320(rgb)x240 lcd
DaveC3
Posts: 8
I am new to the Propeller, however I have been programming PIC micros for many years. I acquired a couple of 320(RGB)X240 displays for a buck a peace. They do not have a controller chip. So far I have been able to modify R. A. Paz Schmidt's LCD.spin (thanks for the kick start) to display color bars. Now I am stuck. I want to be able to display text and graphics on this display. I have ordered the Hydra book (maybe this will point the way).
Here are the signals that I need to control
Any help would be appreciated
Thanks
Dave
Here are the signals that I need to control
Frame = High during the first scan line
Load = a pulse after each scan line
CP = clock pulse
DISP = turn on display high signal
VEE = turn on lcd drive voltage ~27v high signal
Data = one byte
[noparse][[/noparse]code]
KCS057QV1AD RGB Display connected to 74LCX245 (as buffer 3.3v to 5v logic):
PIXEL 1 2 3 4 5 6 7 8 ............. 320
D0..D7 PA0..7 Data RGBRGBRG BRGBRGBR GBRGBRGB ............
bit 76543210
' dec val 146 73 36
'Red %10010010_01001001_00100100
' 73 36 146
'Green %01001001 00100100 10010010
' 36 146 73
'Blue %00100100 10010010 01001001
' 182 219 109
Any help would be appreciated
Thanks
Dave
Comments
Displaying text and graphics on the Propeller is divided into two parts: drawing and displaying. For the drawing part, you'll probably use the Graphics object. It has methods for drawing lines, text, etc. It does its work on a bitmap. To actually display the bitmap, you'll use a TV object if you're hooked up to a TV, a VGA object if you're connected to a VGA monitor, or in your case, well, you're out of luck.
The Propeller doesn't have built-in support for 24-bit pixels, so you've got your work cut out for you. Maybe you could use the VGA driver to start with. It outputs 6 bits per pixel, 2 each for R, G, B. Connect them to the most-significant bits of your LCD's RGB inputs. You still have to figure out the sync signals.
Eventually you'll have to get into assembly language and devote a cog (or two?) to pumping out pixels.
Probably from SparkFun. They sell a Color QVGA 2.3" 320x240 for $1USD. Sku is LCD-08843.
Cheers,
Alex
As I said I am real new to the propeller. I will do some more reading on the video and VGA drivers to see if I can modify something.
Each pixel has three bits (RGB) but the data bus is eight bits wide so I have to figure out how to get 2 & 2/3 pixels per byte.
Thanks for the reply's
Dave
What I think you have is a Color STN display. or I'm wrong ?. This displays make up the colors using frame dithering, That means that to get shades of a color use set a pixel in one frame and do not set in subsequent frames. Very complicated. Why they do not have 6 or 9 data pins is everybody's guess.
The easiest way to drive it would be to use full colors, just one shade of any color. And build a table depending which pixel you are driving because after some pixels you start over with the combination:
1st byte : RGB RGB RG
2nd byte : B RGB RGB R
3rd byte : GB RGB RGB
4th byte : RGB RGB RG
...
As you see after 3 bytes the scheme repeats. So you have 2 solutions, either you have a 27kbytes buffer in memory and use 1 shade of each color (8 colors) and have the bitmap in memory with exactly this structure (easy to drive the display because you only send the data as they are in memory.
2nd: You reorder the data from memory before you send it to the display. Well... There is not enough memory to use say 4 bits per pixel because that would mean more than 32k for he buffer.
Well try the first approach
How to draw something ?, well each pixel occupies 3 bits so you have to calculate in bits and then get the byte and bit index out of the x and y coordinates. Not utterly complicated.
If it is a TFT display... the driving will be different, but with your : it has 8 bits and 1 per color sounds like a CSTN.
Have fun and if you have more questions, here we are.
Ale
Thanks for the reply. I have been able to make full screen one color, different color bars and and split screen with different colors. I used the method you suggested by making 3 bytes in a specific color pattern. That gives eight pixels for three bytes of data.
I will try your suggestion #1
And thanks again for posting lcd.spin it was a great help getting started.
Dave
Here is a picture of the display and the various supporting boards. To the far right you can see the Propeller USB board, just to the left of that is a 3,3v to 5v adapter. I used two 74LCX245's. Jut to the lft of that is a small board that has the 5v to 27v biasa supply and supplies 5v to the display as well as all the LCD connections. As you can see I can ge te display to produce color bars. In this case red, green, blue.
Here is the code.
