;
;**********************************************************************
; capcmd.asm - CAPTURE subroutines for cmd monitor
;**********************************************************************
;
; created 04/03/98 -rlf
; modified 04/13/98 -rlf
;
;*********************************************************************
; Capture module interface functions
;
; The routines included in this file will read the period of a signal
; applied to CAP0 or CAP1. Timer3 is the timer resource required by the
; capture peripherals. Timer3 can be free running or Timer3 can be setup
; to start upon the detection of the first rising edge. For this
; implementation Timer3 starts upon the first rising edge on CAP0 or
; CAP1.
;
cblock
overflow
endc
;
;*********************************************************************
ReadCAP ; This routine uses ReadCAP to measure period on channel n
;*********************************************************************
;
; install this command in the CmdMenu lookup table
CmdPC = $ ; save current inline assembly PC value
org CurCmdMenuAdr ; set assembly PC to addr for new entry
; CmdMenu table entry
data "CAPn\r", CmdPC, "Measure capture channel period\r\n"
CurCmdMenuAdr = $ ; set current CmdMenu addr for next entry
org CmdPC ; begin cmd code gen at inline address
;
; The channel selection is passed in the WREG (it is necessary to
; bring it in from the cmd monitor). It is necessary to pass in the
; channel, then convert the results and wrap the appropriate
; text around the answer to be returned to the user.
; Both the selected Channel and value is returned.
;
call InitCAPn ; init capture module(s)
movlw cmdPrmBuff ; load parameter buffer address
movwf FSR1 ; into FSR1
movfp INDF1, WREG ; else put cmd value in WREG
call ReadCAPn ; read specified capture channel
btfsc ALUSTA,Z ; check return value
goto errout ; display error message
; generate output string
CpyTbl2Out CapnD ; init beginning of output buffer
movlw cmdPrmBuff ; load original parameter buffer address
movwf FSR1 ; into FSR1
movfp INDF1, WREG ; put cmd value in WREG
andlw 0x0F ; mask out upper nibble
call Dec2Buf ; convert channel into output buffer
CpyTbl2Out Eqtx ; add = 0x text
movlr 0 ; select GPR bank
movfp overflow,WREG ; retrieve multiple overflow count
call Hex2Buf ; convert overflow byte
movfp PRODH, WREG ; get MSB of capture
call Hex2Buf ; convert msb of value with no leading 0
movfp PRODL,WREG ; get LSB of capture
call Hex2Buf ; convert lsb of value with no leading 0
CpyTbl2Out CapEm ;
return ; return from Cmd
errout CpyTbl2Out Err ; add trailing text
return
; This is the end of the functions executable code
;
; These data statements store constant ascii output strings in program
; memory. They're accessed using the CpyTbl2Out macro.
;
CapnD ; constant string for capture channel
data "\nCAP", 0
Eqtx ; constant string for =
data " Period = 0x", 0
CapEm ; constant string for capture hex display
data " hex\n\r", 0
Err ; constant for error message
data "Invalid Capture Channel Entered\n\r", 0
;
;
;*********************************************************************
ReadCAPn; Read period for capture channel specified in W
;*********************************************************************
;
; This subroutine selects the capture channel, starts a
; measurement cycle then returns - leaving the result in
; CAPxH and CAPxL registers. It is called while WREG contains
; channel (1 - 4).
;
movlr 0 ; select GPR bank
clrf overflow,1 ; reset overflow register
movlb 1 ; select SFR bank
bcf PIR1,TMR3IF ; reset Timer3 overflow flag
movlb 2 ; select SFR bank
clrf TMR3H ; reset Timer3 MSB
clrf TMR3L ; reset Timer3 LSB
andlw 0x0F ; ensure upper bits are masked out
dcfsnz WREG,0 ; else, is channel 1 ?
goto rdcap1 ; yes, measure capture1 period
dcfsnz WREG,0 ; else channel 2 ?
goto rdcap2 ; yes, measure capture2 period
; dcfsnz WREG,0 ; else channel 3 ?
; goto rdcap3 ; yes, measure capture3 period
; dcfsnz WREG,0 ; else channel 4 ?
