EXT DMA REQ How To ..

[craig239955_st]

Posted on December 21, 2006 at 09:32

EXT DMA REQ How To ..

[craig239955_st]

Posted on May 17, 2011 at 09:34

I want to connect a CCD B/W camera to a STR912 device. The camera clocks its 8 bit data out at a rate of 10MHz. I want to use External DMA request but I cannot find any information about how to use this.

Can someone give me a starting point ? Thanks Luc

[kais]

Posted on May 17, 2011 at 09:34

Hi Robosoft,

It's a littele bit unclear can you explain more your requirement:which kind of transfer you want to accomplish? Regards Eris.

[craig239955_st]

Posted on May 17, 2011 at 09:34

The CCD camera I use is the LM9360 (national semicondictor).

It consists of 100 horizontal rows, each with 128 pixels. After a snapshot has been taken, each pixel is converted into a 8-bit value. All the 12800 values are shifted out at the rate of a 10MHz clock. What I want to do is connect the 8 datalines to a GPIO port. At each positive transition, the actual value at the GPIO has to be stored in memory. After 12800 clockcycles, the memory is filled with all the 8bit values. At this moment, I use a system with a dual port memory. Adresslines of one side of the memory are connected to a hardware counter. Data lines from the memory are connected to the 8-bit port of the CCD. Each positive transistion of the clock, the data is latched into the memory, at the negative transistion, the addresscounter is incremented by one. After 12800 clockcycles the dual port eory is filled and the processor at the other side of the dual port memory can readout all the values. I wonder if it is possible to fill directly the STR912 memory using dma? I hope it this is clear (English is not my native language, as you can see...) Luc.

[craig239955_st]

Posted on May 17, 2011 at 09:34

;) Thank you very much.

Luc

[kais]

Posted on May 17, 2011 at 09:34

Hi,

Here attached an external DMA example aims to toggling leds on GPIO9 (STR9eval bord). DMA is configured to transfer data from memory “Src_Buffe�r to GPIO9 (data register). Note that the burst size is (1byte), after each one byte transfer the DMA need to be triggered, so that timer1 is configured to do this task. You can modify it to make a transfer from GPIO (data register) to memory. Hopefully this can help you. Regards.