Post by thread:Code Problem... What is wrong?

Hello EveryOne, I've written a piece of code... But unfortualy it doen not work right... The 16c84 communicates with 3 CD4094 IC's. (Serial to parrallel). The error MUST be in the hef4094 routine, but i can't finft the error... Who can find the problem? (-----Cut----) SendOne bsf DATA call wait bsf CLOCK call wait bcf DATA nop bcf CLOCK return SendZero bcf CLOCK call wait bsf CLOCK call wait bcf CLOCK return hef4094 movwf txbyte movlw 0x07 movwf bitcount Sendbit btfss txbyte, bitcount ; Skip next line if bit is set. call SendZero ; Sends a 0 call SendOne ; Sends a 1 decfsz bitcount,1 ; Decrement bitcount, SKip if Zero goto Sendbit return (----Cut-----) main movlw 0xFF call hef4094 movlw 0x00 call hef4094 movlw 0x00 call hef4094 goto main end This piece of code should make 8 of the 24 bits high... But when I look at the outputs of the CD4094 it isn't... He problably sends one Bit to much or something... Greetz, Radboud Verberne. ICQ: 918640 (I Seek You) AX25: spam_OUTNL1DDUTakeThisOuTNL3SMG.NBO.NLD.EU (27.405Mhz) PE1RUH@PI8SHB.#NBO.NLD.EU (144.925Mhz) Yes! I've succeeded my Radio Examenation! My call is PE1RUH! I've rebuilt a Teletron T813 and i'm most of the time QRV on 145.2125 or 145.7000 (Relais Eindhoven). S-Mail: Eerste Vijverstraat 6 5258 HR Berlicum, The Netherlands Phone: +31-73-503-4733 "Er is hier niks te doen, maar begin er maar alvast mee..."

At 07:32 PM 1/19/98 +0100, you wrote: {Quote hidden}>Hello EveryOne, > >I've written a piece of code... But unfortualy it doen not work right... >The 16c84 communicates with 3 CD4094 IC's. (Serial to parrallel). The error >MUST be in the hef4094 routine, but i can't finft the error... Who can find >the problem? > >(-----Cut----) >SendOne > bsf DATA > call wait > bsf CLOCK > call wait > bcf DATA > nop > bcf CLOCK > return > >SendZero > bcf CLOCK > call wait > bsf CLOCK > call wait > bcf CLOCK > return > >hef4094 > movwf txbyte > movlw 0x07 > movwf bitcount >Sendbit > btfss txbyte, bitcount ; Skip next line if bit is set. > call SendZero ; Sends a 0 > call SendOne ; Sends a 1 > decfsz bitcount,1 ; Decrement bitcount, SKip if Zero > goto Sendbit > return > >(----Cut-----) > >main > movlw 0xFF > call hef4094 > movlw 0x00 > call hef4094 > movlw 0x00 > call hef4094 > goto main >end > >This piece of code should make 8 of the 24 bits high... But when I look at >the outputs of the CD4094 it isn't... >He problably sends one Bit to much or something... >Greetz, > Radboud Verberne. > Radbound, I believe your biggest problem is trying to use a variable to select the bit number. BTFSS needs a constant for the bit number so what it does is use the address (probably truncated to 3 bits) of the variable <bitcount>. Also, when you call SendZero, it returns and calls SendOne immediately. You might try: Sendbit rrf txbyte,f ;rotate LSB into carry bit btfss STATUS,C ;is it a 0 goto Zero ;yes, send a zero bit call SendOne ;no, send a one bit goto Nextbit ;go check bit counter Zero call SendZero ;go send a zero bit Nextbit decfsz bitcount,f are we done? goto Sendbit return I haven't tested this code or optimized it but it should work. Hope this helps! Greg Maki

