DAC7760: I want A start model for the DAC7760 of the programming by spI

Hello,

I am a bit confused concerning what you are actually requesting. Is this a request for sample code? We do not have anythign specific to STM microcontrollers. If you can provide some inputs concerning how you would like to use the device I can give inputs about how to configure the registers, but support for the STM peripherals will need to come from that team.

Hello Kevin,

     So nice for your quick reply.

     Yes, I mean the sample codes. We use the daisy chain to control four DAC7760.

     The code with msp or other MCU is ok. What we mostly concerning is the demo for SPI.

Best Regards!

Beyond.

Hello Duke,

So nice for you.

And our daisy chain communication is ok now. 

I can do the read or write action to the 4 DAC7750. Yes, it is DAC7750. I make it wrong before.

Now I have a question with the DAC-output.

My config step:

step 1. Setup the control register to 0x55300D when the device booted up.// REXT-PIN, OUTEN, DCEN, RANG:4~20mA;

step 2: Set DAC Register: 0x010000, I found the current output is 19.8mA.

step 3: Set DAC Register: 0x014000, I found the current output is still 19.8mA.

step 4: set OUTEN bit to zero. The current change to be zero mA.

The clear pin is Low all the time.  The status register readout is 0x0004. 

I don't know why.

Our test method: 

Our Schematic part:

Best regards!

Beyond

Johnan,

Do the voltage output ranges respond as expected? Though it does appear that you are able to effectively communicate with the device, this would be a nice and simple method to concretely validate that.

0x0004 in the status register indicates a open-circuit or compliance voltage alarm on IOUT. Did you make any writes to the configuration register? If the APD bit is set then the IOUT is effectively being loaded by a very high-impedance through R95 in your design. I'm not sure why R95 has been included. Maybe a simple test for you would just be to remove R95 without any changes to the firmware.

The only other test I can suggest at this point to get more clues as to what could be the root cause is to switch to the internal current setting resistor to check if there is potentially any solder issue with the external resistor.