SPI write read is not done properly

[MDeva.1]

Hello,

I am working on STM32h7 controller. I configure the AD9106 DAC to SPI. When I tried to write read the configuration register some some registers are get read write and some not why these happening I check the register they are read write able also I changes the SPI frequency low to hgh. For DAC external clock is 150MHZ and SCLK is 4MHZ.

[Bubbles]

Hi @MDeva.1​,

what makes you think there's a problem with STM32H7?

Try analyzing the communication using a logic analyzer or some SPI sniffing device such as Beagle.

BR,

J

[MDeva.1]

I check on PICOSCOPE. But when I tries to read that particular registers I get the value 0 .

I tried to make the RUN bit 1,but when I read back I get the zero.Why these happening.Here is my code.

Can you me help me.

[S.Ma]

The state machine has multiple spi connection configuration. Check which one is enabled by default. If it is 3 wires, this is not the native 4 wire mode and requires that you disable STM32 Mosi pin when starting to read, then revert back manually when going back to output mode. If your SCK toggles, I guess the gpio config is ok.

[MDeva.1]

Hi,

Can you please elaborate the things means what thinks I need to do ?There are two DACs are connected to the SPI4. MOSI ,MISO ,CLOCK are same. Right now I just try to access the DAC1 and for these I make the CS pin HIGH of the DAC2 through out the execution..

In these picture of waveforms I tried to write and read back the address of 1E RUN bit.

Write address=0x001E

Read address=0x801E

Value=0x0001;

I attaché the schematic Please have look.

Can you please help me .

[S.Ma]

2 slave dac on the same bus commandd 4 wire spi. Not multi drop, here it is daisy chain. STM32.MOSI goes to DAC1.SDI, DAC1.SDO goes to DAC2.SDI, DAC2.SDO goes to STM32.MISO

As it is daisy chain, you have 2 dac to update in one shot, so the data packet should be longer.... hope this helps.

[MDeva.1]

We does not use the Daisy chain. We give parallel signal to DAC1 and DAC2 , using the chip select establish the communication for DAC1 or DAC2. At time we are not communicate to DAC1 and DAC2. Right now I just try to communicate with DAC1, for these I make CS pin of DAC2 High

[S.Ma]

I think an ST example with spi adc and dac would help many users...