ECE 271                             LAB 12                             Spring 2012

EXERCISE: For this lab you will write a short program which reads and writes 
through the serial communications interface (SCI) on the HC11 and which serves as
a crude piano keyboard.

Your program will first send some prompt string such as "Piano program - use QWERTY 
row on keyboard". The user will then type keys on the keyboard and your program 
will "echo" the key back and then play a note corresponding to the key pressed.

The data area for your program will include a "keyboard map" describing the allowed 
keys, the associated frequency, and a "period". (Table on back). It will also 
include the prompt string - use fcb and enclose the string in single quotes.

Your main program will first print your prompt string (call printString). It will 
then wait for a character to be received (call getChar), echo the character to the 
screen (call putChar), and then play the tone (call PLAYTONE). It will then loop 
back and wait for a new key.

In addition to last week's getChar, putChar, and printString routines you will 
add a PLAYTONE routine: 

Subroutine PLAYTONE will play for 1/4 second the tone corresponding to the key 
passed in the A register. It must first search the table to see if there is a 
matching key and abort the routine if none is found. It will then use the two 
numbers given to play the tone as follows. First compute the frequency divided by 
two. This is the number of times to toggle the speaker in 1/4 second. The number 
following the frequency (the "period") will be used in a software delay between 
each toggle of the speaker. So, put that number in X, count down to zero, then 
toggle the speaker. In an outer loop count the number of speaker toggles and stop 
when the frequency divided by two is reached. See back for speaker information.

Doing just the above will get you 90% grade. Do more for more credit.

"NOTES":
1. As on previous labs: write good code, have flowcharts, each subroutine must be 
   transparent, etc. Flowcharts and code will be checked at the start of your lab 
   period.

2. Note that debugging will be a little more difficult than usual for the reason
   that Tute and BUFFALO are communicating over the same serial lines that you 
   will be sending data over. In particular, stepping over the lines of code where
   SCSR bits (TDRE and RDRF) are looked at and where SCDR is read/written WILL 
   NOT WORK! Also, you must switch to the "Comm" window when running.

3. Use bit instructions for all "bit" changing and testing (e.g., BRCLR, BRSET).  
   Note that bit instructions (e.g., BRCLR) must use indexed addressing - no 
   extended (EXT) addressing.

4. Partial header information is given on the back. Note that we use different 
   SCI registers than given in the text).


* Lab 12 partial header

PORTA    equ  $1000	
SPEAKER  equ  PORTA
SPEAKERBIT equ  %00100000

SCSR     equ  $6400    ; Serial communications status register
SCDR     equ  $6401    ; Serial communcations data register
TDRE     equ  %00000010		; mask for TDRE flag in SCSR
RDRF     equ  %00000001		; mask for RDRF flag in SCSR

* The following table gives key, frequency, and "period"

keymap   fdb  'q', 220, 758      ; A
         fdb  '2', 233, 715      ; A#
         fdb  'w', 247, 675      ; B
         fdb  'e', 262, 636      ; C
         fdb  '4', 277, 602      ; C#
         fdb  'r', 294, 567      ; D
         fdb  '5', 311, 536      ; D#
         fdb  't', 330, 505      ; E
         fdb  'y', 349, 478      ; F
         fdb  '7', 370, 450      ; F#
         fdb  'u', 392, 425      ; G
         fdb  '8', 415, 402      ; G#
         fdb  'i', 440, 379      ; A
         fdb  '9', 466, 358      ; A#
         fdb  'o', 494, 337      ; B
         fdb  'p', 523, 319      ; C
         fdb  '-', 554, 301      ; C#
         fdb  '[', 587, 284      ; D
         fdb  '=', 622, 268      ; D#
         fdb  ']', 659, 253      ; E
         fdb  0