ColdFire/68K Microcontrollers and ProcessorsのトピックRe: DMA transfer with MCF52233

DMA transfer with MCF52233

antonioSA — Thu, 03 Apr 2008 03:47:36 GMT

Hi everyone

I am making a project with the MCF52233, because of a speed constraint I need to use DMA transfer.

I Have a FIFO memory and a MCF52233; so I am qoing to send data from FIFO to mcf52233.

I am a little confused about how DMA works with external devices

In order to get the right data at right time in the MCF52233 GPIO port I need to send a clock signal to the FIFO memory.

How can I produce that clock signal ? using DTOUTn pin?

How can I sure that the DMA clock is synchonized with the external FIFO memory.

Thanks for Your help

Antonio

Re: DMA transfer with MCF52233

ShenLi — Sat, 12 Apr 2008 14:57:50 GMT

Antonio,I am doubting how you connect the external FIFO with MCF52233? We do not have flexbus for MCF52233.

Re: DMA transfer with MCF52233

antonioSA — Wed, 16 Apr 2008 02:50:19 GMT

Hello Shen,

The FIFO memory have two read control signals and one read clock. I am traying to control that signals with the coldfire. My first option was to connect the FIFO as a pheriperal device (using GPIO). I generated the read clock with an GPIO output pin. The result was a FIFO output bandwith of 1.4 Mbytes/sec. The problem is that I need to get FIFO data at least 5.2Mbytes/sec, that is the FIFO input bandwith. My second option is to use DMA, but I am not pretty sure how it works...

Thanks

Antonio

Re: DMA transfer with MCF52233

ShenLi — Sun, 20 Apr 2008 08:58:31 GMT

That's right. You cannot use the DMA for the external FIFO. As for MCF52233, the DMA can only transfer data from and to system memory map address. As MCF52233 does not have the Flexbus or async external bus, we can not map external device to system memory map.

ShenLi