Summary

The following code does not work with NUCLEO-H563ZI.

import math
from array import array
from pyb import DAC

# create a buffer containing a sine-wave, using half-word samples
buf = array('H', 2048 + int(2047 * math.sin(2 * math.pi * i / 128)) for i in range(128))

# output the sine-wave at 400Hz
dac = DAC(2, bits=12)
dac.write_timed(buf, 400 * len(buf), mode=DAC.CIRCULAR)

For STM32H5, DMA parameter should set:

• Actual DMA source datawidth to CTR1.
• The length is the amount of data to be transferred from source to destiniation in bytes. to use 12bit DAC.

Also, this PR modifies the definition of DMA_CIRCULAR for STM32H5 to prevent conflict with data width specification.

Testing

Tested code above with NUCLEO-H563ZI.
Also, DAC with 8bit still works after applying this PR.

Trade-offs and Alternatives

The value of DAC_CIRCULAR is changed:
from

>>> hex(DAC.CIRTUCLAR)
'0x1'

to

>>> hex(DAC.CIRCULAR)
'0x20000000'

Indeed, it won't be a problem because users do not need to be aware of value of DAC.CIRCULAR in most cases.