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Visitor jose_rocha
Visitor
10,129 Views
Registered: ‎06-19-2008

problem with LTC2624 DAC (Spartan 3E starter Kit)

Hello:Please help solving the following problem with LTC2624DAC (Spartan 3E starter Kit)Problem:The LTC2624 Digital to Analog Converter (DAC) on S3e kit always outputs zero on SDO Line.  However the DAC receives the word data correctly, because its analog output has a fine voltage. I’m sending two (three, four) times, the same data word but the SDO signal is always zero.Dos anyone can help?  (Please note that the N10 FPGA pin  is shared with the ADC-LTC1047.  Is the LTC2624 SDO line a tri-state output?) Thank you very much.

jose rocha

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5 Replies
Historian
Historian
10,112 Views
Registered: ‎02-25-2008

Re: problem with LTC2624 DAC (Spartan 3E starter Kit)


jose_rocha wrote:
Hello:Please help solving the following problem with LTC2624DAC (Spartan 3E starter Kit)Problem:The LTC2624 Digital to Analog Converter (DAC) on S3e kit always outputs zero on SDO Line.  However the DAC receives the word data correctly, because its analog output has a fine voltage. I’m sending two (three, four) times, the same data word but the SDO signal is always zero.Dos anyone can help?  (Please note that the N10 FPGA pin  is shared with the ADC-LTC1047.  Is the LTC2624 SDO line a tri-state output?) Thank you very much.

jose rocha


From the LTC2624 data sheet: "The serial output of the shift register appears at the SDO pin. Data transferred to the device from the SDI input is delayed 32 SCK rising edges before being output at the next SCK falling edge."

 

So you need more clocks.

 

-a

----------------------------Yes, I do this for a living.
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Visitor jose_rocha
Visitor
10,095 Views
Registered: ‎06-19-2008

Re: problem with LTC2624 DAC (Spartan 3E starter Kit)

Dear bassman59 :Thanks for your replay, but it doesn’t work. I was aware of the 32 SPI clock cycles delay.  However any other suggestion is welcome. Best regardsJose Rocha
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Visitor shahradp
Visitor
8,396 Views
Registered: ‎04-04-2008

Re: problem with LTC2624 DAC (Spartan 3E starter Kit)

I think if you have correct voltage output based on digital input, then you have to see  signals on SDO after 32 Clk. I have the design that does it and can see SDO signal.
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Visitor iremy
Visitor
7,995 Views
Registered: ‎10-01-2008

Re: problem with LTC2624 DAC (Spartan 3E starter Kit)

I cannot see neither the analog output nor the SDO (they are always 0). I used the behavioral simulation to observe the output pins of the DAC. I use 1us delay between each transaction and the data flow seems correct.

Can you please heIp me?

I can send my code if you want.

Thanks in advance,

İrem 

 

 

 

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4,687 Views
Registered: ‎01-11-2012

Re: problem with LTC2624 DAC (Spartan 3E starter Kit)

i am trupesh vasoya and i am new in fpga..currently i working with dac on spartan 3e kit..but i don't have any output on any channel ..plz help me ...i am working in vhdl...so plz help me or send your code..thank you very much and wait for positive response....

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