cancel
Showing results for 
Search instead for 
Did you mean: 

USB Superspeed Peripherals

Cromagnon
New Contributor II

Hi,

I have build up the application and the video is displayed correctly on the PC.

My configuration is 8 bit video data (grayscale) using an 8 bit data bus at the GPIF-II interface. The coding is YUV2, which means that for every pixel sent, I transfer with the first 8-bit a video byte (0xNN) which is followed by a second transfer with the value 0x80. This works well !

Now I want to improve the performance and want to configure the GPIF-II interface to use 16 bit for the transfer. Every pixel is  transferred as a 16 bit word with 0x80 in the upper byte and the video data (0xNN) in the lower byte. This should result in a data sequence according the Intel little endian mode. 

I have only changed the data bus width in GPIF-II to 16 bit. My expectation was that now the DMA buffer will filled up with a sequence of data like: 0xNN, 0x80, 0xNN, 0x80, ... The amount of transferred data is the same therefore I did not change any there parameter.

The screen shows only black and there is no error message in the debug console. I have also tried to switch the byte order but this did not help.

It seems for me that something is missing in the configuration or the supplied software.

Q: What do I have to change, that the 16 bit version will work like the 8 bit version before?

 

Kind Regards

Cromagnon

0 Likes
1 Solution
Hemanth
Moderator
Moderator

Hi Cromagnon,

Please confirm if you have configured LD_ADDR_COUNT and LD_DATA_COUNT(counters used in GPIF state machine) accordingly, when you increased the GPIF bus width.

Please refer to section 3.5 of AN75779

Regards,

Hemanth

View solution in original post

0 Likes
2 Replies
Hemanth
Moderator
Moderator

Hi Cromagnon,

Please confirm if you have configured LD_ADDR_COUNT and LD_DATA_COUNT(counters used in GPIF state machine) accordingly, when you increased the GPIF bus width.

Please refer to section 3.5 of AN75779

Regards,

Hemanth

View solution in original post

0 Likes
Cromagnon
New Contributor II

Hi Hemanth,

thx for your hint. I remembered the setting of this two parameters and also found the way to change them.

Now it works with 16 bit transfers.

Kind Regards

 

0 Likes