AN2641 datasheet(33/37 Pages) STMICROELECTRONICS

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AN2641

Troubleshooting

Doc ID 14027 Rev 1

33/37

Troubleshooting

Here are some solutions to common issues that can occur during development of a CLCD

driver.

8.1

Video flickering

Flickering is caused by the CLCD master not having enough bandwidth over the AHB

memory system. In this case you need to configure the priority of the MPMC ports properly.

Solution: The Xloader takes care of this and puts CLCD port at the highest priority.

8.2

Video tearing

When displaying video frames if the rate is not fast enough, then while we can see a new

frame, the disappearing of the old frame can also be perceived by the human eye. Such an

overlapping is known as video tearing.

Solution: In this case you should change the driver implementation and add the dual frame

buffer capability. One buffer will be the current one, while the CPU prepares the second one.

Then the driver should switch the CLCD pointer.

8.3

White screen

If a CLCD application activates the panel at regular intervals then after a certains number of

iterations (this issue has been observed after 20 iternations) a white screen appears and

CLCD hangs unless power down occurs.

Solution: As described in Section 4: Enabling and disabling the CLCD on page 16 , there

two steps required for CLCD activation:

Control signal on

Data signal on.

A small delay (in milliseconds) is required between both to let the control signal stabilize.

AN2641 データシート(PDF) 33 Page - STMicroelectronics