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Can address pin A25 (STM32F765II) be used for LCD 8080 interface in case of 16 bit data?

Yuora
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I am trying create drivers for LCD using 8080 interface and STM32F765II cpu. In order to config the cpu I use STM32CuBeMX and I can select line A25 to switch command/data even when I set 16 bits data bus. But also I found next text in the datasheet:

"In case of a 16-bit external memory width, the FMC will internally use HADDR[25:1] to generate the

address for external memory FMC_A[24:0]. In case of a 32-bit memory width, the FMC will internally use

HADDR[25:2] to generate the external address"

So my questions are:

Can A25 address line be used to switch command/data in case of 16 bit width? If yes how I can switch its state?

7 REPLIES 7

You could use any of the external address bits.

You'd read/write to a different address, ie 0x60000000 or 0x60000000 + (1 << 25)

1 << 26 -> 0x40000000 which would be another bank select.

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Yuora
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Thank you for answer.

it seems that when I use address 0x60000000 + (1 << 25) to read or write 16 bit width data it doesn't affect A25 pin but A24 pin is changed. It works like datasheet describes: "In case of a 16-bit external memory width, the FMC will internally use HADDR[25:1] to generate the

address for external memory FMC_A[24:0]". But stm32cubemx app allows select A25 pin to use for data/command switching in case of 16 bit width.

Is there any another way to set value to A25 pin? Or is it a bug in stm32cubemx application?

Haven't we already established that A25 Internally is shifted to A24 Externally for a 16-bit width device.

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Yes you're right, you can't use the A25 pin in 16-bit mode.

@Amel NASRI​  , this appears to be a bug in CubeMX.

JW

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OK, this problem is tracked internally.

Thanks for highlighting it.

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Thanks, Amel.

Jan

Presumably A1 thru A24 would function equally well, and A25 (FMC_A24 in 16-bit) if you aren't bound to CubeMX

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