by Joe Colquitt
Copied with permission from
http://home.clear.net.nz/pages/joecolquitt/bmp2lcd.html
This board is also used for
Text
to graphic LCD using PIC 18F
A .BMP image can be converted fairly easily for display on a graphic LCD.
The
example here is for a 1-bit colour depth (ie black/white) 128 x 64 image
Here are a couple of pages describing the BMP format
fileformat.com
fortunecity.com
The important things to remember for this conversion are that the BMP is
stored in
memory 'upside-down'and that there are 1024 data bytes. For this known size
and
colour depth, the header information can be ignored
The LCD screen used is the Agena AG1286401
ag1286401
which has two KS0108 controllers
ks0108
The example above was drawn with Paint Shop Pro, 2 colours (1-bit), 128 x
64, black
background, which is actually an inverse image on the PC monitor
Circuit for this s/w
This particular screen needs -10V for Vo, and pins 3 and 18 are connected
on the PCB. It
has pads for a voltage inverter (Epson SCI7661) but that's not installed,
so Vo has to be made,
in this case with an MC34063 SMPS IC. Not the only or cheapest way, but parts
were handy.
PCB artwork (I use 600dpi laser toner transfer) and overlay at the bottom
of this page.
I should have transposed the PortC and DB0-7 connections, but instead added
a s/w mirror.
The screen is drawn in the schematic to show that there are 16 distinct areas
on it. The
KS0108 for each half controls 8 pages. Each page is 8 bits high by 64 bits
wide
Layout - BMP vs LCD
The difference is that a BMP line is bytes stacked end-to-end, ie sequentially
in memory. The
same line on an LCD is made of the same bit numbers (ie 0 - 7) of a column
of bytes
So, the method to convert BMP data to LCD data is to rotate an array of 8
x 8 pixels
Consider this pattern in a 16 x 8 (two 8x8 blocks) section of a BMP
Line 0 starts FF, 7F and then 14 bytes to the end of the line at byte015
Line 1 starts 83, 01 and then etc
Line 2 starts A1, 81 and then etc
What's needed to be done is 'vertically slice' that picture, effectively
rotating the data
and converting it to the LCD format.
Taking it column by column, these are data values that will be stored in
'array'. The s/w
does this on each 8x8 pixel block, working across the BMP data
bit7 of byte000 becomes bit0 of byte00, bit6 of byte001 becomes bit0 of byte01
etc
bit7 of byte016 becomes bit1 of byte00, bit6 of byte016 becomes bit1 of byte01
etc
My data is sourced from a USB drive through the Data/Clock lines (you could
of course bit-
bang or upload via the UART or type data directly into a look-up table),
and stored from
0x0100 (bmp_base) onwards. Note that because the BMP data comes starting
with line
63 and ends with line 0 that it's 'upside-down' in memory. The s/w therefore
works
backwards, starting with the block of 128 bytes (= 128 * 8 pixels = 2 pages,
1 left, 1 right)
beginning at 0x0480 and ending at 0x04FF
Left page 0 Right page 0
0x0480 - 0x0487 0x0488 - 0x048f
0x0490 - 0x0497 0x0498 - 0x049f
0x04a0 - 0x04a7 0x04a8 - 0x04af
0x04b0 - 0x04b7 0x04b8 - 0x04bf
0x04c0 - 0x04c7 0x04c8 - 0x04cf
0x04d0 - 0x04d7 0x04d8 - 0x04df
0x04e0 - 0x04e7 0x04e8 - 0x04ef
0x04f0 - 0x04f7 0x04f8 - 0x04ff
cblock 0x0000
array:64 ;64 RAM bytes = 1 LCD page
endc
; lata,0 ;spare
; lata,1 ;spare
; lata,2 ;spare
#define cs1 lata,3 ;CS1
#define cs2 lata,4 ;CS2
#define lcd_rst lata,5 ;/Reset
;LCD pins 0V V+ VO RS R/W En DB0-DB7 CS1 CS2 /Reset Vee A K
#define en latb,0 ;LCD
#define rw latb,1 ;LCD
#define rs latb,2 ;LCD
#define led latb,3 ;LED
#define bbclk portb,4 ;input clock
#define bbdata portb,5 ;input data
; latb,6 ;spare
; latb,7 ;spare
;PortC 0-7 - LCD data, mirrored
#define busy portc,3
;per KS0108 datasheet
page_base = 0xb8 ; + 0 - 7
y_base = 0x40 ; + address 0 - 63, pixel position on line
line_base = 0xc0 ; + line 0 - 63, not needed for this
bmp_base = 0x0100 ;data storage RAM address
;================================================
; Extract data and display
;================================================
;One page of pixels is 8 high x 64 wide = 64 bytes
;BMP in PIC memory is in reverse line scan order, ie picture is inverted
;in original BMP file format
; M L
; S S
; b b
;line 63 (a63) 76543210 (b63) 76543210 (c63) 76543210 etc, 16 bytes wide @ 0100
;line 62 (a62) 76543210 (a62) 76543210 (c62) 76543210 etc, 16 bytes wide @ 0120
;......
