Post by thread:serial code

Hi there, currently there was a discussion about serial programming and not reinventing the wheel. Well, that's exactly how I feel, but I didn't catch up any piece of code. So does somebody of you have a teenie weenie piece of assembler code for reading serial data on a 2-wire interface (SCLK,DATA) ? Henri -- =============> The sanest place is still behind the trigger <=============== []-------------------------------[]---------------------------------------[] || Henri Schultze || Magdeburg D-39122 Alt-Fermersleben 88 || || spam_OUThenriTakeThisOuTfscz-md.boerde.de || The Cracker Company || []-------------------------------[]---------------------------------------[] =================> in a world of compromise, some don't <===================

Henri Schultze (.....henriKILLspam@spam@fscz-md.boerde.de) wrote: >currently there was a discussion about serial programming and not >reinventing the wheel. Well, that's exactly how I feel, but I >didn't catch up any piece of code. So does somebody of you >have a teenie weenie piece of assembler code for reading serial >data on a 2-wire interface (SCLK,DATA) ? Come on, Henri... Assembly-language programming doesn't get much easier than this. Since you didn't give any details, I'll assume that DATA is valid when SCLK is high, and that you're only reading 8 bits from the interface. #DEFINE DATA [any port] #DEFINE SCLK [any other port] RECEIVE EQU [any file register] ;.... initialize registers, setup port TRIS registers, etc. .... GETBYTE MOVLW 00000001B ;PUT A "1" IN "RECEIVE"'S LSB SO MOVWF RECEIVE ;WE'LL KNOW WHEN WE'VE RECEIVED ;8 BITS. CLRC ;ASSUME WE'LL SHIFT A "0" INTO ;"RECEIVE". GETBIT BTFSS SCLK ;WAIT FOR SCLK TO GO HIGH (CARRY GOTO $-1 ;IS ALWAYS CLEAR HERE). BTFSC DATA ;IF DATA = 0, SKIP AHEAD. SETC ;OTHERWISE, SETUP TO SHIFT A ;"1" INTO "RECEIVE". RLF RECEIVE ;SHIFT THE CARRY INTO "RECEIVE". SKPNC ;IF WE'VE RECEIVED ALL 8 BITS, GOTO DONE ;GO EXIT. BTFSC SCLK ;OTHERWISE, WAIT FOR SCLK TO GO GOTO $-1 ;LOW. GOTO GETBIT ;LOOP BACK. DONE .... ;8 BITS OF RECEIVED DATA ARE IN ;"RECEIVE". FIRST BIT RECEIVED ;IS IN THE MSB, LAST BIT IS IN ;THE LSB. -Andy -- Andrew Warren - fastfwdKILLspamix.netcom.com Fast Forward Engineering, Vista, California

-Andy wrote: > > Come on, Henri... Assembly-language programming doesn't get much easier > than this. Ohh. Shame on me :-) But I mostly end up with some optimized code from some "AN..." of the Embedded Control Handbook". So I like to see something good. And two persons (mostly) have two different ideas. So I could already catch some good idea from your code. Thanks for that. > > Since you didn't give any details, I'll assume that DATA is valid when > SCLK is high, and that you're only reading 8 bits from the interface. > Well, I didn't want bother you all to much. So I reduced the problem to a small kernel. Actually I have to interface an ADC AD7714 to a PIC hostcontroller. Things get a little bit easier when I (e.g. the PIC) provide the SCLK. BTW: it's also a 3-wire interface, but that doesn't make a difference in general. I have to send lots of control data to the ADC, then initiate a read-cycle, then read 16/24bit of data. Then I'll do just something with that conversion data I hopefully get. But plenties of time probably will walk throu the land before I get this far. Bye Henri -- {Quote hidden}> #DEFINE DATA [any port] > #DEFINE SCLK [any other port] > > RECEIVE EQU [any file register] > > ;.... initialize registers, setup port TRIS registers, etc. .... > > GETBYTE MOVLW 00000001B ;PUT A "1" IN "RECEIVE"'S LSB SO > MOVWF RECEIVE ;WE'LL KNOW WHEN WE'VE RECEIVED > ;8 BITS. > > CLRC ;ASSUME WE'LL SHIFT A "0" INTO > ;"RECEIVE". > > GETBIT BTFSS SCLK ;WAIT FOR SCLK TO GO HIGH (CARRY > GOTO $-1 ;IS ALWAYS CLEAR HERE). > > BTFSC DATA ;IF DATA = 0, SKIP AHEAD. > SETC ;OTHERWISE, SETUP TO SHIFT A > ;"1" INTO "RECEIVE". > > RLF RECEIVE ;SHIFT THE CARRY INTO "RECEIVE". > > SKPNC ;IF WE'VE RECEIVED ALL 8 BITS, > GOTO DONE ;GO EXIT. > > BTFSC SCLK ;OTHERWISE, WAIT FOR SCLK TO GO > GOTO $-1 ;LOW. > > GOTO GETBIT ;LOOP BACK. > > DONE .... ;8 BITS OF RECEIVED DATA ARE IN > ;"RECEIVE". FIRST BIT RECEIVED > ;IS IN THE MSB, LAST BIT IS IN > ;THE LSB. > > -Andy -- =============> The sanest place is still behind the trigger <=============== []-------------------------------[]---------------------------------------[] || Henri Schultze || Magdeburg D-39122 Alt-Fermersleben 88 || || .....henriKILLspam.....fscz-md.boerde.de || The Cracker Company || []-------------------------------[]---------------------------------------[] =================> in a world of compromise, some don't <===================