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DAC8563: DAC8563 on different MCU

MARIO MAINO
Prodigy 70 points
Part Number: DAC8563
Other Parts Discussed in Thread: ADS1263

Hello!

I tested my DAC8563 with an STM32F466RE and it works great, so I migrate on an STM32F767Zi and it doesn't work!

The two programs are quite the same, with only differences in SPI config.

To investigate the problem, I connected a logic analyzer and those are the two graphs:

This is the F4 (that works):

And this is the F7 (not working):

The two signals last about 10-15 ms, while the SYNC low signal on F7 is about 22ms (on F4:41ms).

 The initialization code is the same for the two micros.

What is happening?

Thanks and best regards

  • 0
    TI__Guru* 93735 points

    Mario,

    Can you check your SPI Mode? I believe that for this device, the SPI should be mode 1. In this mode, the clock dwells low (which you have), and the data is clocked in on the falling edge. In your logic analyzer plots, it looks like your data is being clocked in on the rising edge of SCLK, which would be mode 0. 

    If the SPI mode is incorrect, then the device may not receive the correct write command to program the DAC.

    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 70 points

    Thank you Joseph for your answer. On the F4 and the F7, the clock polarity must be set LOW and it works... after some test, I noticed that the overcurrent led on the F7 sometimes glow up: I powered the DAC8563 with an external supply and it now works! Surely the total current from the board was not sufficient to supply all the peripheral (DAC8563, ADS1263, two loadcell, OLED display, Modbus module... well, it's quite reasonable! )
    Thanks all and have a nice day!