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Hi, I am currently using IN EP3 of the LPC1769 to realize Isochronous transactions to the Host. I have configured the this endpoint in the DMA mode
LPC_USB->EpDMAEn = 0x80;
I enable the DMA on the EP when I receive the Set Interface command from the Host. However, I see that the EpDMAEn does not change its value to 0x80 as desired (this could probably be because the register is Write Only, but I am not sure). Please can someone let me know the conditions under which the DMA mode for the EP would get disabled?
In order to get around this problem I write to the above register everytime I create a DMA Descriptor. Is this a good method? Many time we end up loosing bytes of information on the host but I am not sure if it is actually because of this.
Any help in this regard would be much appreciated.
Thanks very much.
Regards, Shaunak
Hi Tsuneo,
I had another question regarding the LPC1769 DMA mode.
If the two EP buffers of the isochronous EP have been filled due to 2 DMA bursts and the host now starts to read the data from the 1st buffer. If a DMA burst is initiated at this moment, will the data being transmitted to the Host be corrupted or replaced?