As with the FPGA board previously, the connections are made by soldering standard IDC ribbon cable directly to the glass substrate.
As the PIC will not work from 3.3V, I had to make a power supply for the LCD. For this I used an LM317, is complete overkill but easy and quick. Both LCD supply pins are tied to the output, which is around 3.0V. All four signal lines have 10K resistors in series, to protect the LCD inputs from the 5V signalling of the PIC.
This time the LCD decoupling is taken care of by a 1nF ceramic cap in parallel with a 4.7uF electrolytic, positive side to pad 8 of the LCD, negative to ground. This results in a rock steady image.
My lash-up for testing the PIC. Note the resistors in the signal paths. Crystal frequency is 3.6864MHz, well within the 16F84's maximum of 4MHz.
PIC is continuously writing this rolling, XOR pattern to the display. (Pixel brightness = X co-ord XOR Y co-ord). Refresh rate is a little disappointing at only 2Hz! Next version will be with either a faster PIC, or a PIC with a hardware serial port, or both.
The LCD starts up in 12 bit color mode (12BPP), and I've only made it work successfully in this mode. If you're only going to display text, then 8BPP mode will be adequate and probably much faster.
When using 12BPP mode, call "LCD3510_WritePixelPair" to write two pixels at a time. You pass a pointer to your 6-byte RAM array in the W-register. This procedure uses only the most significant four bits of each byte.
; ; Nokia 3510i colour LCD interface routines ; ; MPASM assembler, PIC16F84 ; ; neil_manc@yahoo.com 11/10/2005 ; ; 11/10 NS Created ; ; list p = 16f84 #include p16f84.inc ; ports and pins for display interface #define NRESET PORTB, 0 #define NCS PORTB, 1 #define SCK PORTB, 3 #define SDA PORTB, 2 ; declarations for exported functions global LCD3510_Initialise global LCD3510_BeginWritePixel global LCD3510_WritePixel global LCD3510_WritePixelPair global LCD3510_CASET global LCD3510_PASET global LCD3510_SET_12BPP global LCD3510_SET_8BPP global LCD3510_Command global LCD3510_Parameter ; local storage lcd_if_data udata _ctr_i res 1 ;_ctr_j res 1 _ctr_n res 1 _ctr_w1 res 1 _ctr_w2 res 1 _s_byte res 1 _c_byte res 1 ; relocatable code starts here lcd_interface code ; look-up table for display initialisation sequence. call with index ; in W reg. each element consists of ; <parameter count> <command code> ; [<parameter> [<parameter [<parameter> ... ]]] _init_seq addwf PCL, f retlw .0 retlw 0xC6 ; initial escape retlw .1 retlw 0xB9 ; refresh set retlw .0 retlw .7 retlw 0xB6 ; display control retlw .128 retlw .128 retlw .129 retlw .84 retlw .69 retlw .82 retlw .67 retlw .15 retlw 0xB3 ; setup greyscale map 0 retlw 0x11 retlw 0x22 retlw 0x33 retlw 0x44 retlw 0x55 retlw 0x66 retlw 0x77 retlw 0x88 retlw 0x99 retlw 0xAA retlw 0xBB retlw 0xCC retlw 0xDD retlw 0xEE retlw 0xFF retlw .1 retlw 0xB5 ; gamma curve set retlw .1 retlw .1 retlw 0xBD ; common driver output retlw .0 retlw .1 retlw 0xBE ; power supply setup retlw .4 retlw .0 retlw 0x11 ; sleep out retlw .2 retlw 0xBA ; voltage control retlw .127 retlw .3 retlw .1 retlw 0x25 ; contrast retlw .70 retlw .20 retlw 0x2D ; colour look up table for 8BPP mode retlw 0x00 ; red (8 levels) retlw 0x02 retlw 0x04 retlw 0x06 retlw 0x09 retlw 0x0B retlw 0x0D retlw 0x0F retlw 0x00 ; green (8 levels) retlw 0x02 retlw 0x04 retlw 0x06 retlw 0x09 retlw 0x0B retlw 0x0D retlw 0x0F retlw 0x00 ; blue (4 levels) retlw 0x05 retlw 0x0A retlw 0x0F retlw .13 retlw 0xB7 ; setup temp gradient retlw .0 ; -.05(n+1)%/K, 0 <= (n) < 4 retlw .0 ; all zeros(?) from here on: retlw .0 ; used during factory testing retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw .0 retlw 0x03 ; booster voltage on retlw 0xED ; end of sequence! retlw .0 retlw 0x21 ; inversion on retlw .0 retlw 0x29 ; display on ; short wait (for debugging) _short_wait clrf _ctr_w2 incf _ctr_w2 clrf _ctr_w1 goto __wait_loop ; waits 50ms (at 4MHz) TODO: find a way of automating this _wait_5ms movlw 70 movwf _ctr_w2 clrf _ctr_w1 __wait_loop decfsz _ctr_w1, F goto __wait_loop decfsz _ctr_w2, F goto __wait_loop