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STM32H7 ADC 8-bit dual mode with DAMDF=0b11 is ambiguous in reference manual RM0433

Piers
Associate II

on page 997 of RM0433 Rev 7 it first says 2 bytes are transferred each DMA request, and then that 4 bytes are transferred each DMA request:

DAMDF=0b11: This mode is similar to the DAMDF=0b10. The only differences are that

on each DMA request (two data items are available), two bytes representing two ADC

converted data items are transferred as a half-word.

This mode is used in interleaved and regular simultaneous mode when the result is 8-

bit. A new DMA request is issued when 4 new 8-bit values are available.

The given example also says 4 bytes.

When testing the first statement seems to be true: the DMA request is issued after 2 new 8-bit values are available in last half-word of the CDR register.

On page 1046 it confirms this:

In MDMA=0b11 mode, bits 15:8 contains SLV_ADC_DR[7:0], bits 7:0 contains

MST_ADC_DR[7:0].

Only MDMA must be changed to DAMDF in this sentence.

Furthermore the following statements contradict each other:

page 997:

When DAMDF mode is selected (0b10 or 0b11), bit DMNGT[1:0]=0b10 in the master ADC’s

ADCx_CCR register must also be configured to select between DMA one shot mode and

circular mode

page 1020: about DMNGT register

In dual-ADC modes, this bit is not relevant and replaced by control bit DAMDF of the

ADCx_CCR register.

It seems the note on page 1020 is incorrect, and should be deleted.

Please check and update RM0433. Thanks!

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