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DMA Interrupts

Question asked by price.andrew on Aug 9, 2013
Latest reply on Aug 12, 2013 by price.andrew
Here's the situation - I'm transferring some data from I2S to a buffer in memory via DMA.  The DMA is set up to be double buffered - I'll skip all the initialization code but here are what the DMA registers look like just before I enable the stream:

LISR: 0x00000000
HISR: 0x00000000
LIFCR: 0x00000000
HIFCR: 0x00000000
CR: 0x00062D5E
NDTR: 0x00000200
PAR: 0x4000380C
M0AR: 0x20001A84
M1AR: 0x20001E84
FCR: 0x000000A0

The I2S is setup for 48kHz and I have 2 int16_t buffers of 512 samples each.  So, I would expect that I get an interrupt every 256/Fs = 5ms telling me a buffer has finished playing. Two questions:
1) Which interrupts should I be looking for (HT or TC or both)?
2) Regardless of the type I seem to only get interrupts every 10ms - any ideas why?  The weird part is that I also seem to get the HT and TC flags set on the same interrupt (instead of offset 5ms as I'd expect).