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|
;//###########################################################################
;//
;// FILE: F2837xD_usDelay.asm
;//
;// TITLE: Simple delay function
;//
;// DESCRIPTION:
;// This is a simple delay function that can be used to insert a specified
;// delay into code.
;// This function is only accurate if executed from internal zero-waitstate
;// SARAM. If it is executed from waitstate memory then the delay will be
;// longer then specified.
;// To use this function:
;// 1 - update the CPU clock speed in the F2837xD_Examples.h
;// file. For example:
;// #define CPU_RATE 6.667L // for a 150MHz CPU clock speed
;// 2 - Call this function by using the DELAY_US(A) macro
;// that is defined in the F2837xD_Device.h file. This macro
;// will convert the number of microseconds specified
;// into a loop count for use with this function.
;// This count will be based on the CPU frequency you specify.
;// 3 - For the most accurate delay
;// - Execute this function in 0 waitstate RAM.
;// - Disable interrupts before calling the function
;// If you do not disable interrupts, then think of
;// this as an "at least" delay function as the actual
;// delay may be longer.
;// The C assembly call from the DELAY_US(time) macro will
;// look as follows:
;// extern void Delay(long LoopCount);
;// MOV AL,#LowLoopCount
;// MOV AH,#HighLoopCount
;// LCR _Delay
;// Or as follows (if count is less then 16-bits):
;// MOV ACC,#LoopCount
;// LCR _Delay
;//
;//###########################################################################
;// $TI Release: F2837xD Support Library v3.05.00.00 $
;// $Release Date: Tue Jun 26 03:15:23 CDT 2018 $
;// $Copyright:
;// Copyright (C) 2013-2018 Texas Instruments Incorporated - http://www.ti.com/
;//
;// Redistribution and use in source and binary forms, with or without
;// modification, are permitted provided that the following conditions
;// are met:
;//
;// Redistributions of source code must retain the above copyright
;// notice, this list of conditions and the following disclaimer.
;//
;// Redistributions in binary form must reproduce the above copyright
;// notice, this list of conditions and the following disclaimer in the
;// documentation and/or other materials provided with the
;// distribution.
;//
;// Neither the name of Texas Instruments Incorporated nor the names of
;// its contributors may be used to endorse or promote products derived
;// from this software without specific prior written permission.
;//
;// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
;// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
;// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
;// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
;// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
;// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
;// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
;// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
;// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
;// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
;// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;// $
;//###########################################################################
.cdecls LIST ;;Used to populate __TI_COMPILER_VERSION__ macro
%{
#ifdef __TI_EABI__
#define __EABI__ 1
#else
#define __EABI__ 0
#endif
%}
.if __EABI__
.def F28x_usDelay
.else
.def _F28x_usDelay
.endif
.if __TI_COMPILER_VERSION__
.if __TI_COMPILER_VERSION__ >= 15009000
.sect ".TI.ramfunc" ;;Used with compiler v15.9.0 and newer
.else
.sect "ramfuncs" ;;Used with compilers older than v15.9.0
.endif
.endif
.global __F28x_usDelay
.if __EABI__
F28x_usDelay:
.else
_F28x_usDelay:
.endif
SUB ACC,#1
.if __EABI__
BF F28x_usDelay,GEQ ;; Loop if ACC >= 0
.else
BF _F28x_usDelay,GEQ ;; Loop if ACC >= 0
.endif
LRETR
;There is a 9/10 cycle overhead and each loop
;takes five cycles. The LoopCount is given by
;the following formula:
; DELAY_CPU_CYCLES = 9 + 5*LoopCount
; LoopCount = (DELAY_CPU_CYCLES - 9) / 5
; The macro DELAY_US(A) performs this calculation for you
;
;
;//
;// End of file
;//
|
