Please title this page. (a2dcmd.htm)

; ;*++ mls28FEB98 analog subroutines for cmd monitor: Disti Cert 98 ; ; modified 3/21/98 -jea ; ;********************************************************************* ; A/D interface functions ;********************************************************************* ReadAD ; This routine uses ReadADn to get the A/D value from 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 "ANn\r", CmdPC, "Read A/D channel n\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 SetupAD ; init A/D movlw cmdPrmBuff ; load parameter buffer address movwf FSR1 ; into FSR1 movfp INDF1, WREG ; put channel selection into WREG call ReadADn ; read specified analog channel ; generate output string CpyTbl2Out AnD ; init beginning of output buffer movlb 5 ; be sure bank 5 stil selected swapf ADCON0, w ; move channel to w and swap ends andlw 0x00F ; mask extraneous bits call Dec2Buf ; convert channel into output buffer CpyTbl2Out EqtD ; add = text movfp ADRESH, WREG ; get 0, 1, 2, or 3 from MSbyte andlw 0x03 ; mask out upper bits call Dec2Buf ; convert msb of value with no leading 0 movfp ADRESL, WREG ; get lsb of a/d value call Hex2Buf ; convert lsb as a hex number CpyTbl2Out FsD ; add trailing text return ; return from Cmd ; 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. AnD ; constant string for analog channel data "\nAN",0 EqtD ; constant string for = data " = ",0 FsD ; constant string for trailing text data " hex, of 3FF Full Scale\n\r",0 ; ; ;********************************************************************* ReadTmp ; This routine uses ReadADn to read the thermister on A/D channel 4 ;********************************************************************* ; ; 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 "T\r", CmdPC, "Read thermnister on A/D channel 4\r\n" CurCmdMenuAdr = $ ; set current CmdMenu addr for next entry org CmdPC ; begin cmd code gen at inline address ; ; This routine uses ReadADn to get the raw ADC count. Channel ; selection is passed in the WREG (4 for the Thermistor). The ; following assumption may be used to convert from raw ADC to ; degrees F: within a small range around room temperature, the ADC ; count changes one count per degree F; the 10 bit count at 77 deg F ; is dec 930. Hint: the two MSbs are always set at room temperature ; together they are worth 256 + 512 = 768. ; call SetupAD ; init A/D movlw 4 ; select channel 4 call ReadADn ; get raw adc count (ignore 2 MSBs) CpyTbl2Out ThrmD movlb 5 ; bank select movlw 0x055 ; in addition to two msbs (being ignored) subwf ADRESL, W ; subtract 85 from lsb for temperature F call Dec2Buf ; convert into output buffer CpyTbl2Out DegD ; add trailing text return ; return from Cmd ; 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 CpyTbl2Buf and CpyTblCont macros ; with the addresses given by the labels. ThrmD ; constant string for thermister data "\nThermistor temp = ", 0 DegD ; constant string for trailing text data " deg Fahrenheit\n\r", 0 ; ;********************************************************************* ReadADn ; Read the A/D channel specified in W ;********************************************************************* ; ; This subroutine selects the channel, waits for settling time, starts ; the conversion, waits for completion, then returns - leaving the ; result in ADRESx. It is called while WREG contains channel (0 - 11) ; inclusive leaves right justified result in ADRESL and 'H and ; insures channel selected does not exceed 11. ; movlb 5 ; AD work in Bank 5 andlw 0x0F ; test and limit channel to valid range movwf ADRESH ; temporary storage btfsc ADRESH, 3 ; 12 or greater is invlalid: bcf ADRESH, 2 ; if 8 set insure 4 is not swapf ADRESH, W ; value belongs in upper nibble iorlw 0x01 ; also turn on AD without starting conv movwf ADCON0 ; load into A/D control reg ; delay settle time, ~50 uSec: ~200 instruction cycles at 16 MHz movlw 0x040 ; 64 * 3 * .25 uSec = 48uSec movwf ADRESH ; temporary storage decfsz ADRESH ; decrement until 0 goto $-1 ; until then wait bsf ADCON0, 2 ; start conversion btfsc ADCON0, 2 ; loop til conversion complete goto $-1 return ; return with results in ADRESx ; ;********************************************************************* SetupAD ; Init the A/D peripheral ;********************************************************************* ; ; Instructions: (Don't forget to select Bank) ; ADCON0 ; Select AN0, Turn on AD, do not start AD ; ADCON1 ; The processor clock is 16MHz; select the AD conversion clock so ; Tad is fast, but in spec. Right justify for ease of processing. ; Enable all analog inputs. Use Vdd & Vss as Ref rails. ; Make sure the relevant data direction bits are set! ; movlb 5 ; select bank 5 movlw b'00000001' ; Select AN0, turn on AD, do not start AD movwf ADCON0 ; in ADCON0 movlw b'01110000' ; Tad clk = Fosc/32 = 2 uSec Tad per. ; Right justify, Enable all analog inputs ; Use Vdd & Vss as Ref rails movwf ADCON1 ; in ADCON1 movlw 0x0F ; mask to set digital input iorwf DDRG ; in DDRG for AN0 - AN3 movlw 0xFF ; mask to set digital input iorwf DDRF ; on DDRF for AN4 - AN11 return ; return with A/D initialized ; end of file a2dcmd.asm ********************************************************