Pmod connect with Microblaze or ZYNQ?

Charlie_Meng · April 29, 2021, 6:43pm

Hi, Sir,

I want ask a question: if the PYNQ pmod module is based on Microblaze system, which mean I could not use ZYNQ system to connect Pmod IP, right? If I want use ZYNQ and python to control it, if I need write library about it by myself? Thank you!

schelleg · May 1, 2021, 9:30pm

Yes, you would need to write new code to control that PMOD device directly from the PS ARM processors. And then of course you would need to create the proper overlay to connect the PS directly to PMOD pins.

Charlie_Meng · May 3, 2021, 8:34am

Hi, Schelleg,

Thank you! By the way, do you know the PYNQ PMOD module is based
on PMOD DA1 or DA4? Thank you!

Best regards,

schelleg · May 3, 2021, 2:41pm

The PMOD DAC driver is written for the DA4.

github.com

Xilinx/PYNQ/blob/bedfd63ca9f15712e651b265a4954a2f817d325a/pynq/lib/pmod/pmod_dac/src/pmod_dac.c#L37


      
          *  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 
          *  OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
          *  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
          *
          *****************************************************************************/
          /******************************************************************************
          *
          *
          * @file pmod_dac.c
          *
          * IOP code (MicroBlaze) for Pmod DA4
          * Pmod DA4 is write only, and has SPI interface.
          * Switch configuration is done within this program, Pmod can be plugged 
          * into upper row or lower row of the connector.
          * The Pmod DA4 is an 8 channel 12-bit digital-to-analog converter run via 
          * the analog devices AD5628. 
          * http://store.digilentinc.com/pmodda4-eight-12-bit-d-a-outputs/
          *
          * <pre>
          * MODIFICATION HISTORY:
          *

Charlie_Meng · May 5, 2021, 11:08am

Hi, Schelleg,

I have bought Pmod DA4 and setup test system as PYNQ board recommeneded like following picture shown. But it doesn’t work (use PYNQ board base.bit and Pmod.DAC code, A pin has no response), Do you know why? Thank you!

I have seen the guide as below, Is this possible the internal clock problem? Thank you!

cathalmccabe · May 5, 2021, 7:32pm

No, the docs you link to should not be the problem.

How are you testing it?
There is an example notebook here, but it includes a loopback test with an ADC:
https://github.com/Xilinx/PYNQ/blob/master/boards/Pynq-Z1/base/notebooks/pmod/pmod_dac_adc.ipynb
You can refer to the DAC part of the code.

If you are still having problems, please post your code and which version of PYNQ are you using.

Cathal

schelleg · May 5, 2021, 10:50pm

I just tested PYNQ/pmod_dac_adc.ipynb at master · Xilinx/PYNQ · GitHub and operating as expected. Let us know your setup. I tested on a PYNQ-Z2 with a v2.6 image.

Charlie_Meng · May 6, 2021, 8:11am

Hi，Schelleg and Cathalmccabe,

Thank you! I have found the problem. My setup sequence has problem. After run the code: dac = Pmod_DAC(ol.PMODB), I connect the Pmod_DA4 hardware module. after that, run the code: dac.write(2). It has no response. The correct way is connect the pmod_da4 hardware at first, then run all the code. The reason is the code: dac = Pmod_DAC(ol.PMODB) will initial the DAC chip and define reference voltage.
But I have another problem, if I want to use all 8 channels DAC output, If I need modify the library as below link said: Digilent PmodDA4
Thank you!

Charlie_Meng · May 6, 2021, 8:12am

Hi，Schelleg and Cathalmccabe,

Thank you! I have found the problem. My setup sequence has problem. After run the code: dac = Pmod_DAC(ol.PMODB), I connect the Pmod_DA4 hardware module. after that, run the code: dac.write(2). It has no response. The correct way is connect the pmod_da4 hardware at first, then run all the code. The reason is the code: dac = Pmod_DAC(ol.PMODB) will initial the DAC chip and define reference voltage.
But I have another problem, if I want to use all 8 channels DAC output, If I need modify the library as below link said: Digilent PmodDA4
Thank you!

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Pmod connect with Microblaze or ZYNQ?

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