Difference: SevenSegmentDisplayAndKeypad (4 vs. 5)

Revision 52021-01-22 - UliRaich

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META TOPICPARENT	name="Exercises"

Seven Segment Display and Keypad

The Seven Segment Display and its TM1637 controller

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Scan the keyboard in intervals of 100 ms and print the key that is pressed. This will result in printing the key as long as it is pressed.

Exercise 2:

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Wait until the key is released and only the print the key. This will result of a single key value for each button press.

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Wait until the key is released and only then print the key. This will result in a single key value for each button press.

Exercise3:

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Read the keypad in an interrupt driven routine. Keep the pressed keys in a circular buffer. Add the following methods:

available: returns true if at least 1 character is in the buffer
read: read a character and remove it from the circular buffer
status: return an overrun error if the circular buffer is full and a pressed key has been missed
flush: clear the circular buffer

Comments

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Write a CircularBuffer class in which you can keep key presses. This will allow to read the keypad completely asynchronously (see exercise 4).

The CircularBuffer class should implement a buffer of 32 elements with the following methods:

write: add an element to the end of the buffer. Check if the buffer is full before writing and set the overrun flag if this is the case
available: check if new data have arrived in the buffer
read: read data from the buffer if it is not empty
is_full: tells if the buffer is full
overrun: tells if an overrun error has occurred in the past
clr_overrun: clear the overrun flag
flush: clears the buffer

Write a test script exercising the CircularBuffer class.

Exercise 4:

Read the keypad in an interrupt driven routine. Keep the pressed keys in the circular buffer written in exercise 3.

Write a test program that starts the interrupt driven keypad driver and reads data from the circular buffer in rather large intervals (e.g. every 5s or 10s)

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