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hey ppl, i am encountering a little technical confusion with my work.m dealing vit dsp up(bf 533) ive written a code for dma[sdram] to ppi data transfer.my system clock has been configured for 126 mhz.my dma takes sclock/2 value which is around 63 mhz.ive configured my ppi to run at 63 mhz as per my application requirement.am encountering underrun error.when i run my ppi at a lower clk freq i dont encounter this error.but my sclock value max is 133mhz and my dma always takes only sclk/2 value. i very badly need a solution for this problem i need to eliminate this underrun error.how do i do that.......what do u think could be the plausible reasons for this error generation other than the already inferred fact that dma and ppi are running at the same freq. regards vaishali |
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Data transfer frm dma to ppi
Started by ●August 20, 2004
Reply by ●August 20, 20042004-08-20
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Hi Vaishali, We encountered similar problem with PPI to SDRAM. It seems that in some case PPI FIFO may fill up (or dry up) in your case before controller could gain access to required data in SDRAM. We solved it (more or less) by using 16 bit pack option which cut by half the stress on DMA controller. Of course this works only if you use 8 bit PPI. Other option was to stream data from L1 with another routine moving data from SDRAM to L1 with memory DMA. There may be something to do also by playing on DMA bus scheduling parameters but we didnt go that far. Regards Gilles Gautier > -----Original Message----- > From: Vaishali [mailto:] > Sent: vendredi 20 ao 2004 12:15 > To: > Subject: [adsp] Data transfer frm dma to ppi > > hey ppl, > > i am encountering a little technical confusion with my work.m dealing > vit dsp up(bf 533) ive written a code for dma[sdram] to ppi data > transfer.my system clock has been configured for 126 mhz.my dma takes > sclock/2 value which is around 63 mhz.ive configured my ppi to run at > 63 mhz as per my application requirement.am encountering underrun > error.when i run my ppi at a lower clk freq i dont encounter this > error.but my sclock value max is 133mhz and my dma always takes only > sclk/2 value. i very badly need a solution for this problem i need to > eliminate this underrun error.how do i do that.......what do u think > could be the plausible reasons for this error generation other than > the already inferred fact that dma and ppi are running at the same > freq. > > regards vaishali > > > _____________________________________ > Note: If you do a simple "reply" with your email client, only the author > of this message will receive your answer. You need to do a "reply all" if > you want your answer to be distributed to the entire group. > > _____________________________________ > About this discussion group: > > To Join: Send an email to > > To Post: Send an email to > > To Leave: Send an email to > > Archives: http://groups.yahoo.com/group/adsp > > Other Groups: http://www.dsprelated.com/groups.php3 > > Yahoo! Groups Links > > |
