I'm trying to build a transmitter based on the following concept:
An Arduino mega 2560 is used as a web server (so there's an Ethernet shield on top of it as well) allowing the user to choose the desired transmitter frequency through a website. According to the users selection, the Arduino needs to send 24 bits to a DAC (Digital to Analog Converter) which will then output the corresponding voltage. What happens later on with that voltage isn't important. The DAC used is the dac8551.
It has 3 important pins and their description according to the datasheet is: Din: Serial data input. Data is clocked into a 24-bit input shift register on each falling edge of the serial clock input. Schmitt-trigger logic input. SCLK: Serial clock input. Data can be transferred at rates up to 30 MHz. Schmitt-trigger logic input. /SYNC: Level-triggered control input (active-low). This is the frame synchronization signal for the input data. SYNC going low enables the input shift register, and data is transferred in on the falling edges of the following clocks. The DAC is updated following the 24th clock (unless SYNC is taken high before this edge, in which case the rising edge of SYNC acts as an interrupt, and the write sequence is ignored by the device). Schmitt-trigger logic input.
I have 2 questions: Question 1: Can I generate a clock signal for the SCLK pin of the DAC using the Arduino? Question 2: Which do you think would be the easiest way to send the Data to the DAC?
fikos:
I have 2 questions: Question 1: Can I generate a clock signal for the SCLK pin of the DAC using the Arduino?
I would assume there is a library for the DAC you are using that takes care of the clock signal.
fikos: Question 2: Which do you think would be the easiest way to send the Data to the DAC?
The library would also take care of this. Just call the appropriate function from the DAC library and it will convert your data to what ever form is needed by the physical DAC chip.
Well yea there is a library indeed. It uses the SPI interface. But would it be fine to use it while there's the Ethernet shield connected on the SPI interface as well? I guess I will have to check the library to make sure its not using the same pin for Slave Select (SS) as the ethernet shield. Where should I connect the SS pin (whichever it is) on the DAC though?
Why not set the SS high on the DAC while communicating with the Ethernet shield, and setting the SS high on the Ethernet while communicating with the DAC? Be sure to ensure your SD card SS (also called CS) is set high likewise if you use that function since it uses SPI also.
rjj100:
Why not set the SS high on the DAC while communicating with the Ethernet shield, and setting the SS high on the Ethernet while communicating with the DAC? Be sure to ensure your SD card SS (also called CS) is set high likewise if you use that function since it uses SPI also.
For the DAC the SS would be the /SYNC pin? Because there isn't a pin called SS.