MIPS interrupt continued

1
MIPS interrupt continued
2

• Lets use this lecture to start to develop a
  simple TV controller together.
• What is left should be finished in homework 4.

3
TV controller

• It accepts simple commands like vol/-, channel
  /-, channel digit input (0-99), sleep timer, and
  power on/off.
• When there is no input, roughly every 3 seconds,
  print out the current state of the TV, in the
  format of
• Current second, Power On (of Off), Channel
  (current channel watching), volume (current
  volume), Sleep timer remaining.
• For example, At 100 second, Power On, Channel
  10, Volume 30, sleep timer 120 sec remaining.
• If power is off, only output At 100 sec, Power
  off.

4

• I didnt find a timer facility in SPIM, so the
  time is approximated using delay loops.

5
Specifications

• Initialization. When the code is run, the initial
  state is
• Power on
• Channel 0 (0-99)
• Volume 50 (0-99)
• Sleep timer off

6
Specifications

• Power key (should be p on the key board)
• When power key is pressed, if the power is
  currently off, turn on the TV immediately by
  printing Power On!
• When power key is pressed, if the power is
  currently on, turn on the TV immediately by
  printing Power Off!

7
Specification

• Channel /-. Should use u as and d as -.
  Once pressed, change the current watching channel
  accordingly (but not out of range of 0-99), and
  print out, for example, Channel 30.

8
Specifications

• Vol /-. Should use l as and k as -. Once
  pressed, change the current volume accordingly
  (but not out of range of 0-99), and print out,
  for example, Volume 30.

9
Specification

• Digit input. Use 0-9 key on key board. Used to
  change channels.
• Once a digit key is pressed, print out the
  intended channel immediately. For example, 1 is
  pressed, print out 1- immediately. The
  controller should be expecting another digit
  input for another 2 seconds. If any other key is
  pressed during these two seconds, abort the digit
  input. For example, if 1 is pressed at 1000
  second and channel is pressed at 1001 second,
  the controller should perform the channel
  function and forget about the digit input. If
  no other key is pressed during the two seconds,
  the controller switches to channel 1. If another
  digit key is pressed within the two seconds, for
  example, 2 is pressed, the controller switches
  to channel 12 immediately.

10
Specifications

• Sleep timer. Should use s key on the keyboard.
• When sleep timer key is pressed, if the sleep
  timer is off, set the sleep timer to be 10 sec.
  If the sleep timer is on, increment the sleep
  timer by 10 sec. If after that the sleep timer
  exceeds 200 sec, set the sleep timer to be off.
  Show the status of the sleep timer after
  processing the input immediately.
• If the sleep timer is on, it decrements by 1
  every second. Once it becomes 0, turn the TV off
  immediately and print out Power Off Due To Sleep
  Timer!

11
Structure of the main loop

• Check for new key board input and process the
  input.
• If power is on, check if sleep timer hits 0.
• Loop for 0.01 second.
• Print out the status if 3 seconds elapsed since
  last status print.
• Jump to the beginning of the loop.