Discussion in "PIC Microcontroller Discussion" started by    sairfan1    Aug 9, 2014.
Sat Aug 09 2014, 10:42 am
#1
Hi,
I have some TFT 3.2" (driver SSD1289, HX8352 and ILI9481) as these all have 16bit interface. after spending hours still i could not find out how can i interface it in 8 bit mode, in datasheet i read that it can be connected in 8 bit mode and even in serial mode, but did not find any instruction or command. Please help if any one have tried it. thanks
Sat Aug 09 2014, 09:16 pm
#2
LCDs in market are customized by vendors and they usually configure controllers in 16-bit 8080 MCU format. Most of vendors keep provision of resistor based bootstrap on flex strip of LCD to change the modes of these LCD controllers. So instead of looking into datasheet of controllers look into datasheet of LCD and find out where you can locate those resistors. One more thing to note is, when you're changing mode like you want to use serial mode then make sure those serial pins are coming out on flex connector
 sairfan1 like this.
Sat Aug 09 2014, 11:16 pm
#3
Thanks a lot, i did not get such a useful information on this issue. unfortunately it is very hard to find datasheet for a china based item, even i have experience of wrong datasheet provided by supplier, so one have to pay hours of work to solve such mystery.

While reading datasheets its feel like TFT is configured for 16/8/3bit mode by command?

I'm attaching image of my TFT please see if you have gone through such kind.



[ Edited Sat Aug 09 2014, 11:21 pm ]
Mon Aug 11 2014, 09:44 pm
#4
I had similar bad experience with Chinese vendors. Data sheet was not matching controller specs and then finally it was vendor's mistake providing invalid information in their LCD datasheet.

This TFT LCD is different from what I worked on and I suggest you need to look on the other side of PCB where LCD is mounted and connected, incase you want to try changing its mode. I do not recommend doing that unless you have a good information of complete module. I am not sure if you can take off the LCD and see whats underneath and find out if you can still modify this to work in different mode.

The pinouts shows LCD is configured to run in parallel mode. There are many arduino based libraries available specially for this LCD. Did you check that?
Tue Aug 12 2014, 12:53 am
#5
Thanks, I have successfully run the TFT in 16bit mode, i am using PIC controller after connecting TFT and Touch panel i'm left with no available ports. thats why it is necessary for me to configure it at least in 8bit mode.

I pulled out TFT to see its back side, please refer to attached image and advise if it can be configured.

One more thing I'm running project in 3.3v, i have added 40ohm resistor to its LEDs, it does not look like enough bright. Please advise how much resistance can be decreased to get brighter picture.

Thanking you.

Tue Aug 12 2014, 12:56 am
#6
i was unable to upload image from front side, here is link to view

Image


[ Edited Tue Aug 12 2014, 01:05 am ]
Wed Aug 13 2014, 01:12 am
#7
I could not figure out much from the images. I think you're currently out of luck with changing LCD mode. however you can do other things to save pins of your controller like using a shift register to make a 16-bit port out of just 3 pins e.g. CD4094 you can connect two CD4094, feed data to only one shift register the next shift register can be connected back to back feeding Qs pin of first shift register to data pin of the next one and clock is common to both. once the data is shifted you can enable latch so all data is available on parallel port at once to avoid any error data.

Now you can do simple bitbang with a for loop to shift out 16-bits. this way with just three pins can give you a full 16-bit port.
Wed Aug 13 2014, 01:29 am
#8
thanks, finally advise about brightness issue, I'm running project in 3.3v, i have added 40ohm resistor to its LEDs, it does not look like enough bright. Please advise how much resistance can be decreased to get brighter picture.

And which Touch TFT model/driver do you recommend, if possible plz give refer to some image. Thanks again.
Wed Aug 13 2014, 02:04 am
#9
Usually its better to have a LED driver circuit in place for TFT backlights which can supply constant current. and then depending on forward voltage of LEDs you can decide series resistor. For this datasheet is more helpful to find out forward drop voltage of backlight LEDs.

Recommended modules.. I cannot say much on that as most of modules in market are mostly same. You can try TFTs from New Haven display, they are a reliable source, maybe a bit costly. I will see if i can get you better vendor name for TFTs.
Wed Aug 13 2014, 11:18 pm
#10
thanks, will be waiting for.

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