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Guys/Gals: I can't seem to get the tx i/o to flip. I could spend endless hours screwing with the hardware (since MPLab doesn't support serial functions) or I could ask the infinite intellegence (i.e., you the group) for direction. I choose the latter. Here is my code, all I want to see is that tx i/o flip on my scope. The counter just makes the bits change so I know it's alive. I'm sure it's something stupid, but not having done this before I could sure use some help. TIA, John. ;============================== list pF628 __config h'3d31' ; XT oscillator radix hex include <p16f628.inc> byte equ 1 word equ 2 cblock 0x20 count1 :byte endc ; end c block org 0x000 ; program memory at reset vector 0x000 reset goto setup ; set up ints and port stuff org 0x004 ; Interrupt vector, int handler code next ;============================== ; setup routine ;============================== setup movlw b'00000111' ; turn off analog I/O movwf CMCON movlw b'00000000' ; turn off interrupt movwf INTCON bcf STATUS, RP1 BSF STATUS, RP0 ; switch bank MOVLW 0XFF ; set port A to inputs MOVWF TRISA movlw b'00000110' ; set port B to outputs, tx/rx on movwf TRISB BCF STATUS, RP0 clrf PORTA clrf PORTB ;============================== ; Main Loop ;============================== main bsf RCSTA,7 ; set SPEN bsf TRISB,2 ; rx/tx output bsf TRISB,1 bsf TXSTA,3 ; BRGH high movlw b'00011001' ; dec25 movwf SPBRG ; set baud rate bcf TXSTA,4 ; clr SYNC bsf RCSTA,7 ; set SPEN bsf TXSTA,5 ; set TXEN incf count1, f movlw count1 movwf TXREG main2 btfss PIR1,4 goto main2 goto main ;============================== ; End ;============================== end |
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Serial I/O on the 16F628
Started by ●November 16, 2004
Reply by ●November 16, 20042004-11-16
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I haven't worked through all the code but at main RP0 = 0 and RP1 = 0
and you are writing to TRISB which is in bank 1 (I cannot remember where the other SFRs live off the top of my head), then further down in main you access count1 which is in bank 0. I think you should go over your code paying careful attention to which bank each of the registers (and SFRs) are in and ensure that RP0 and RP1 are set correctly. Regards Sergio Masci http://www.xcprod.com/titan/XCSB - optimising PIC compiler FREE for personal non-commercial use ----- Original Message ----- From: jrem <> To: <> Sent: Tuesday, November 16, 2004 2:13 PM Subject: [piclist] Serial I/O on the 16F628 > > > Guys/Gals: > > I can't seem to get the tx i/o to flip. I could spend endless hours > screwing with the hardware (since MPLab doesn't support serial > functions) or I could ask the infinite intellegence (i.e., you the > group) for direction. I choose the latter. > > Here is my code, all I want to see is that tx i/o flip on my scope. > The counter just makes the bits change so I know it's alive. > > I'm sure it's something stupid, but not having done this before I > could sure use some help. > > TIA, John. > ;============================== > list pF628 > __config h'3d31' ; XT oscillator > radix hex > include <p16f628.inc> > > byte equ 1 > word equ 2 > cblock 0x20 > count1 :byte > endc ; end c block > > org 0x000 ; program memory at reset vector 0x000 > reset > goto setup ; set up ints and port stuff > org 0x004 ; Interrupt vector, int handler code next > > ;============================== > ; setup routine > ;============================== > > setup > movlw b'00000111' ; turn off analog I/O > movwf CMCON > movlw b'00000000' ; turn off interrupt > movwf INTCON > bcf STATUS, RP1 > BSF STATUS, RP0 ; switch bank > MOVLW 0XFF ; set port A to inputs > MOVWF TRISA > movlw b'00000110' ; set port B to outputs, tx/rx on > movwf TRISB > BCF STATUS, RP0 > clrf PORTA > clrf PORTB > > ;============================== > ; Main Loop > ;============================== > > main > bsf RCSTA,7 ; set SPEN > bsf TRISB,2 ; rx/tx output > bsf TRISB,1 > bsf TXSTA,3 ; BRGH high > movlw b'00011001' ; dec25 > movwf SPBRG ; set baud rate > bcf TXSTA,4 ; clr SYNC > bsf RCSTA,7 ; set SPEN > bsf TXSTA,5 ; set TXEN > > incf count1, f > movlw count1 > movwf TXREG > > main2 btfss PIR1,4 > goto main2 > goto main > > ;============================== > ; End > ;============================== > > end |
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Reply by ●November 16, 20042004-11-16
