IMXRT1050 Flex IO MCU LCD 8080, WR resting low

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IMXRT1050 Flex IO MCU LCD 8080, WR resting low

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Contributor IV

I'm trying to get an 8080 MCU LCD working on the FlexIO interface on an IMXRT1050. It looks like data is clocking out correctly for the most part however I'm having trouble with the WR and RD pins. They are resting low, then rising just before clocking out data. So I'm getting extra zeros in my data stream. Any ideas?

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NXP TechSupport
NXP TechSupport

Hi Luke,

 

This looks like a very custom approach. It will totally depend on your FlexIO configuration. I highly recommend you to check the below community document. Even though the document is for KL43 devices, the FlexIO modules works the same in RT devices.

 

https://community.nxp.com/docs/DOC-105640 

 

Hope it helps!

 

Best regards,

Felipe

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Contributor IV

So what is causing my issue is that the value on my RW pin is changing when FLEXIO_MCULCD_SetSingleBeatWriteConfig(base) is called and then dropping again when FLEXIO_MCULCD_ClearSingleBeatWriteConfig(base) is called.

One option I've tried is to refactor FLEXIO_MCULCD_WriteCommandBlocking to set the config first, the pin rises, then call FLEXIO_MCULCD_StartTransfer(base) so my CS pin gets set. Then do the opposite at the end of the function. This way my lcd driver should ignore those extra transitions on the WR line.

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I would also need to do similar refactoring for the other read/write functions.

Although I should mention that I am measuring these signals straight out of the MCU and one of my coworkers mentioned that the LCD Driver may hold these lines up anyway and this whole issue will be moot.

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NXP TechSupport
NXP TechSupport

Hi Luke,

 

There is some material that I can recommend you to take as reference.  You can find driver and demo project in the SDK package of a board supports the demo, such as FRDM-K28F. Unfortunately, we do not have this example for RT1050 devices but you can take it as reference.

 

In addition, I suggest you to check this application note that explains how to use the FlexIO module to emulate 8080 bus interface. Also this link mentions the typical usage of FlexIO LCD APIs.

 

I hope this information helps you.

 

Best regards,

Felipe

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