A LED PATTERN DISPLAY SYSTEM
1. Design a microprocessing system to implement the following LED pattern display system.
An LED display device contains a grid of 25 LEDs, as shown in Fig. 1. An LED in the grid may be turned on by
applying +5V to the grid point. For example, (R4,C3) = (+5V,+5V) will turn on the LED at grid point (R4,C3).
Two or more LEDs may be turned on. For example, (R1,C2) = (+5V,+5V) and (R2,C2) = (+5V,+5V) will turn on
the LEDs at grid points (R1,C2) and (R2,C2). To turn on a set of LEDs, each of the desired LEDs in the set must
be turned on. A set of LEDs may be turned on by applying the 10-bit pattern to the inputs of the LED display
device, and then latching the 10-bit code by applying a positive edge (low-high) on the Latch signal (See Fig. 1).
For example, to turn on the top first row of LEDs, the following 10-bit pattern should be latched into the LED
display device: {R1R2R3R4R5C1C2C3C4C5} = 1000011111.
Your design is supposed to shine the LEDs in the following sequence: Set 1, Set 2, Set 3, Set 1, Set 2, Set 3, Set
1, ... The three sets of LEDs are shown in Fig. 1. Note: when shining a set of LEDs, all of the LEDs in the set
should be turned on simultaneously.
The system should shine the LEDs in the given sequence (pattern) only when the user presses the Start button.
Note: After the Start button has been released, the system should continue shining the LEDs until the user presses
the Stop button.
At any time the user may change the speed of shining the LEDs. The user may select LOW, MED, or FAST
speed. The LOW speed is defined as 1000ms between shining two consecutive sets of LEDs. The MED speed is
defined as 100ms between shining two consecutive sets of LEDs. The HIGH speed is defined as 10ms between
shining two consecutive sets of LEDs. For example, for the HIGH speed setting, the system should shine each set
for 10ms.
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Timer Device: as shown in Fig. 1(a), the timer device has a RO pin, which provides a pulse (high-low-high)
each time the timer reaches the timeout value. The timeout value is configurable as multiples of 10ms. The
procedure for configuring the time out value is as follows: First, the Timeout Configuration Enable pin
(TCE) pin must be set to 0V; Then, the TOV pin should be pulsed (high-low-high) a number of times equal to
the desired multiple of 10ms time out value. For example, if you want the time out value to be 10ms, then
you must pulse the TOV pin one time. If you want the time out value to be 100ms, then you must pulse the
TOV pin 10 times. Finally, the TCE pin must be returned to 5V. The timer also has a Start/Stop pin, which is
used to start and stop the timer.
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Table 1: Control Panel
Timer
RO
(b)
Start/Stop
TCE
TOV
START
1
CP2
STOP
2
CP1
RESET
3
CP0
CP2
0
0
0
0
1
1
1
1
(a)
CP1
0
0
1
1
0
0
1
1
CP0
0
1
0
1
0
1
0
1
FCN
NONE
START
STOP
RESET
LOW
MED
HIGH
NONE
(c)
Latch
R1
R2
R3
R4
R5
C1
C2
C3
C4
C5
C1
R1
R2
C2
C3
C4
C5
(d)
Set 1: (R1,C1), (R2,C1), (R3,C1), (R4,C1), (R5,C1)
Set 2: (R2,C2), (R3,C2), (R4,C2)
Set 3: (R3,C3)
R3
R4
R5
Fig. 1. (a) Given Timer device. (b) Control Panel, (c) LED device, (d) Pattern.
The following describes the parts you may use in your design:
Available Parts (no other devices are permitted)
• A basic micro-processor (You may use the HC11 or the HCS12 instruction set).
• Three 512x8 ROM chips. Each ROM chip has two active low chip selects (CS0 and CS1).
• One 128x8 ROM chip, with one active low chip select (CS).
• Eight 32Kx8 RAM chips. Each RAM chip has one active high chip select (CS).
• One 64x8 RAM chip, with one active low chip select (CS).
• Many 4-Port PCIAs. Each PCIA has one active low chip select (CS).
• An ATD converter, having 8-bit resolution and a fixed sampling frequency of 8 kHz.
• Two DTA converters, which convert 8-bit numbers to the range of 0V to 5V in 256. steps.
[1.1]
Create and draw a system block diagram of your design.
[1.2]
Design and show an address decoder for your system.
[1.3]
Draw a diagram of the memory map for this system. Include the address ranges of all memories
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and I/O controllers. Also, show the starting and ending addresses of the program code area,
data area, and stack area. Also, show the contents of the vector table.
[1.4]
Draw a flow chart for every part of your software.
[1.5]
Design and write all software for your system.
2. Analysis Questions
[2.1]
If you are using a stack, how large does your stack grow?
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