return ; exported function: LC3510_Command ; used for sending misc command bytes to the display LCD3510_Command ; sends a command byte to the display. call with command stored in ; W register _command movwf _s_byte ; save W reg ; terminate any prior sequence of parameters bsf NCS bcf SCK ; call __per_cycle_wait bcf NCS ; first bit is zero for command bcf SDA ; call __per_cycle_wait bsf SCK bsf SDA ; data pin high, ready for byte sending goto __send_byte ; exported function: LC3510_WritePixel ; pixel value stored in W register ; writes one 8BPP pixel to display LCD3510_WritePixel ; exported function: LC3510_Parameter ; used for sending misc parameter bytes to the display LCD3510_Parameter ; sends a parameter byte to the display. call with parameter in W ; register _parameter movwf _s_byte ; save W reg bcf SCK ; clock in a one for parameter bsf SDA bsf SCK __send_byte ; unrolled byte serialisation loop bcf SCK btfss _s_byte, 7 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 6 bsf SDA btfss _s_byte, 6 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 5 bsf SDA btfss _s_byte, 5 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 4 bsf SDA btfss _s_byte, 4 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 3 bsf SDA btfss _s_byte, 3 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 2 bsf SDA btfss _s_byte, 2 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 1 bsf SDA btfss _s_byte, 1 bcf SDA bsf SCK bcf SCK btfsc _s_byte, 0 bsf SDA btfss _s_byte, 0 bcf SDA bsf SCK return ; exported function: LCD3510_initialise ; no paramters LCD3510_Initialise bcf STATUS, RP1 bsf STATUS, RP0 bcf NRESET ; set ports to be outputs bcf NCS bcf SDA bcf SCK bcf STATUS, RP0 bcf NRESET bsf NCS bsf SDA bsf SCK call _wait_5ms bsf NRESET movlw 0x01 ; send soft reset call _command bsf NCS call _wait_5ms clrf _ctr_i ; begin display initialisation loop __disp_init_loop movf _ctr_i, W ; get number of parameters call _init_seq movwf _ctr_n incf _ctr_i, F xorlw 0xED ; test for end of sequence btfsc STATUS, Z goto __init_end movf _ctr_i, W ; send command byte incf _ctr_i, F call _init_seq call _command movf _ctr_n, F ; test if n = 0 (no parameters) btfsc STATUS, Z goto __disp_init_loop __init_param_loop ; get each parameter and send to display movf _ctr_i, W incf _ctr_i, F call _init_seq call _parameter decfsz _ctr_n, F goto __init_param_loop goto __disp_init_loop __init_end call _wait_5ms ; time for booster voltage to settle movlw 0x21 ; inversion on call _command movlw 0x29 ; display on call _command bsf NCS ; terminate final parameter sequence return ; exported function: LCD3510_BeginWritePixel ; no parameters LCD3510_BeginWritePixel movlw 0x2C ; write memory command call _command return ; exported function: LC3510_WritePixelPair ; pointer to six-byte array of RGB values stored in W register ; writes two adjacent 12BPP pixels to display LCD3510_WritePixelPair movwf FSR movf INDF, W andlw 0xF0 movwf _c_byte incf FSR, F swapf INDF, W andlw 0x0F iorwf _c_byte, W call _parameter incf FSR, F movf INDF, W andlw 0xF0 movwf _c_byte incf FSR, F swapf INDF, W andlw 0x0F iorwf _c_byte, W call _parameter incf FSR, F movf INDF, W andlw 0xF0 movwf _c_byte incf FSR, F swapf INDF, W andlw 0x0F iorwf _c_byte, W call _parameter return ; exported function: LC3510_CASET ; pointer to two-byte array stored in W register: start column no. ; and end column respectively. LCD3510_CASET movwf FSR movlw 0x2A call _command movf INDF, W call _parameter incf FSR, F movf INDF, W call _parameter return ; exported function: LC3510_PASET ; pointer to two-byte array stored in W register: start row no. ; and end row respectively. LCD3510_PASET movwf FSR movlw 0x2B call _command movf INDF, W call _parameter incf FSR, F movf INDF, W call _parameter return ; exported function: LC3510_SET_12BPP: pixels are packed RRRRGGGGBBBB ; no parameters LCD3510_SET_12BPP movlw 0x3A call _command movlw 0x03 call _parameter return ; exported function: LC3510_SET_8BPP. pixels are packed RRRGGGBB ; no parameters LCD3510_SET_8BPP movlw 0x3A call _command movlw 0x02 call _parameter return end