KCS057QV1AD RGB Display connected to 74LCX245 (as buffer 3.3v to 5v logic): PIXEL 1 2 3 4 5 6 7 8 ............. 320 D0..D7 PA0..7 Data RGBRGBRG BRGBRGBR GBRGBRGB ............ DISPON PA11 bit 76543210 CP PA10 LOAD PA9 FRM PA8 VEE PA12 ' 146 73 36 'Red %10010010_01001001_00100100 ' 73 36 146 'Green %01001001 00100100 10010010 ' 36 146 73 'Blue %00100100 10010010 01001001 ' 182 219 109 'R&B %10110110 11011011 01101101 ' 73 146 36 '/BLUE %01001001_10010010_00100100 ' 36 73 146 '/RED %00100100_01001001_10010010 /GREEN %10010010_00100100_01001001 } 'Constants to be located here '*************************************** ' System Definitions '*************************************** _OUTPUT = 1 'Sets pin to output in DIRA register _INPUT = 0 'Sets pin to input in DIRA register _HIGH = 1 'High=ON=1=3.3v DC _ON = 1 _LOW = 0 'Low=OFF=0=0v DC _OFF = 0 _ENABLE = 1 'Enable (turn on) function/mode _DISABLE = 0 'Disable (turn off) function/mode _BLACK = %00000000 _WHITE = %11111111 '************************************** '*************************************** ' LCD Interface to Propeller '*************************************** ' _LCD_Data = 7..0 ' Data lines (This line is here for reference, not for code) _LCD_FRM = 256 'Synchronous signal for driving scanning line _LCD_LOAD = 512 'Data signal latch clock _LCD_CP = 1024 'Data signal shift clock _LCD_DISP = 6144 'Display control signal and VEE on 'k_FRM = 256 'k_LOAD = 2 'k_CP = 4 'k_DISP = 8 'k_VEE = 16 k_SHL = 256 k_GRAPH = $8000 - 320*240/8 ' 0x3500 k_TEXT = k_GRAPH - 320*240/48 k_GRAPHD = k_TEXT - 1 k_FONT = $8000 PUB start cognew(@cog1start, 0) cognew(@cog2start, 0) repeat DAT cog1start mov OUTA,#0 mov DIRA,cnt_dira mov _cont,#0 ' resets frame counter ' waveform: ' ' CP is used on the falling edge to transfer data ' FRM is high during the first line before to after the last column group ' LOAD is used at the end of last column to load the data refresh_main mov _a,#240 ' line counter cmp _cont,#0 wz if_nz mov _touta,cnt__LCD_DISP ' turns on VEE if_z mov _touta,cnt__LCD_FRM ' mov _y,#0 'reset y refresh mov OUTA,_touta or _touta,cnt__LCD_CP ' reises clock mov _b,#40 ' column counter ' mov _x,#0 ' reset x ref_line call #color ' get color of pixals from cog2 ' now we send the data to the display mov _d,_c ' put color data in d and _d,cnt_dout ' and color with %00000000_00000000_00000000_11111111 or _d,_touta mov OUTA,_d ' outputs data and clock shr _c,#8 ' shifts data andn OUTA,cnt__LCD_CP ' resets clock mov _d,_c and _d,cnt_dout or _d,_touta mov OUTA,_d ' outputs data and clock shr _c,#8 ' shifts data andn OUTA,cnt__LCD_CP ' resets clock mov _d,_c and _d,cnt_dout or _d,_touta mov OUTA,_d ' outputs data and clock andn OUTA,cnt__LCD_CP ' resets clock ' add _x,#8 ' add 8 pixels to x djnz _b,#ref_line ' Decrement colume cpunter and jump to ref_line if not zero mov _b,CNT add _b,#40 ' wait 1 us waitcnt _b,#80 or OUTA,cnt__LCD_LOAD waitcnt _b,#84 andn OUTA,cnt__LCD_LOAD waitcnt _b,#0 andn _touta,cnt__LCD_FRM andn OUTA,cnt__LCD_FRM ' djnz _a,#refresh add _cont,#1 jmp #refresh_main ' another _a long 0 _b long 0 _c long 0 _d long 0 _t long 0 _cont long 0 ' frame counter, used to activate negative voltage _ptr long 0 _touta long 0 _toutb long 0 cnt_dout long %00000000_00000000_00000000_11111111 cnt_dira long %00000000_00000000_00011111_11111111 contr_out long %00000000_00000000_00011111_00000000 contr_dir long %00000000_00000000_00011111_00000000 cnt_50ms long 50*80_000 cnt_AA long $10101010'20202020'40404040'30303030'60606060'c0c0c0c0 cnt__LCD_CP long _LCD_CP<<k_SHL cnt__LCD_FRM long _LCD_FRM<<k_SHL cnt__LCD_LOAD long _LCD_LOAD<<k_SHL cnt__LCD_DISP long (_LCD_DISP<<k_SHL)|(_LCD_FRM<<k_SHL) ' turn on VEE cnt_RED long %00100100_01001001_10010010 cnt_BLUE long %01001001_10010010_00100100 cnt_WHITE long %11111111_11111111_11111111 cnt_BLACK long %00000000_00000000_00000000 cnt_GREEN long %10010010_00100100_01001001 ' fit DAT cog2start color cmp _a,#80 wc if_b mov _c,cnt_BLUE if_a mov _c,cnt_GREEN cmp _a,#160 wc if_a mov _c,cnt_RED ' jmp #color ' cmp _x,#160 wc ' if_a mov _c,cnt_RED ' cmp _x,#120 wc 'if_a mov _c,cnt_WHITE 'if_b mov _c,cnt_WHITE color_ret ret red long %001 green long %010 blue long %100 _t0 byte 0 _t1 long 0 _t2 long 0 _t3 long 0 _x long 0 _y long 0 _chptr long 0 _dptr long 0 _str long $2a0 cnt_k2_FONT long k_FONT cnt_k2_GRAPH long k_GRAPH cnt_80m32 long 80*32-2There is a bunch of stuff that is not needed, just been to lazy to take it out.
Thanks
Dave
Wowsers, that 320x240 LCD is bigger than I thought; formerly I thought you were talking about a Nokia cell phone LCD.
Good eye, yes it is most likely the same supply. I bought two or three from Tanner electronics in Dallas. I do not remember what I paid for them but not more than $10 more likely in the $5 range(I am cheap). I use the one in the picture for my bench supply.
I picked up this display in Austin. They were a real bargain, $1.00 each. They did not have any data on them so I did a search and gave them the data sheet, they gave me another for free. Up to now I have not thought it possible to run the display (in a useful manner). I normally build my projects around PIC Micros. It would be very hard to do it with a PIC and using a non-asm programing language. I thought the Propeller looked like it could handle the job so I sent for one a couple of weeks ago. Now I have to learn another language
Take care
Dave