;[]------------------------------------------------------------[] ;| | ;| | ;| Example program for HSETI | ;| | ;| | ;| Steven Murray, AirBorn Electronics, 1996 | ;[]------------------------------------------------------------[] ;This code is copyright (C)1996 ____________________ ;If you modify this code, put your name in the copyright entry above. ;( This example code, written by AirBorn Electronics in 1995, is released ) ;( into the public domain with no copyright claim or cover, to be copied ) ;( and modified freely, in whole or in part, to form the basis of programs ) ;( written by other parties who may in turn claim copyright on any ) ;( code added or modifications made to this material, as they desire. ) .include "8051.H" ;Without this file, the TASM assembler does not recognise any of the 8051 ; port locations automatically as other 8051 specific assemblers do. ;The file 8051.H contains all the 8051 port definitions, as equates. ;While this code is written so as to assemble on the TASM301 series ; assemblers, it should assemble with minor modification on most other ; 8051 assemblers. Indeed, you might find that other specific 8051 ; assemblers are slightly better for long term multi-project development ; work, as by its very flexible multi-CPU nature TASM is not quite as ; good at picking up syntactical coding errors as some other assemblers. .TITLE "*Demo code, AirBorn Electronics 61-2-9640-0774, V1.00a" ;This 8051 example code is for the HSETI demonstration PCB. ;Revision History -------------------------------------------------------- ;It is common practice to put a version number on each file, and a history ; at the top of the file that lists past version numbers, features added ; and bugs fixed at each step, the date, and the programmer. ;19/10/96 SM V1.00a Original skeleton code to run HSETI board ;[]------------------------[] ;| Constants | ;[]------------------------[] ;By defining constants in your program, and then using the constant's name in ; place of a numeric value, you can make your program more readable and more ; easily modifiable. Care is required, as TASM is case sensitive. ;A classic example might be "LineLen equ 80" used in a program in such a way ; that a microcontroller that happened to do output printing used "LineLen" ; in its program to format text, (e.g. "subb A,#LineLen") rather than just ; "80". At a later date it might be possible to alter the program for a ; different printer by changing LineLen to 72 or 64 - without changing code. Crystal equ 11059200 ;Crystal frequency ;The crystal is entered as an equate so that ; timing loops may be calculated at assembly ; time. By making the value for all timing ; loops dependent on this equate, just one ; number needs to be changed to alter the ; crystal frequency for all timing in the ; program. ;[]------------------------[] ;| Input/Output allocation | ;[]------------------------[] ;By defining input/outputs as equates, and then using the I/O's long name in ; place of the I/O pins name, it is easy to alter the program later for new ; hardware, and the program is more readable. ;Refer to schematic diagram AB9609231: HSETI 1 CPU PCB, to match bit names LEDsPort equ P1 LiteIn equ P3.2 SoundOut equ P3.7 ;[]------------------------[] ;| Hardware and Operational | ;[]------------------------[] ;The HSETI PCB is a simple, small PCB with a AT89C2051 CPU and a driver/buffer ;The original application was a LED display unit which was triggered from a ;light sensor, with a simple bit output to drive a speaker as well. Only the ;skeleton code is provided here - it simply counts up on all the LED outputs, ;and then sets the whole lot to zero if the light sensor goes active. At ;the same time it pulses the speaker output. You could use this code as a ;test for a newly built HSETI PCB, as it exercises all the inputs and ;outputs, and then you could write your own code to do whatever you want. ;If you are wanting to add serial COMs to your HSETI PCB, you could look ;at downloading the EX2051 PCB example.asm file, which includes serial ;routines that might be suitable. ;[]------------------------[] ;| RAM Memory allocation | ;[]------------------------[] ;Defining memory locations as equates, then using long names in referencing, ;makes a program more readable. StackBase equ 30h ;Start of stack in