int.doc

一个C style Assembler的source code

               T h e   8 0 5 1 F A   I n t e r r u p t   D e m o

(0) INTRODUCTION
   This is a diagnostic testing and demo program I've used when preparing
8051FA applications.  It comes in real handy when you need to verify that the
circuits containing the 8051FA will generate the correct interrupts on the
microprocessor.

   This software uses the IO library, which is an interface to a keypad and
LCD unit.  Either you will need compatible hardware, as described in the
IO reference, or you will need to write an emulation of the necessary IO
routines, for example, to  display results and read commands over a RS-232.

   For reference, these are the routines that you would need to emulate:

         * scr_init
           Initializes the display unit, clears it, and sets the cursor to
           row 0, column 0.
         * cputc
           Prints out the character contained in the accumulator A.  Moves the
           cursor right one column.  If the cursor was already at the last
           column it's location is undefined.
         * locate
           Sets the cursor to the location given by the variables Row and Col.
           Row should be in the range 0..3, and Col in the range 0..19.

You will also need to allocate 1 byte of space in internal data memory each for
the variable Row, and Col if you write your own IO routines.

(1) DISPLAY
   The display unit used with this software is a 4 x 20 LCD unit.  The top row
(row 0) is used to display the number of interrupts received from various
sources.  These numbers are single digits listed in the following format:

            Column                Interrupt Source
               0                   IE0  falling edge
               1                   IE1  falling edge
               2                   T2EX falling edge
               3                   CEX3 falling edge
               4                   CEX3 rising edge
               5                   CEX4 falling edge
               6                   CEX4 rising edge
               7                   CEX5 falling edge
               8                   CEX5 rising edge
               9                   CEX6 falling edge
              10                   CEX6 rising edge
              11                   CEX7 falling edge
              12                   CEX7 rising edge

The CEX interrupt sources can distinguish both falling edges and rising edges.

   When the count for any interrupt source exceeds 10, its count is reset to 0
and a 0 is displayed for it.

   Rows 1, 2, and 3 illustrate the concurrent execution of the interrupt loops
in TTY fashion: from column 0, rightward to column 19, and from row 1 down to
row 3.  When the display reaches the last row and column, it wraps around back
to row 1 and column 0.

   The program starts when all the interrupt loops are "Spawned" from main.
In the followiing sequence:

main:
   <a> spawn TestIE0
   <b> spawn TestIE1 
   <c> spawn TestT2EX
   <d> spawn TestCCF
   <e> start the interrupts
ret

The letters a, b, c, d, and e will be displayed as the corresponding points in
the program are reached.

Each time a CCF interrupt is triggered, a number: 0, 1, 2, 3, or 4 is displayed
corresponding to the interrupt source (0 = CCF0, 1 = CCF1, 2 = CCF2, 3 = CCF3,
and 4 = CCF4).

Finally, each of the loops is marked as follows:

TestIE0:
   Initialize IE0
   while (1) {
      <f>
      wait for IE0 interrupt
      <g>
   }

TestIE1:
   Initialize IE1
   while (1) {
      <h>
      wait for IE1 interrupt
      <i>
   }

TestT2EX:
   Initialize T2EX
   while (1) {
      <j>
      wait for T2EX interrupt
      <k>
   }

TestCCF:
   Initialize CCF0, CCF1, CCF2, CCF3, CCF4
   while (1) {
      <l>
      wait for T2EX interrupt
      <m>
   }

The letters f, g, h, i, j, k, l, and m will be displayed as the corresponding
point in each loop is reached.

   The display will therefore will be the sequence:

                     a f b h c j d i e

followed by one or more of the sequences:

         g f, i h, k j, 0 m l, 1 m l, 2 m l, 3 m l, or 4 m l.