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I was wondering about that, thanks, I knew it was something stupid. --- In , "sergio masci" <smypl@x> wrote: > I haven't worked through all the code but at main RP0 = 0 and RP1 = 0 and > you are writing to TRISB which is in bank 1 (I cannot remember where the > other SFRs live off the top of my head), then further down in main you > access count1 which is in bank 0. I think you should go over your code > paying careful attention to which bank each of the registers (and SFRs) are > in and ensure that RP0 and RP1 are set correctly. > > Regards > Sergio Masci > > http://www.xcprod.com/titan/XCSB - optimising PIC compiler > FREE for personal non-commercial use > > ----- Original Message ----- > From: jrem <jrem123@y...> > To: <> > Sent: Tuesday, November 16, 2004 2:13 PM > Subject: [piclist] Serial I/O on the 16F628 > > > > > > Guys/Gals: > > > > I can't seem to get the tx i/o to flip. I could spend endless hours > > screwing with the hardware (since MPLab doesn't support serial > > functions) or I could ask the infinite intellegence (i.e., you the > > group) for direction. I choose the latter. > > > > Here is my code, all I want to see is that tx i/o flip on my scope. > > The counter just makes the bits change so I know it's alive. > > > > I'm sure it's something stupid, but not having done this before I > > could sure use some help. > > > > TIA, John. > > > > > > ;============================== > > list pF628 > > __config h'3d31' ; XT oscillator > > radix hex > > include <p16f628.inc> > > > > byte equ 1 > > word equ 2 > > cblock 0x20 > > count1 :byte > > endc ; end c block > > > > org 0x000 ; program memory at reset vector 0x000 > > reset > > goto setup ; set up ints and port stuff > > org 0x004 ; Interrupt vector, int handler code next > > > > ;============================== > > ; setup routine > > ;============================== > > > > setup > > movlw b'00000111' ; turn off analog I/O > > movwf CMCON > > movlw b'00000000' ; turn off interrupt > > movwf INTCON > > bcf STATUS, RP1 > > BSF STATUS, RP0 ; switch bank > > MOVLW 0XFF ; set port A to inputs > > MOVWF TRISA > > movlw b'00000110' ; set port B to outputs, tx/rx on > > movwf TRISB > > BCF STATUS, RP0 > > clrf PORTA > > clrf PORTB > > > > ;============================== > > ; Main Loop > > ;============================== > > > > main > > bsf RCSTA,7 ; set SPEN > > bsf TRISB,2 ; rx/tx output > > bsf TRISB,1 > > bsf TXSTA,3 ; BRGH high > > movlw b'00011001' ; dec25 > > movwf SPBRG ; set baud rate > > bcf TXSTA,4 ; clr SYNC > > bsf RCSTA,7 ; set SPEN > > bsf TXSTA,5 ; set TXEN > > > > incf count1, f > > movlw count1 > > movwf TXREG > > > > main2 btfss PIR1,4 > > goto main2 > > goto main > > > > ;============================== > > ; End > > ;============================== > > > > end |
Reply by ●November 16, 20042004-11-16
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John, I made a few changes but didn't rewrite the code. It looks like it should work but I didn't test it. If it is still a problem, post back and I'll run it on a proto board. I can't test the XT oscillator configuration - my board is set for 20 MHz. Richard --- In , "jrem" <jrem123@y...> wrote: > > Guys/Gals: > > I can't seem to get the tx i/o to flip. I could spend endless hours > screwing with the hardware (since MPLab doesn't support serial > functions) or I could ask the infinite intellegence (i.e., you the > group) for direction. I choose the latter. > > Here is my code, all I want to see is that tx i/o flip on my scope. > The counter just makes the bits change so I know it's alive. > > I'm sure it's something stupid, but not having done this before I > could sure use some help. > > TIA, John. > ;============================== > list pF628 > __config h'3d31' ; XT oscillator > radix hex > include <p16f628.inc> > > byte equ 1 > word equ 2 > cblock 0x20 > count1 :byte > endc ; end c block > > org 0x000 ; program memory at reset vector 0x000 > reset CLRF STATUS ; good place for this if there is room > goto setup ; set up ints and port stuff > org 0x004 ; Interrupt vector, int handler code next > > ;============================== > ; setup routine > ;============================== > > setup > movlw b'00000111' ; turn off analog I/O > movwf CMCON > movlw b'00000000' ; turn off interrupt > movwf INTCON BANKSEL PORTA > clrf PORTA ; *** do the port initialization first > clrf PORTB BANKSEL TRISA > MOVLW 0XFF ; set port A to inputs > MOVWF TRISA > movlw b'00000110' ; set port B to outputs, tx/rx on > movwf TRISB > > ;============================== > ; Main Loop > ;============================== > > main > bsf RCSTA,7 ; set SPEN BANKSEL TXSTA > bsf TXSTA,2 ; BRGH high *** changed bit *** > movlw b'00011001' ; dec25 > movwf SPBRG ; set baud rate > bcf TXSTA,4 ; clr SYNC > bsf TXSTA,5 ; set TXEN BANKSEL RCSTA > bsf RCSTA,7 ; set SPEN > main1 BANKSEL TXREG > incf count1, f MOVF count1,W ; *** changed instruction *** > movwf TXREG BANKSEL TXSTA > > main2 btfss TXSTA,4 > goto main2 > goto main1 > > ;============================== > ; End > ;============================== > > end |
