I am using an AD9234 ADC to capture data in the modes 2x500MS and 1x1000MS. I've seen that FMCDAQ2 uses a trigger signal on gpio_i with the signals trig_p and trig_n. This input is used to start captureing on the PS side is this correct?
I would like to add two trigger signal inputs to my AD9234 FPGA Board. For example when I want to capture data for 20uS I could apply this 20uS impulse. When the signal is High, the ADC captures the Data into the FIFO and the DDR. I could then read out the data from the DDR memory using DMA.
So here are my questions:
- How could I achive this kind of triggering? Is it possible to perform the triggering for each channel or is this only for both cannels possible?
- On DAQ2 the Trigger Input is only used to interrupt the PS and start capturing correct? This will losse samples right, as there is a latancy between trigger start in PS Software and the real applied data.
- How does the PS recognize a trigger event? should I use the interrupt inputs of the Zynq PS?
That trigger is not used by the software, it's simply connected to that GPIO intput and that's it.
Answering to your questions:
1) The current design of the axi_adcfifo does not support this kind of triggering. The data capture is started by the dma_xfer_req signal. I do not recommend to connect your trigger to the dma_xfer_req, simply because that signal indicates other events too, and will break the functionality of the core.
2) 3) is kind of irrelevant I guess, taking the fact that there isn't any software implementation for this trigger/GPIO.
But, this triggering mechanism is something that we are working on, and hopefully we will have an IP soon, which will support something like this.
thanks for your reply
Ok sounds good to me. As I am planning a custom data acquisition board where I want to use triggering, what should I provide to support this functionality ? Just like the DAQ2 board a simply GPIO pin of the FPGA?
Sorry Nils, I missed this thread.
You just need create the hardware infrastructure (in case of DAQ2 it's an SMA connector connected to PL); how will you use that external signal is really up to you. You can connect it to a GPIO or use it as a enable signal in your HDL design.
thanks for your feedback