I have a problem about the sgdma when I used it to transfer vga data(800x600x4bytes)!

--- Quote Start ---

Are You sure You're not filling the invisible data of the display? Is it tft matrix only? Also do You use write until EOP or a fixed length?

Did You allocate enough memory for data pointer? Descriptor memory takes 32 bytes long data in the memory. If You're allocating descriptor memory with malloc(), then it is placed in heap, which I suppose is in the SDRAM? However I don't know if it would actually work that way.

--- Quote End ---

1.The data is right,I assured.

2.tft monitor.

3.I use the fixed length(1920000bytes).The number of descriptors is 30. each with 65532 bytes to transfer. The last one is 19572bytes.

4.I use the enternal SDRAM as the data memory.The data pointer declared as

alt_u32 *buffer = (alt_u32 *)SDRAM_VGA_DATA_BASE;

thank you!