Operating AD5780 EVAL Board Via MicroController

Question

OK, so thanks in advance because I am new here. I am reading the AD57XX drivers here https://wiki.analog.com/resources/tools-software/uc-drivers/renesas/ad5780 and am struggling to understand how to get the device working and understanding it properly.

I am using code here https://github.com/maxgerhardt/arduino-ad57xx-driver/blob/master/src/main.cpp in order to test the DAC. I have several questions about the drivers and operation in general. I will itemize them if that is ok

1. Where in the drivers am I performing Slave Select and where am I determining Clock Speed? I have looked through the C in the drivers library, and it seems that each command, whether reading or writing selects the Slave/Master each time? I see no reference to which pins on my microcontroller it is reference though so I do not know if any of this is right.
2. Why do I need to be reading in the Control Register or anything from the DAC at all? Why does this matter? All I want is to output a voltage
3. How do I perform the right conversion to a voltage that I want? The command " AD57XX_SetDacValue() " takes a long, but I do not understand how that relates to a float value of voltage. Say I want 2.35 Volts, or a Sine Function from -2 to 2 Volts, how do I do this conversion?
4. I don't know how to debug the system in general. When I run the example code, which is supposed to output a triangle wave function, I get a sin function, which seems to just be noise.

Answer 1

Where in the drivers am I performing Slave Select and where am I determining Clock Speed? I have looked through the C in the drivers library, and it seems that each command, whether reading or writing selects the Slave/Master each time? I see no reference to which pins on my microcontroller it is reference though so I do not know if any of this is right.

The slave select is controlled within the SPI_Write() function. It uses the PinMgt_PinWrite() function to do the slave select control, which in turn selects a pin from the pinMapping[] lookup table.

The clock speed is set in AD5780_Init().

Why do I need to be reading in the Control Register or anything from the DAC at all? Why does this matter? All I want is to output a voltage

You don't. The code is just for demonstration purposes. It shows you how you could query those registers. If you don't need to, then don't.

How do I perform the right conversion to a voltage that I want? The command " AD57XX_SetDacValue() " takes a long, but I do not understand how that relates to a float value of voltage. Say I want 2.35 Volts, or a Sine Function from -2 to 2 Volts, how do I do this conversion?

That value is the raw value to set the DAC to. You refer to the DAC datasheet to know what that value equates to. In this case the range is from \$V_{REFN}\$ to \$V_{REFP}\$. Divide that range by 2¹⁸ and you have the voltage per bit.

I don't know how to debug the system in general. When I run the example code, which is supposed to output a triangle wave function, I get a sin function, which seems to just be noise.

You need some debugging tools. Things like a logic analyser to be able to acually see what the IO pins of your MCU are doing. An oscilloscope can be used to see if a signal is present, but to see all the SPI signals together you really want a logic analyser.