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Reply by ●November 16, 20042004-11-16
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John, I went ahead and rewrote the code. It works on my demo board with a 20 MHz resonator at 38400 baud: list pF628A,r,nH #include <p16f628a.inc> errorlevel -302 ;suppress "not in bank 0" message FALSE EQU 0 TRUE EQU ! FALSE ifdef __16F877 BootLoader EQU TRUE else BootLoader EQU FALSE endif if ! BootLoader __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _HS_OSC & _LVP_OFF endif byte equ 1 word equ 2 cblock 0x20 count1 :byte endc ; end c block ;This code executes when a reset occurs. ResetCode: if ! BootLoader org 0x0000 clrf STATUS clrf PCLATH else org 0x0003 endif goto setup ;go to beginning of program ;-------------------------------- -------- ;This code executes when an interrupt occurs. ORG 0x0004 ;place code at interrupt vector InterruptCode: ;============================== ; setup code ;============================== setup movlw b'00000111' movwf CMCON movlw b'00000000' movwf INTCON banksel PORTA clrf PORTA clrf PORTB banksel TRISA movlw 0xFF movwf TRISA movlw b'00000110' movwf TRISB bsf RCSTA,SPEN ; don't think this is necessary banksel TXSTA bsf TXSTA,BRGH movlw d'31' movwf SPBRG bcf TXSTA,SYNC ; don't think this is necessary bsf TXSTA,TXEN banksel RCSTA bsf RCSTA,SPEN ;============================== ; main loop ;============================== main banksel TXREG incf count1,f movf count1,w movwf TXREG banksel TXSTA main1 btfss TXSTA,TRMT goto main1 goto main end Richard |
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Reply by ●November 16, 20042004-11-16
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OOPS - there is an extraneous line --- In , "rtstofer" <rstofer@p...> wrote: > > John, > > I went ahead and rewrote the code. It works on my demo board with a > 20 MHz resonator at 38400 baud: > > list pF628A,r,nH > #include <p16f628a.inc> > > errorlevel -302 ;suppress "not in bank 0" message > > FALSE EQU 0 > TRUE EQU ! FALSE > > ifdef __16F877 > BootLoader EQU TRUE > else > BootLoader EQU FALSE > endif > > if ! BootLoader > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & > _HS_OSC & _LVP_OFF > endif > > byte equ 1 > word equ 2 > > cblock 0x20 > count1 :byte > endc ; end c block > > ;This code executes when a reset occurs. > ResetCode: > if ! BootLoader > org 0x0000 > clrf STATUS > clrf PCLATH > else > org 0x0003 > endif > > goto setup ;go to beginning of program > > ;------------------------------ -- > -------- > ;This code executes when an interrupt occurs. > > ORG 0x0004 ;place code at interrupt > vector > > InterruptCode: > > ;============================== > ; setup code > ;============================== > setup > movlw b'00000111' > movwf CMCON > movlw b'00000000' > movwf INTCON > > banksel PORTA > clrf PORTA > clrf PORTB > > banksel TRISA > movlw 0xFF > movwf TRISA > movlw b'00000110' > movwf TRISB > ****** REMOVE THE FOLLOWING LINE > bsf RCSTA,SPEN ; don't think this is necessary ****** > > banksel TXSTA > bsf TXSTA,BRGH > movlw d'31' > movwf SPBRG > bcf TXSTA,SYNC ; don't think this is necessary > bsf TXSTA,TXEN > > banksel RCSTA > bsf RCSTA,SPEN > > ;============================== > ; main loop > ;============================== > main > banksel TXREG > incf count1,f > movf count1,w > movwf TXREG > > banksel TXSTA > > main1 > btfss TXSTA,TRMT > goto main1 > goto main > > end > Richard |
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Reply by ●November 16, 20042004-11-16
