off-chip devices were chosen primarily for there ease of use and
low cost compared to alternatives.
List of References
-5-
ECE 477
Digital Systems Senior Design Project
Spring 2009
[1] Microchip, “PIC24HJXXXGPX06/X08/X10 Data Sheet,” 2007. [online]. Available:
http://ww1.microchip.com/downloads/en/DeviceDoc/70175F.pdf.
[Accessed: Feb. 6, 2009].
[2] ST, “STA013 STA013B STA013T,” Feb. 2004. [online]. Available:
http://us.st.com/stonline/books/pdf/docs/6399.pdf. [Accessed: Feb. 6, 2009].
[3] Texas Instruments, “PCM1772, PCM1773,” Mar. 2007. [online]. Available:
http://focus.ti.com/lit/ds/symlink/pcm1773.pdf. [Accessed: Feb. 6, 2009].
[4] Maxim, “USB Peripheral/Host Controller with SPI Interface,” Feb. 2006. [online].
Available:
http://www.digchip.com/datasheets/download_datasheet.php?id=1091136&partnumber=MAX3421E. [Accessed: Feb. 6, 2009].
[5] Silicon Laboratories, “Single-Chip Ethernet Controller,” Nov. 2006. [online]. Available:
https://www.silabs.com/Support%20Documents/TechnicalDocs/CP2200_short.pdf.
[Accessed: Feb. 6, 2009].
[6] Electronic Assembly, “DOGM Graphic Series,” Oct. 2008. [online]. Available:
http://www.lcd-module.de/eng/pdf/grafik/dogm128e.pdf. [Accessed: Feb. 6, 2009].
-6-
ECE 477
Digital Systems Senior Design Project
-7-
Spring 2009
ECE 477
Digital Systems Senior Design Project
Fall2008
Appendix A: Parts List Spreadsheet
Vendor
Mouser
Mouser
Mouser
Mouser
Mouser
DigiKey
Futurlec
Manufacturer
Electronic Assembly
Electronic Assembly
Texas Instruments
Microchip
Silicon Labs
Maxim
ST
Part No.
EADOGM128
EATOUCH128
PCM1773PW
PIC24FJ256GP206
CP2200
MAX3421E
STA013
Description
128x64 pixel lcd screen
Touchscreen Overlay
Audio DAC
Microcontroller
Ethernet Controller
USB Controller
MP3 Decoder
Unit Cost Qty
$18.00
1
$13.16
1
$2.81
1
$6.84
1
$7.72
1
$11.10
1
$6.90
1
TOTAL
-8-
Total Cost
$18.00
$13.16
$2.81
$6.84
$7.72
$11.10
$6.90
$66.53
ECE 477
Digital Systems Senior Design Project
Appendix B: Updated Block Diagram
-9-
Fall2008
ECE 477
Digital Systems Senior Design Project
-10-
Fall2008