AN75779 (FX3): changing little-endian to big-endian

[AKS]

Hello. How can I change the byte order from little endian (default in AN75779) to big-endian.

what/where should I change in uvc and descriptor file to support it for big-endian order.

Please suggest~

Thanks.

Regards.

[Biren_R]

Hello,

Is your data bus from the image sensor is more than 8 bits?

Best Regards,
Biren

[AKS]

@Biren_R Hello.
No, Its 8-bit but the data is 16-bit multiplexed on 8-bit bus.

Regards.

[Biren_R]

Hello,

I am not getting how you multiplex 16-bit over 8-bit can you explain it or send GPIF configuration?

Best Regards,
Biren

[AKS]

@Biren_R Hello.

This is similar to the AM75779 mentioned the camera sensor interface where the bus is of 8-bit and pixel data from sensor is 2 byte (16-bit) and receiving over 8-bit bus multiplexer. So, the one data line (ex. D0) receiving 2 byte data as 1byte - 1byte order.

Hope you understand! 

Regards.

[Biren_R]

Hello,

In this case, FX3 can't reorder data with GPIF configuration so i suggest you can reorder this before FX3 or you can reorder at the application side in the host.

Best Regards,
Biren

[AKS]

@Biren_R Hello.

then what is the role of selecting big-endian/little-endian at GPIF configuration?

[Biren_R]

Hello,

It is useful when you have more than an 8-bit data bus, in your case data bus is 8-bit only.

Best Regards,
Biren

[AKS]

@Biren_R Hello.

So it means that the data order can not be managed by FX3 GPIF designer, Is it so?

[Biren_R · Accepted solution]

yes, we can't manage data orders using GPIF if it is just an 8-bit data bus, we can change the endianness if we have more than 8-bit data.

Best Regards,
Biren

[AKS]

@Biren_R Hello.

Thanks for your comment. I confused, you said "we can change the endianness we have more than 16-bit data.",  or it should be more than 8bit? 

Please clear.

Thanks.

[Biren_R]

Sorry, It is a mistake more than 8-Bit data is currect. 

Best Regards,
Biren

[AKS]

@Biren_R Thank you for clearing this.

means, the FX3 endianness is depends on the 'bit-bus' if its more than '8bit data bus', doesn't matter how the data (data order) is coming on the bus.

Thanks,

Regards.

[Biren_R]

Hello,

endianness itself applies only when data is more than 8 bits, in your case you have 16-bit but it receives as 2 8-bit data. if data bus more than 8-bit then you can select endianness from the GPIF tool.

Best Regards,
Biren