ELET2100 - MICROPROCESSORS I
COURSE TEST #2 - WEDNESDAY 19th NOVEMBER 2008
Time: (3:00 - 4:00 )PM
( 1 ) The Timer on the spare 8155 IC on the SDK-85 kit is allocated the
port #'s 2BH & 2CH. Write an AL program to perform the following algorithm:
(a) Load the Timer into the mode which will 'fire' a pulse &
repeat it every 1 ms
(b) Start the Timer
(c) Use the Timer output to trigger a RST5.5 interrupt
(d) Have the ISR for the interrupt turn ON all the LED’s 0 & 7 only,
connected to Port 00H
(e) Stop the Timer [10]
[ State the Timer input frequency you used. ]
( 2 ) You are asked to design an 8-bit A/D system to read data in from two (2) sensors,
both rated at 0 - 2.0 DC volts full scale.
Show a diagram of your A/D system, with its various signals that are
allocated to Ports/Bits on an SDK-85 kit.
Write an AL program that takes ten (10) readings from the sensors and stores the
values for Sensor 1 starting at memory location 4000H, and those from Sensor 2
starting at memory location 5000H. [12]
[ State all assumptions made. ]
( 3 ) For the following, indicate T -true or F – false, where necessary:
(a) In serial transmission, bit D7 is sent after the Stop bit [1]
(b) Using 7-data bits & odd parity, the letter B (42H) is sent as C2H (8-bits) [1]
(c) The delay between bits for 9600 baud is approx. 0.01 ms [1]
(d) To send a logic 1 on the serial SOD line, both bits D7 & D6 of the A-register
must be at logic 1 before executing SIM [1]
(e) Draw & label the waveform of the letter M (4DH) with 7-data bits,
even parity, 1-stop bit [3]
(f) At a baud rate of 56.6K, 8-data + 1-parity + 1-stop (bits), how long would
it take to transmit the sentence :
“ELECTRONICS IS FUN”
[ Do not include the “ characters but do include the <blank> spaces ] [3]
( 4 ) Using the A/D converter system in Question 2:
(a) what is the resolution of the sensors ? [1]
(b) what design change would improve this resolution ? [1]
(c) what design change would allow an increase in the number of channels ? [1]
Bonus mark: The Lab Demonstrator assigned to the course is Mr. ? Guppy.
What is his First name ?
Maximum mark = 35