>hef4094 > movwf txbyte > movlw 0x07 > movwf bitcount >Sendbit > btfss txbyte, bitcount ; Skip next line if bit is set. > call SendZero ; Sends a 0 > call SendOne ; Sends a 1 > decfsz bitcount,1 ; Decrement bitcount, SKip if Zero > goto Sendbit > return You will never transmit bit 0 using this routine, and it will always transmit an extra 1 bit if you try to send a 0 bit. Also any new data that you send will not appear at the outputs of the 4094 until the next bit send is executed. ie CLOCK = high. Try this..... hef4094 movwf txbyte movlw 0x08 movwf bitcount Sendbit rlf txbyte btfss status,carry goto send0 call SendOne goto OneLess Send0 call SendZero OneLess decfsz bitcount goto Sendbit return Also try this for the SendOne/Zero routine..... ; Clock bit is normally HIGH, so that previous data is already ; at the output gates. SendZero bcf Port(x),DATA ; send 0 bit goto ClkOut SendOne bsf Port(x),DATA ; send 1 bit ClkOut call wait bcf Port(x),CLOCK ; strobe data to latches call wait bsf Port(x),CLOCK ; send data to output pins ; the next instruction depends on how many instructions ; are executed before this routine is called again ; (may not be needed if clock speed is low) call wait return I know you have already tried it, but it's fairly easy to trap errors like these by using MPSIM or MBLAB simulator and single step through the code. Another thing that is sometimes hard, but very necessary, is to make sure the code is compatable with any external devices, or you may suffer many frustrated hours of fruitless debugging. This means a close examination of the device data sheet. Tony For the beginner.... PicNPoke Multimedia 16F84 Simulator Assembler, and Tutorial. Now with PicNPlay circuit simulator. Plus animated Address Mode Tutor. http://www.dontronics.com/picnpoke.html

Radboud Verberne wrote: > SendOne > bsf DATA > call wait > bsf CLOCK > call wait > bcf DATA > nop > bcf CLOCK > return > SendZero > bcf CLOCK > call wait > bsf CLOCK > call wait > bcf CLOCK > return Presumably DATA and CLOCK are defined as a register,bit combination? Non-critical: Why are these routines assymetric? What is that NOP doing there? Why do you need "wait" calls anyway (is the CPU too fast)? Is DATA initialised as clear in case SendZero is called first? > hef4094 > movwf txbyte > movlw 0x07 > movwf bitcount > Sendbit > btfss txbyte, bitcount ; Skip next line if bit is set. How did bitcount get into this line? You can't use a variable as a bit index into another variable (register)! > call SendZero ; Sends a 0 > call SendOne ; Sends a 1 Hey! Since when do you want every zero to be succeeded by a one? {Quote hidden}> decfsz bitcount,1 ; Decrement bitcount, SKip if Zero > goto Sendbit > return > main > movlw 0xFF > call hef4094 > movlw 0x00 > call hef4094 > movlw 0x00 > call hef4094 > goto main If you leave it looping all the time, the output states will be changing so fast you'll never see what they are! (You forgot the strobe function just before the loop.) How about: SendByte movwf txbyte movlw 8 movwf bitcount clockit movlw ck0dt1 ; default data high rlf txbyte ; MSB first convention, alter if needed skcs ; macro movlw ck0dt0 ; C bit zero: alter data to low movwf serio ; write DATA, CLOCK low iorlw ck1dt0 ; add in CLOCK bit movwf serio ; write DATA, CLOCK high andlw ck0dt1 ; clear CLOCK bit movwf serio ; write DATA, CLOCK low decfsz bitcount ; loop 8 times return main movlw ck0dt0 ; initialise clock & data values movwf serio ; write DATA, CLOCK low movlw 0xFF call SendByte movlw 0x00 call SendByte movlw 0x00 call SendByte movlw ck0dt0+strobe ; Strobe movwf serio ; the data goto main Is that all OK? By setting the I/O register with a pure write each time, you can safely ignore read-modify-write problems. The reload of W between every I/O write should be adequate time for the CMOS to settle but if you do need a delay routine, you put the "movwf serio" at the beginning of it and make sure it doesn't alter W. The following doesn't alter W but uses up to three stack locations: dely16 call dely8 dely8 call dely4 dely4 return Cheers, Paul B.