Nokia Color Display

Archive SparkFun Site Questions/Comments
1

So I see that the Nokia color displays are in …

Does the controller chip come with this display? Any implementation suggestions to get this display working with gumstix, microcontroller, serial interface, etc?

What did you use to generate the test screens?

2

Hey,

We used our new favorite - the LPC2138 to generate the online pictures. The example code is posted as well.

The LCD comes with a built-in controller. It only requires a few wires to implement an SPI type interface.

-Nathan

3

Hi all,

I’m using an AT91SAM7S64 based board connected to the Nokia “knock-off” LCD and carrier board bought from Sparkfun. I’m seeing large variations in brightness (flickering on the display)… This was reduced somewhat by adding the 100 uF cap provided by Sparkfun with the carrier board, but I still feel that the flickering is beyond acceptable levels. :frowning: I’ve increased the cap to a 4700 uF low ESR cap… It helps a great deal, but it doesn’t eliminate the flickering. I’ve emailed Sparkfun and had no replies… Anyone else seeing this?

The code is stock off of their site. I’m about ready to bypass the 6.8V from the TPS61040 boost regulator on the carrier board with an LDO to see if it helps. Looking for some feedback…

Thanks

4

We have been working to resolve this problem. Different shipments of the screens from China seem to be more sensitive to noise than others, so when we thought we had a fix, it popped up again.

The problem originates from noise from the booster circuit. If you probe any of the power pins (Vdsp, Vdig) you will see a large amount of high frequency noise. A capacitor as close as possible to the display connector connecting Vdsp to ground helps suppress some of this, but I still measure it to be quite high (>50 mV). We are working on a revision of this circuit to eliminate this noise.

In the meantime, 2 approaches may be taken:

  1. remove all 3 solder jumpers and power the screen from a 3.3 volt supply to Vdig and Vdsp, and a 6-7 volt supply to +LED. This bypasses the backlight booster.

  2. remove solder jumpers JC1 and JC3 and use two separate 3.3 volt supplies, one to Vin which gets stepped up for the backlight, and one to Vdig and Vdsp which powers the screen. This separates the noisy backlight circuit from the screen supply.

Thanks,

Owen