Post by thread:[EE]: Colour LCD screen

Hi everyone, I was given a small 3" (or so) colour display similar to the ones in those handheld TVs. The problem is, all the docs I was given are in Japanese! I've spent a lot of time searching the net and have a vague idea of how it works, but if anyone knows of any good references on RGB inputs for LCD screens, voltage levels, timing diagrams, anything really, I'd appreciate it. Here's what I know about the screen: The display has 9 inputs: 1 through 3: 10 - 20K variable resistor 4: Sync 5: Blue 6: Red 7: Green 8: +5 V 9: GND The RGB inputs run off a Sony V7021 NTSC/PAL to RGB decoder. I'd like to try running this display via a PIC and perhaps a D/A converter (the RGB values appear to be analog). Can anyone help? I can't find any info on the RGB format or on "Sync" -- I thought there were supposed to be two "Sync"s!! Thanks, Todd. __________________________________________________ Do You Yahoo!? Make international calls for as low as $.04/minute with Yahoo! Messenger http://phonecard.yahoo.com/ -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

>Here's what I know about the screen: >The display has 9 inputs: >1 through 3: 10 - 20K variable resistor >4: Sync >5: Blue >6: Red >7: Green >8: +5 V >9: GND >The RGB inputs run off a Sony V7021 NTSC/PAL to RGB >decoder. I'd like to try running this display via a >PIC and perhaps a D/A converter (the RGB values appear >to be analog). Can anyone help? I can't find any info >on the RGB format or on "Sync" -- I thought there were >supposed to be two "Sync"s!! Todd, seems you never did any RGB interfacing at all! Do it this way: Since it came from a CASIO tv, it should be a CGA type of video (15.750 KHz). Get ArcadeOS in http://www.arcadeos.com and configure it to run in an arcade type monitor. It will make your PC run VGA in 15.750 KHz horizontal frequency. Just tie togheter the 2 sync wires (h and v) and connect to your small RGB panel. Of course you can use an old arcade board or a CGA board without any changes. This "one pin" of sync is nothing more than composite sync - H and V sync togheter. ---8<---Corte aqui---8<---- Alexandre Souza spam_OUTtaitoTakeThisOuTterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> 1 through 3: 10 - 20K variable resistor > 4: Sync > 5: Blue > 6: Red > 7: Green > 8: +5 V > 9: GND 1-3 is probably for adjusting the relative brightness of each of the colors. The rest are most likely normal video signals, especially since you said they were fed by some sort of composite video decoder chip. I doubt you'll hurt anything by feeding it normal AC coupled video signals. If it looks very dim, them maybe it's using 5V or something. If anything is non-standard, it will more likely be the sync levels. These could possibly be TTL levels instead of video levels. Again, start with all the standard signals and see if it works. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, .....olinKILLspam@spam@embedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Todd, Many times on RGB the sync is always on the Green signal. Regards, Mike ----- Original Message ----- From: "T.C. Phelps" <tcphelpsKILLspamYAHOO.COM> To: <.....PICLISTKILLspam.....MITVMA.MIT.EDU> Sent: Tuesday, July 31, 2001 7:36 AM Subject: [EE]: Colour LCD screen {Quote hidden}> Hi everyone, > > I was given a small 3" (or so) colour display similar > to the ones in those handheld TVs. The problem is, all > the docs I was given are in Japanese! I've spent a lot > of time searching the net and have a vague idea of how > it works, but if anyone knows of any good references > on RGB inputs for LCD screens, voltage levels, timing > diagrams, anything really, I'd appreciate it. > > Here's what I know about the screen: > > The display has 9 inputs: > > 1 through 3: 10 - 20K variable resistor > 4: Sync > 5: Blue > 6: Red > 7: Green > 8: +5 V > 9: GND > > The RGB inputs run off a Sony V7021 NTSC/PAL to RGB > decoder. I'd like to try running this display via a > PIC and perhaps a D/A converter (the RGB values appear > to be analog). Can anyone help? I can't find any info > on the RGB format or on "Sync" -- I thought there were > supposed to be two "Sync"s!! > > Thanks, > Todd. > > __________________________________________________ > Do You Yahoo!? > Make international calls for as low as $.04/minute with Yahoo! Messenger > http://phonecard.yahoo.com/ > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

A way to check to see if the sync is riding on the green is simple. If you disconnect a color such as green or blue, the display changes color. If you disconnect the green and the sync is riding on it (always the case on RGB signals I've worked on), the entire display will disappear. You might want to verify that the impedance is 75ohms or a high input impedance also. Regards, Mike {Original Message removed}

> > 1 through 3: 10 - 20K variable resistor > > 4: Sync > > 5: Blue > > 6: Red > > 7: Green > > 8: +5 V > > 9: GND > > Many times on RGB the sync is always on the Green signal. Almost certainly not in this case since there is a separate sync signal. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, EraseMEolinspam_OUTTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Reason for mentioning the sync is that my experience is with monitors that take both an external sync source or can use the sync riding on the green. My recommendation is to connect the RGB first and see what happens, it can't hurt. As a matter of fact, I just installed one today by coincidence. The external sync jack was not used as there was a sync riding on the green signal. With the red or blue missing, color was off. With the green missing, display blanked out. It will not hurt the display to incorrectly connect the video signals, they will just look funny or not have a display. On the particular RGB display I replaced today, there was a start up menu allowing input for an analog, a digital, and a composite input. Also, there was a high impedance/75 ohm switch on the back. The high impedance is used with applications of video loop-thru to another monitor, and the 75ohm used when it was the termination. This was a large mil-spec AMLCD display that I just described to you. If you have a small low-cost unit designed for use with a hand held TV, I would first look for a handheld TV that has a similiar display. I'd then look to see if an external video source from a VCR can be connected to it just to satisfy my curiosity. Maybe there is a MIL-STD regarding the LCD display inputs as they all seem to be going that way now. The military standards are available on the internet. Regards, Mike {Original Message removed}