Error in the reference manual?

[dgiovanelli]

Hello,

I would like to signal a possible error on the reference manual of the STM32L496 (RM0351 Rev 6)

At pag 348, section 11.4.5, Table 45 the first line (source port 8bit, destination port 8bit) indicates that the Number of data items to transfer is 8, however I think it should be 4.

Moreover: I don't clearly understand the description of the NDT register. It is described as "the number of data items to transfer", however it looks more like as "the number of DMA transfer". In fact, regardless the sizes of data (MSIZE, PSIZE) the NDT is decremented after every DMA transfer, being it 32,16 or 8 bit. Then for me the fact that it refers to the number of data items is misleading.

[waclawek.jan]

In the single-port DMA NDTR indeed indicates plainly number of transfers, as there's no data packing/unpacking and the number of memory-side transfers equals to number of peripheral-side transfers.

The dual-port DMA ('F4, 'F7) is different and there NDTR determines the number of peripheral-side transfers. The related RMs don't say this out clearly either...

JW

[dgiovanelli]

Thank you, actually when I'm coding for the L4 I read the L4 RM and I don't care about F4. However, I perfectly understand that is really valuable to have the same terminology for both series even if the hardware is slightly different, and also I haven't read really all the ST documentation and I might have missed something.

Said this, the main reason for the post was to indicate the possible error in the table, now I see you have notified an ST Employee so thank you.

[waclawek.jan]

> (RM0351 Rev 6)

> At page 348, section 11.4.5, Table 45 the first line (source port 8bit, destination port 8bit) indicates that the Number of data items to transfer is 8, however I think it should be 4.

Indeed.

@Imen DAHMEN​  , can you please have a look?

Thanks,

JW

[Imen.D]

Hello,

Thank you for bringing this to our attention.

We will correct this typo in the coming release of the RM0351.

Best Regards,

Imen

[waclawek.jan]

Thanks, Imen.

Jan