Digital to Analog (DAC) channels of Spartan 3e

[binali]

In Verilog, how to select two DAC channels of Spartan 3e for the output. I have attached, what I have in form of v code.

[drjohnsmith]

A spartan 3 has no DACs on the chip,
so i guess these are on the evaluation board ?
what's the evaluation board ?

[binali]

here is the DAC I am playing with

[drjohnsmith]

so you have some sort of evaluation board,
which has some sort of spartan chip on it,
and a LT2624 dac,

so you need to look at the documentation for your board to see how the dac is connected,

Or are you just asking how to select between two signals inside the fpga in Verilog ?

https://www.chipverify.com/verilog/verilog-4to1-mux

[binali]

Yes. Thanks for your reply. But My DAC channels are not MUX type (see fig:untitled2), therefore I can send digital data on them simultaneously but didn't know how to use them simultaneously. So far, I am successful at sending data to one channel by using protocol given below (see fig:untitled3).

[drjohnsmith]

As I understand it,
what your asking is about the LTC2624 , and how to use it.

I'd suggest that you are going to get good support from the manufacturer of that chip on their web site.

https://www.analog.com/en/products/ltc2624.html

[bruce_karaffa]

Looking at the DAC data sheet, you could write to each input register separately, then send the command to update all DACs.

[binali]

may be it is working as MUX, as it allows only one output register to attach to the respective terminal of DAC in the UCF file

[drjohnsmith]

How many DAC chips do you have ?

We think only one,
The dac chip has multiple DACs in it,
all on the same SPI bus, you only have the 4 SPI signals,

Inside the DAC, there are multiple registers,
at different address's
you use the SPI protocol to select which register you want to address.

To reinforce, the same pins are used for all the transfers.

Read the data sheet for teh DAC chip,
you will see al the registers in there, and how to address them to get the response you want.

[binali]

Ys, there are 4 dac, also we can access each dac by using SPI protocol as mentioned, but at the end you have to assign signal to SPI_MOSI which is connected on FPGA pin T4, therefore can only assign one out of four registers at SPI_MOSI, then at pin T4....?

[bruce_karaffa · Accepted solution]

Write to Input Register A (command = 0000) address = 0000 with one value.  Write to input register B with the other value.  Send the command to update all DACS command = 0001, address = 1111.