IPE01002 Foundations of Physics with Computing 2021-22
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IPE01002
Spring Semester 2021-22
Paper 4 Microcontrollers (1.5 hours)
Foundations of Physics with Computing
SECTION A
Answer ALL questions from this section |
1.
(a) Describe the key elements of a System on Chip Microcontroller using a schematic of the [4]
(i) Harvard Architecture
(ii) Identify TWO limitations of SOC systems and describe the consequences of hitting these [2]
limitations
(b) (i) A system requires 4 digital inputs, two default high, two default low – draw an electrical [4]
schematic diagram showing how you would wire these in using a 4 switches and 4 resistors (identify suitable resistor values). Leave space for adding outputs (part (ii).
(ii) The system also has 2 digital outputs which drive LEDs, draw a diagram showing how these [2]
would be wired (identify suitable resistor values)
(c) The digital inputs suffer from multiple triggering’s instead of single clean on/off signals – [2]
what components could you add to solve this problem and how would you calculate a suitable value?
(d) You decide to change one of the LEDs for a 6W 9V lamp, draw a diagram showing how you [3] would rewire the system for this change.
(e) It is decided to also add a digital display counter using a 7-seg display. This is to be driven
from 4 digital outputs, DO0, DO1, DO2, D03.
Explain how this can be achieved including a truth table. What is this mode of multiplexing [3]
called? What additional devices do you need?
2.
(a) You are designing a microcontroller system which will measure the temperature of a room
and turn on a fan when the temperature get’s too hot. A reference temperature can be set using a potentiometer. Include a master on/off switch.
(i) Draw a system block diagram for this system
[4]
(ii) Convert the system block diagram into an electrical schematic, the temperature sensor is a
PTC thermistor and the fan is being driven using a digital signal PWM.
[4]
Assuming a 5V, 8 bit uC, write the pseudocode to convert these analogue inputs to integer [4]
temperature values for the code.
(iv) The PWM motor control is designed to increase the speed of the motor when the temperature [4]
increases, but to turn off below 18ºC. Explain how the signal to the motor changes between the temperatures 0 - 55ºC
(v) It is decided that the take this system and use it in an air conditioning unit but now the fan is [4] required to be di-directional. Explain how this can be achieved using an H-bridge.
PHYSICAL CONSTANTS
2022-08-17