internal RAM ;[]------------------------[] ;| Reset/Interrupt Vectors | ;[]------------------------[] ;At reset 8051 type microprocessors start executing at location 0. There ;should be a jump at location zero to the start of the microprocessor code. ;When an 8051 type microprocessor receives an interrupt, it pushes the ;program counter onto the stack and jumps to a location near 0 - the location ;depends on the Interrupt: IE0: 3, TF0: 0Bh, IE1: 13h, TF1: 1Bh, Ser: 23h ;There should be interrupt code and/or jumps to interrupt code at these locs. ORG 0 ;CPU Jumps here at reset ;The .ORG directive starts code at that loc'tn. ;Other assemblers use "CSEG AT 0" ajmp Init ORG 3h ;CPU Calls here on external int 0, if enabled ;The program should jump here to int0 routine ajmp Stub ;INT0 is not wanted, INT0 does not happen ; unless it is enabled, but in case it does ; accidentally get enabled jump to stub ORG 0Bh ;CPU Calls here on timer 0 overflow, if enabled ajmp Stub ;The program should jump to Timer 0 routine ORG 13h ;CPU Calls here on external int 1, if enabled ;The program should jump to ext int 1 routine ajmp Stub ;INT1 int is not enabled in the example program ; and so should never happen - if it does then ; jump to "stub" ORG 1Bh ;CPU Calls here on timer 1 overflow, if enabled ;The program should jump to Timer 1 routine ajmp Stub ;TF1 int is not enabled in the example program ; and so should never happen - if it does then ; jump to "stub" ORG 23h ;CPU Calls here on Serial interrupt, if enabled ajmp Stub ;The program should jump to Serial Int routine ;[]------------------------[] ;| Interrupt Routines | ;[]------------------------[] Stub: clr EA ;Unexpected interrupt - disable all ints ;If it is possible to give some indication of ; error, such as lighting an LED, do it here acall AReti ;Flag the interrupt routine is finished ;A "reti" instruction tells the CPU that its ; interrupt routine has finished and it ; should return to the main program. ; However as we "called" the reti the CPU is ; manipulated into returning here, but in an ; "all interrupts finished" condition. ajmp Init ;Re-initialize: So unexpected Int causes reset AReti: reti ;------------------------------------------------------------------------------ ;[]------------------------[] ;| Setup | ;[]------------------------[] Init: ;Here at initialization ;Referring to the 8051 data sheets, regs (e.g. ; Acc) have a known state at reset (usually 0) ;RAM powers up indeterminate, or in the state ; it was in previously if Vcc stayed above ; the minimum power-down voltage. ;If "Init" is jumped to as part of program ; operation, then the the registers could ; have any value... we init both registers ; and RAM in this program. mov SP,#(StackBase-1) ;Initialise the Stack pointer mov PSW,#0 ;Set active register bank (Regbnk 0: Locs 0-7) clr A ;Clear all RAM - not all applications would ; want this - if you are battery backing the ; CPU and keeping values in RAM, don't clear! mov R0,#7Fh ;Start at location 7Fh - work down mov R1,#7Eh ;Do 7Eh locations - stop before R0/R1 ;DEBUG - Changed from value 7Dh 22/7/95 Put0: mov @R0,A ;Clear a byte of RAM dec R0 ;Update the RAM pointer djnz R1,Put0 ;Loop until all locations cleared dec R0 ;Clear location 0 - the last location ;[]------------------------[] ;| Main Program | ;[]------------------------[] Main: jnb LiteIn,LiteOn ;Jump if the light input is active (low) ;The light sensor input is not active acall POFDel1 ;Do a delay cpl SoundOut ;Complement the sound bit inc LEDsPort ;Increment the LED port ajmp Main ;Jump back to start LiteOn: ;The light sensor input is active acall POFDel1 ;Do a delay cpl SoundOut ;Complement the sound bit mov LEDsPort,#0h ;Turn all the LEDs off ajmp Main ;Jump back to start ;------------------------------------------------------------------------------ ;[]------------------------[] ;| Subroutines | ;[]------------------------[] POFDel equ 10 ;Desired delay in milliseconds POFDel1: mov R5,#((Crystal*POFDel)/6180000) ;Work out the djnz delay value POFDel2: ; mov R4,#0 POFDel3: djnz R4,POFDel3 ;This inside loop takes 515 cycles djnz R5,POFDel2 ;This loop happens the correct number of times ; to get closest to the desired delay in ms ret ;Return when delay is complete ;------------------------------------------------------------------------------ END