; goto rdcap4 ; measure capture4 period
bsf ALUSTA,Z ; no channel match, set error flag
return ; return with error
; ***************************************************************
; ************** READ CAPTURE CHANNEL 1
rdcap1 movlb 2 ; select SFR bank
movfp CA1H,WREG ; dummy read to transfer Master OV state
movfp CA1L,FSR1 ; dummy read to transfer Master OV state
movlb 3 ; select SFR bank
btfss TCON2,CA1OVF ; test for overflow
goto startcap1 ; no overflow so start capture
movlb 2 ; select SFR bank
movfp CA1H,WREG ; dummy read (MSB)
movfp CA1L,FSR1 ; dummy read (LSB)
movlb 1 ; select SFR bank
bcf PIR1,CA1IF ; reset capture event flag from overflow
startcap1
movlb 1 ; select SFR bank
btfss PIR1,CA1IF ; test for capture event
goto $-1 ; loop til capture event occurs
movlb 3 ; select SFR bank
bsf TCON2,TMR3ON ; start timer3
movlb 1 ; select SFR bank
bcf PIR1,CA1IF ; reset capture event flag
movlb 2 ; select SFR bank
movfp CA1H,FSR1 ; save off count (MSB)
movfp CA1L,WREG ; save off count (LSB)
movlb 1 ; select SFR bank
btfss PIR1,TMR3IF ; test for overflow
goto no_ov1 ; no overflow
bcf PIR1,TMR3IF ; reset timer3 overflow flag
movlr 0 ; select GPR bank
incf overflow,1 ; increment overflow
no_ov1 btfss PIR1,CA1IF ; test for capture event
goto $-6 ; loop til capture event occurs
bcf PIR1,CA1IF ; reset capture event flag
movlb 3 ; select SFR bank
bcf TCON2,TMR3ON ; stop timer3
movlb 2 ; select SFR bank
movfp CA1H,PRODH ; read capture MSB
movfp CA1L,PRODL ; read capture LSB
subwf PRODL,1 ; compose LSB
movpf FSR1,WREG ; retrieve MSB first read
subwfb PRODH,1 ; compose MSB
btfss ALUSTA,C ; test for borrow (MSB)
decf overflow,1 ; borrow occurred so decrement overflow
bcf ALUSTA,Z ; clear channel error flag
return ; return with results in PRODH:L
;***************************************************************
; ************** READ CAPTURE CHANNEL 2
rdcap2 movlb 3 ; select SFR bank
movfp CA2H,WREG ; dummy read to transfer Master OV state
movfp CA2L,FSR1 ; dummy read to transfer Master OV state
btfss TCON2,CA2OVF ; test for overflow
goto startcap2 ; no overflow so start capture
movfp CA2H,WREG ; dummy read (MSB)
movfp CA2L,FSR1 ; dummy read (LSB)
movlb 1 ; select SFR bank
bcf PIR1,CA2IF ; reset capture event flag
startcap2
movlb 1 ; select SFR bank
btfss PIR1,CA2IF ; test for capture event
goto $-1 ; loop til capture event occurs
movlb 3 ; select SFR bank
bsf TCON2,TMR3ON ; start timer3
movlb 1 ; select SFR bank
bcf PIR1,CA2IF ; reset capture event flag
movlb 3
movfp CA2H,FSR1 ; save off count (MSB)
movfp CA2L,WREG ; save off count (LSB)
movlb 1 ; select SFR bank
btfss PIR1,TMR3IF ; test for overflow
goto no_ov2 ; there was no Timer3 overflow
bcf PIR1,TMR3IF ; reset Timer3 overflow flag
movlr 0 ; select GPR bank
incf overflow,1 ; increment overflow count
no_ov2 btfss PIR1,CA2IF ; test for capture event
goto $-6 ; loop til capture event occurs
movlb 3 ; select SFR bank
bcf TCON2,TMR3ON ; stop timer3
movlb 1 ; select SFR bank
bcf PIR1,CA2IF ; reset capture event flag
movlb 3
movfp CA2H,PRODH ; read capture MSB
movfp CA2L,PRODL ; read capture LSB
subwf PRODL,1 ; compose LSB
movpf FSR1,WREG ; retrieve MSB first read
subwfb PRODH,1 ; compose MSB
btfss ALUSTA,C ; test for borrow (MSB)
decf overflow,1 ; borrow occurred so decrement overflow
bcf ALUSTA,Z ; clear channel error flag
return ; return with results in PRODH:L
;***************************************************************
; ************** READ CAPTURE CHANNEL 3
rdcap3
; no code available at this time
return ; return with results in ??
;***************************************************************
; ************** READ CAPTURE CHANNEL 4
rdcap4
; no code available at this time
return ; return with results in ??
;
;
;*********************************************************************
InitCAPn; Initialize the capture peripherals
;*********************************************************************
;
; Instructions: Set up CAPTURE module. Timer3 is the timer resource
; used with time-based captures.
;
movlb 7 ; select bank for control register
bsf TCON3,CA3ED0 ; set capture3 on rising edge
bsf TCON3,CA4ED0 ; set capture4 on rising edge
movlb 3 ; select bank for control register
bsf TCON1,CA1ED0 ; set capture1 on rising edge
bsf TCON1,CA2ED0 ; set capture2 on rising edge
bcf TCON1,TMR3CS ; ensure timer3 increments of internal clock
bsf TCON2,PR3 ; enable capture1 vs. period
; bsf TCON2,TMR3ON ; start timer3
return ; return from capture initialized
; end of file capcmd.asm ******************************************************
| file: /Techref/piclist/andrewspicos/capcmd.htm, 11KB, , updated: 2000/2/17 09:52, local time: 2024/11/26 03:35,
18.227.0.255:LOG IN
|
| ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://techref.massmind.org/Techref/piclist/andrewspicos/capcmd.htm"> piclist andrewspicos capcmd</A> |
| Did you find what you needed? |
Welcome to massmind.org! |
Welcome to techref.massmind.org! |
.