;line 01 (a01) 76543210 (b01) 76543210 (c01) 76543210 etc, 16 bytes wide @ 04e0
;line 00 (a00) 76543210 (b00) 76543210 (c00) 76543210 etc, 16 bytes wide @ 04f0
;On KS0108 screen, one page is 8 vertical bytes * 64 columns
;8 bytes sent to LCD are made of the bit7's, bit6's, bit5's etc
; b b b b b b b b b b
; y y y y y y y y y y
; t t t t t t t t t t
; e e e e e e e e e e
; 01 02 03 04 05 06 07 08 09 10
;a56 7 a56 6 a56 5 a56 4 a57 3 a56 2 a56 1 a56 0 b56 7 b56 6 etc
;a57 7 a57 6 a57 5 a57 4 a58 3 a57 2 a57 1 a57 0 b57 7 b57 6 etc
;a58 7 a58 6 a58 5 a58 4 a59 3 a58 2 a58 1 a58 0 b58 7 b58 6 etc
;a59 7 a59 6 a59 5 a59 4 a60 3 a59 2 a59 1 a59 0 b59 7 b59 6 etc
;a60 7 a60 6 a60 5 a60 4 a61 3 a60 2 a60 1 a60 0 b60 7 b60 6 etc
;a61 7 a61 6 a61 5 a61 4 a62 3 a61 2 a61 1 a61 0 b61 7 b61 6 etc
;a62 7 a62 6 a62 5 a62 4 a62 3 a62 2 a62 1 a62 0 b62 7 b62 6 etc
;a63 7 a63 6 a63 5 a63 4 a63 3 a63 2 a63 1 a63 0 b63 7 b63 6 etc
;128 pixels per line = 16 bytes a - p
;line 00 (a00) 76543210 (b00) 76543210 (c00) 76543210 ... (p00) etc, 16 bytes wide @ 04f0
;line 01 (a01) 76543210 (b01) 76543210 (c01) 76543210 ... (p01) etc, 16 bytes wide @ 04e0
;line 02 (a02) 76543210 (b02) 76543210 (c02) 76543210 ... (p02) etc, 16 bytes wide @ 04d0
;line 03 (a03) 76543210 (b03) 76543210 (c03) 76543210 ... (p03) etc, 16 bytes wide @ 04c0
;line 04 (a04) 76543210 (b04) 76543210 (c04) 76543210 ... (p04) etc, 16 bytes wide @ 04b0
;line 05 (a05) 76543210 (b05) 76543210 (c05) 76543210 ... (p05) etc, 16 bytes wide @ 04a0
;line 06 (a06) 76543210 (b06) 76543210 (c06) 76543210 ... (p06) etc, 16 bytes wide @ 0490
;line 07 (a07) 76543210 (b07) 76543210 (c07) 76543210 ... (p07) etc, 16 bytes wide @ 0480
;.....
;line 62 (a62) 76543210 (b62) 76543210 (c62) 76543210 ... (p62) etc, 16 bytes wide @ 0110
;line 63 (a63) 76543210 (b63) 76543210 (c63) 76543210 ... (p63) etc, 16 bytes wide @ 0100
;To make 64 Page0 bytes
;
; LSb MSb
;
;byte1 = a00,7 + a01,7 + a02,7 + a03,7 + a04,7 + a05,7 + a06,7 + a07,7
;byte2 = a00,6 + a01,6 + a02,6 + a03,6 + a04,6 + a05,6 + a06,6 + a07,6
;...
