UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Participant sjg69
Participant
6,544 Views
Registered: ‎03-29-2012

Marking an unconnected PS pin as input

Jump to solution

So I have a microzed board with the io carrier board. I designed a peripheral board to plug into the PS PMOD as well as 5 other PMODs along one side. All well and good. The problem is that I connected the PS SDA and SCL the wrong way around [sigh, board orientation ...] and they're wired through to an 8-way I2C mux chip using PMIO_14_500 and PMIO_15_500.

 

All is not lost, I brought out the pins on the PS PMOD to a pin header, and I also put a pin header on the peripheral board for SDA and SCL to the I2C mux chip, so I can map I2C0 to use PMIO_10_500 and PMIO_11_500 instead, and use jumper wires to connect those pins on the port pin-header to the I2C pin-header..

 

It still doesn't work, and I'm away visiting parents for 3 weeks over xmas so I can't easily do any rework. It occurred to me that the original pins I had connected the I2C mux to (PMIO_14_500 and PMIO_15_500) on the PCB may be interfering with the SDA/SCL signals via the jumper wires, so I'd like some way of marking pins PMIO_14_500 and PMIO_15_500 as inputs, which presumably makes them high-Z and would prevent any interference.

 

In the configuration panel for the Zynq processing system in Vivado 2015.4, I can *see* the port settings are 'inout' for PMIO_14_500 and PMIO_15_500, but I don't seem to be able to change them. Neither is it obvious to me that I can create an input port in the block diagram and connect that port to the fixed_io pin corresponding to my gpio pins (14 and 15). Perhaps there's a way to do it using constraints, but if so, its eluding me. 

 

As i said, I'm current sans-tools. I brought a logic analyzer with me, but I don't have a spare USB port to plug it into, a new hub arrives later today, at which point I'll be able to tell if the I2C signals are making it off the Zynq (and therefore the issue *is* with my board), but in the meantime I thought I'd also check to see if there's any possibility of "fixing it" in software/firmware...

 

Thanks for any help

 

Simon

0 Kudos
1 Solution

Accepted Solutions
Highlighted
Participant sjg69
Participant
12,721 Views
Registered: ‎03-29-2012

Re: Marking an unconnected PS pin as input

Jump to solution

So, replying to myself, but though it was worth updating...

 

The unused pins are (by default) mapped to the GPIO handler at the bottom of the MIO configuration. You can use the GPIO handler to set directionality and value... I still can't send I2C traffic, but hopefully the arrival of the USB hub today will let me figure out why...

 

Simon

0 Kudos
3 Replies
Highlighted
Participant sjg69
Participant
12,722 Views
Registered: ‎03-29-2012

Re: Marking an unconnected PS pin as input

Jump to solution

So, replying to myself, but though it was worth updating...

 

The unused pins are (by default) mapped to the GPIO handler at the bottom of the MIO configuration. You can use the GPIO handler to set directionality and value... I still can't send I2C traffic, but hopefully the arrival of the USB hub today will let me figure out why...

 

Simon

0 Kudos
Scholar trenz-al
Scholar
6,523 Views
Registered: ‎11-09-2013

Re: Marking an unconnected PS pin as input

Jump to solution

have fun, but tbh i am failing to see connection between usb hub and i2c-gpio issues..

0 Kudos
Participant sjg69
Participant
6,494 Views
Registered: ‎03-29-2012

Re: Marking an unconnected PS pin as input

Jump to solution

@trenz-al wrote:

have fun, but tbh i am failing to see connection between usb hub and i2c-gpio issues..


So, as I mentioned before, I'm vacationing at my parents house for xmas, so my tools collection is ... limited. My "workstation" consists of a Macbook Pro running Parallels/RHEL7... This means I have precisely 2 USB ports available. The first is used up by the JTAG programmer, the second by an external mouse. I would have thought the mouse was not necessary, but unfortunately Vivado under Parallels doesn't recognise a control-click using the mouse-pad as a right-mouse-click, so no context menus for me unless the mouse is plugged in...

 

When the hub arrived, I could plug in the mouse, a UART debug console, the JTAG programmer, and (importantly) the Saleae logic analyser. I2C now works :)

 

0 Kudos