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cool, thanks . . . I like that 'banksel' instead of bsf status,rp0 etc. per 16F62x datasheet (ds40300c) page 75, item #2 "enable the asynchronous serial port by clearing bit SYNC and setting bit SPEN". looks like if SPEN is cleared then the usart is disabled, what gives? thanks . . . John. --- In , "rtstofer" <rstofer@p...> wrote: > > > OOPS - there is an extraneous line > > --- In , "rtstofer" <rstofer@p...> wrote: > > > > John, > > > > I went ahead and rewrote the code. It works on my demo board with > a > > 20 MHz resonator at 38400 baud: > > > > list pF628A,r,nH > > #include <p16f628a.inc> > > > > errorlevel -302 ;suppress "not in bank 0" > message > > > > FALSE EQU 0 > > TRUE EQU ! FALSE > > > > ifdef __16F877 > > BootLoader EQU TRUE > > else > > BootLoader EQU FALSE > > endif > > > > if ! BootLoader > > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & > > _HS_OSC & _LVP_OFF > > endif > > > > byte equ 1 > > word equ 2 > > > > cblock 0x20 > > count1 :byte > > endc ; end c block > > > > ;This code executes when a reset occurs. > > ResetCode: > > if ! BootLoader > > org 0x0000 > > clrf STATUS > > clrf PCLATH > > else > > org 0x0003 > > endif > > > > goto setup ;go to beginning of program > > > > ;----------------------------- - > -- > > -------- > > ;This code executes when an interrupt occurs. > > > > ORG 0x0004 ;place code at interrupt > > vector > > > > InterruptCode: > > > > ;============================== > > ; setup code > > ;============================== > > setup > > movlw b'00000111' > > movwf CMCON > > movlw b'00000000' > > movwf INTCON > > > > banksel PORTA > > clrf PORTA > > clrf PORTB > > > > banksel TRISA > > movlw 0xFF > > movwf TRISA > > movlw b'00000110' > > movwf TRISB > > > ****** REMOVE THE FOLLOWING LINE > > bsf RCSTA,SPEN ; don't think this is necessary > ****** > > > > banksel TXSTA > > bsf TXSTA,BRGH > > movlw d'31' > > movwf SPBRG > > bcf TXSTA,SYNC ; don't think this is necessary > > bsf TXSTA,TXEN > > > > banksel RCSTA > > bsf RCSTA,SPEN > > > > ;============================== > > ; main loop > > ;============================== > > main > > banksel TXREG > > incf count1,f > > movf count1,w > > movwf TXREG > > > > banksel TXSTA > > > > main1 > > btfss TXSTA,TRMT > > goto main1 > > goto main > > > > end > > > > > > Richard |
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Reply by ●November 16, 20042004-11-16
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----- Original Message ----- From: jrem <> To: <> Sent: Tuesday, November 16, 2004 6:37 PM Subject: [piclist] Re: Serial I/O on the 16F628 > > > cool, thanks . . . I like that 'banksel' instead of bsf status,rp0 > etc. In XCASM you don't have to select the bank explicitly, the assembler inserts bank select instructions for you when needed - but I digress :-) > > per 16F62x datasheet (ds40300c) page 75, item #2 "enable the > asynchronous serial port by clearing bit SYNC and setting bit SPEN". > > looks like if SPEN is cleared then the usart is disabled, what gives? The Rx and Tx pins on the 628 have multiple functions. To select the Rx and Tx function you need to set this bit. It is kind of like selecting between input and output by setting or clearing the bit in the tris register. Look at Figures 12.5 and 12.8 for pictorial descriptions of the function of SPEN. Regards Sergio Masci http://www.xcprod.com/titan/XCSB - optimising PIC compiler FREE for personal non-commercial use |
Reply by ●November 16, 20042004-11-16
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Don't know how I missed the bit about SYNC - it is required. However, it is cleared at RESET and unless set somewhere else, it shouldn't need to be touched. I find tables 3-1,2,3 & 4 quite helpful in determining initial conditions as well as naming and locating register and bits within registers. Yes, banksel, pagesel, bankisel are quite useful in that they help document exactly which bank/page is being selected and, to some extent, why. All of the various bits are given names in the include file. I personally prefer using the bit name to the bit number. |
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Reply by ●November 16, 20042004-11-16
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yes, table 3-1 and 3-2 are indispensable too bad adobe won't let you split a page, I'm forever switching between indexes and pages, etc., etc., not just for pic's but mysql and others. the php manuals are way cool, totally interactive, very easy to work with online. The pic style manuals are easiest to work with when printed and bound, IMO. , --- In , "rtstofer" <rstofer@p...> wrote: > > > Don't know how I missed the bit about SYNC - it is required. > However, it is cleared at RESET and unless set somewhere else, it > shouldn't need to be touched. > > I find tables 3-1,2,3 & 4 quite helpful in determining initial > conditions as well as naming and locating register and bits within > registers. > > Yes, banksel, pagesel, bankisel are quite useful in that they help > document exactly which bank/page is being selected and, to some > extent, why. > > All of the various bits are given names in the include file. I > personally prefer using the bit name to the bit number. |