;byte8 = a00,0 + a01,0 + a02,0 + a03,0 + a04,0 + a05,0 + a06,0 + a07,0
process bsf cs1 ;do left-hand side
usec ;1us delay
bcf cs2
usec
movlw line_base
call write_c
call convert
bcf cs1 ;do right-hand side
usec
bsf cs2
usec
movlw line_base
call write_c
movlw 0x88 ;half-way across screen
call right
return
;start retrieval from end of RAM (0x0480 block)
convert movlw 0x80 ;add to source RAM base address, 0x0100
right movwf block_lo
movlw 0x03
movwf block_hi
clrf page_no ;LCD page, 0 - 7
extract call clrpage ;erase page array, 0x0000 - 0x003f
movlw page_base ;0xb8
clrc
addwf page_no,w ;0 - 7
call write_c ;set page number to work on
clrf column ;position of BMP data on the screen line
clrf byte
movlw .8 ;bit counter
movwf loop_cnt
next_col lfsr fsr0,bmp_base ;RAM base address
movfw block_lo ;make actual source address
clrc
addwf fsr0l
movfw block_hi
clrc
addwf fsr0h
movfw column ;byte position along line
clrc
addwf fsr0l ;in current 8 lines of data
;in that block of data -
; ;480 - 8th line of BMP, all the bit0s array bytes
; ;490 - all the bit1s "
; ;4a0 - all the bit2s "
; ;4b0 - all the bit3s "
; ;4c0 - all the bit4s "
; ;4d0 - all the bit5s "
; ;4e0 - all the bit6s "
; ;4f0 - top line of BMP all the bit7s "
loop8 lfsr fsr1,array ;64 bytes starting at 0x0000
movfw byte ;set to start of page array
clrc
addwf fsr1l
movff fsr1h,temp1 ;save FSR1
movff fsr1l,temp0
movfw indf0 ;fetch BMP data byte
btfsc wreg,7 ;set its bits in corresponding page array bytes
bsf indf1,0
incf fsr1l
btfsc wreg,6
bsf indf1,0
incf fsr1l
btfsc wreg,5
bsf indf1,0
incf fsr1l
btfsc wreg,4
bsf indf1,0
incf fsr1l
btfsc wreg,3
bsf indf1,0
incf fsr1l
btfsc wreg,2
bsf indf1,0
incf fsr1l
btfsc wreg,1
bsf indf1,0
incf fsr1l
btfsc wreg,0
bsf indf1,0
movff temp1,fsr1h ;restore FSR1
movff temp0,fsr1l
dcfsnz loop_cnt
bra rot_done ;do only 7 rotates
rlncf postinc1 ;rotate the bits through the 8 array bytes
rlncf postinc1
rlncf postinc1
rlncf postinc1
rlncf postinc1
rlncf postinc1
rlncf postinc1
rlncf postinc1
movlw .16 ;next BMP line
clrc
addwf fsr0l
bra loop8
rot_done incf column ;next column of BMP bytes
movlw .8 ;reset counter
movwf loop_cnt
movlw .8 ;storage to be in next 8 array bytes
clrc
addwf byte
btfss byte,6 ;8 bytes on 8 lines processed
bra next_col ;no, next column of 8 BMP bytes
;---------------------
display movlw y_base ;left-most
call write_c
movlw page_base ;set LCD page that data is for
clrc
addwf page_no,w
call write_c
lfsr fsr0,array
do64 movfw postinc0 ;write 64 bytes to screen
call write_d
btfss fsr0l,6
bra do64
;---------------------
movlw 0x80 ;move backwards through RAM by 1 block
subwf block_lo
skpc
decf block_hi
incf page_no
btfss page_no,3 ;8 pages done
bra extract
return
;---------------------
;clear page buffer
clrpage lfsr fsr0,array
lp64 clrf postinc0
btfss fsr0l,6 ;64 bytes cleared
bra lp64
return
;================================================
; Write data
;================================================
write_c bcf rs ;write command
bra d_out
write_d bsf rs ;write data
d_out movwf swap_d
clrf temp2
bcf rw
movlw .8 ;mirror data for port
movwf dcnt1
swap btfsc swap_d,0
bsf temp2,7
rlncf swap_d
rrncf temp2
decfsz dcnt1
bra swap
d0 movff temp2,latc ;write to port
usec
bcf en
usec
bsf en
usec
bcf rs
usec
bsf rw
usec
mov b'00001000',trisc
btfsc busy
bra $-2
mov b'00000000',trisc
bcf rw
usec
return
;================================================
; Clear all PIC RAM
;================================================
clr_ram lfsr fsr0,0x000
lfsr fsr1,0x100
lfsr fsr2,0x200
clear1 clrf postinc0
clrf postinc1
clrf postinc2
btfss fsr0h,0
bra clear1
lfsr fsr0,0x300
lfsr fsr1,0x400
lfsr fsr2,0x500
clear2 clrf postinc0
clrf postinc1
clrf postinc2
btfss fsr0h,2
bra clear2
return
;================================================
; Clear all screen RAM
;================================================
clearall movlw page_base
call write_c
movlw y_base
call write_c
movlw line_base
call write_c
reload movlw .64
movwf cnt1
show0 movlw 0x00
dispw
decfsz cnt1
bra show0
incf page_no
btfsc page_no,3
bra clr_done
movfw page_no
addlw page_base
call write_c
bra reload
clr_done return
