adc0804 interfacing with fpga

[Maxima8]

Hi guys.

I am beginner in fpga. So i need help for my project. I have used 16 adc0804 in my project. The input for adc is from my 16 receiver curcuit. And now I want to interface the adc with FPGA. But i am very confusing. From my understanding, the output from adc0804 is digital. So, i just need to connect the output at DBn to gpio of de2 board. Is it correct guys? kindly help me please:---(

 

[shaiko]

If this is your ADC:
https://www.ti.com/lit/ds/symlink/adc0804-n.pdf
Then it utilizes a parallel bus.
You'll have to connect ALL the required signals to your FPGA and implement the logic.

 

[Maxima8]

Hi shaiko.

Thanks for your reply. Yes. it is my adc that i have used. So, do you mean that i just connect the DBn, intr, cs,wr, rd to GPIO of FPGA? Then i need to control cs,wr,rd signal? Could you explain little bit more detail. I still confuse.

 

[shaiko]

DBn, intr, cs,wr, rd to GPIO of FPGA

Yes,
Together with the data pins. That's quite a bit of wires...

Afterwards, you'll have to implement the control logic according to the waveforms in page 7.

 

[FvM]

The solution is not completely obvious, there are different options:

- Implementing a common data bus for all ADCs, sequentially accessing the data
Advantage: less FPGA pins
Disadvantage: more complex logic

- Individual data lines for each ADC
Advantage: Simple logic, fast access without sequences. Some ADC pins can be connected to fixed level, at least nCS.
Disadvantage: many FPGA pins needed

 

[ravindragudi]

First you need to think on how you can reduce the number of ADCs from 16 to some convenient number say 4 or 5. Then it will be easier for you to think of interfacing ADCs to the fpga.

if you use a 'n' channel diff mux, things will be much simpler. Refer to the attached figure taken from the DS. This should help you. Later try using a configuration similar to Fig 61 - Interfacing Multiple A/Ds in an MC6800 System.

 

[Maxima8]

Yes,
Together with the data pins. That's quite a bit of wires...

Afterwards, you'll have to implement the control logic according to the waveforms in page 7.

Hi shaiko.

Thanks for your reply. I am very very beginner in vhdl. I have write some code for the adc and i know its wrong. But could you give me some ideas how to build the vhdl

 

[shaiko]

1. Your code won't compile due to syntax issues.
2. Even if it would compile - it won't synthesize. You can't use "after" to describe real logic.

I suggest you acquire minimal VHDL skills before you continue
Please watch this video:

**broken link removed**