JTAG-SMT4 Information

[AA_TO]

Hi,

I'm planning to use this module with a single UART port (along with JTAG). A couple of questions:

1. Is it OK to leave all unused UART port pins open? 

2. I do not need hardware flow control pins (RTS/CTS) on active UART port - OK to leave them open?

3. Can unused UART ports be disabled in software?

4. What is the approximate current consumption for the Vdd pin?

Thanks!

[JColvin]

Hi @AA_TO,

1. Yes, you may leave them open.
2. Yes, you may leave them unconnected.
3. I believe they are normally disabled by default, though all of the pins on each of the 3 UART ports have 100k Ohm pull-up resistors implemented so they will not be left floating.
4. We don't have an official spec for average current consumption, though another co-worker of mine measured an average 94 mA when running JTAG at 30 MHz and a single UART channel at 1 MBaud. When the USB controller was held in reset, the current consumption seemed to be about 25 mA.

Let me know if you have any questions.

Thanks,
JColvin

[AA_TO]

Thank you!

[AA_TO]

Hi, I have the module connected to a Windows 10 PC. Windows is reporting error with code 43. Module is powered by 3.3V LDO which uses USB_VBUS (5V) as an input. I installed the latest FTDI drivers (CDM212364), but it does not seem to work - Windows assigns the standard USB driver to device instead of the FTDI one. When manually changing driver, none of the available FTDI options seem to work.  Tried installing Adept - which in my understanding also installs the drivers, but still no success. Vivado (2020.1) also does not see the module.

Do you have any recommendations on how to handle software/driver issues of JTAG SMT4?  

[malexander]

@AA_TO

Can you provide the following:
1. A screenshot of the Windows error message.
2. A screenshot of the devices as they appear in device manager.
3. A snippet of the schematic that includes all connects to the JTAG SMT4.

Thanks,
Michael

[AA_TO]

Hello Michael,

Here are some screenshots:

 

As of schematic - I'm at prototyping stage now and don't have "official: schematic as of yet. I attached the module to my existing board for checking. USB+/- (pins 26/25) connected to the MicroUSB connector, grounds (9, 18, 27) to my board ground. I used 5V USB_VBUS with 3.3V LDO for VDD (pin 19); USB 5V is connected to VBUS_DETECT (pin 24). VREF_JTAG (pin 28) connected to on-board 3.3V power rail. JTAG pins (1..4) connected to 14-pin on-board JTAG connector (Xilinx standard). When I connect Xilinx JTAG pod to this connector it works fine. I'm going to change the module power from USB to just on-board 3.3V to avoid any power sequencing issues, but not sure if it is going to solve the wrong driver problem. One more thing - I have Linear Tech Power Play SW installed on my PC. It works with a USB to I2C Linear pod which apparently uses FT chip; I believe it has installed FTDI drivers (slightly older version). Not sure if this may cause any conflicts.

So far I don't have any serial bus connections (eventually will need just a single port. PS_POR_B and PS_SRST_B are disconnected as of now, but I will need them eventually.

 

 

Edited December 6, 2021 by AA_TO

[malexander]

@AA_TO

The screenshots you sent me don't indicate a driver problem, but rather what is likely a USB signal integrity issue. Have you tried using a different USB cable, or plugging it into a different port? What about a different Windows 10 PC? When you say you attached this to your existing board - is that a board that has SMT pads for the JTAG-SMT4 that follow the land pattern guidelines provided in the reference material? Have you added any additional series resistors or ESD diodes to USB D+/D-?

[AA_TO]

I've tried different PC/Cable with the same result. Signal integrity definitely can be an issue - USB signals are connected to the microUSB  connector with just two single wires, however short they are. There are no pads etc on the board - I kind of breadboarded the whole thing. I'm going to chop a good USB cable and solder wires to the module directly, hopefully it will work better. Thanks! 

[malexander]

@AA_TO

Breadboard's add a lot of capacitance so that's probably why it doesn't work. Hopefully, it will work with your cable solution, but this is not how the module was intended to be used.

[AA_TO]

Direct USB cable connection did the trick:

So windows is now happy - it sees 3 com ports and 4 USB serial  conv. - I guess JTAG being the other one. Vivado however did not find the Xilinx device, will have to do more troubleshooting.

[malexander]

@AA_TO

Which version of Vivado are you using? As I recall 2020.1 is the oldest release that supports the JTAG-SMT4.

Thanks,
Michael

[AA_TO]

I have 2020.1 version - should I upgrade?

[malexander]

@AA_TO

As far as I know 2020.1 should work but you could try upgrading to a newer version.

Have you checked to see if the Adept GUI application can see the JTAG_SMT4?

Thanks,
Michael

[AA_TO]

Adept shows it:

 

Next will update Vivado to the latest version.

[AA_TO]

Well, it actually works with my version now, don't know why it was not working yesterday - have not done anything to it.

 

Thanks for your help Michael! Happy Holidays!

[malexander]

@AA_TO

I'm glad you got it working Happy holidays!

[AA_TO]

Thank you!

Actually one more question - how can I issue PS_POR and PS_SRST commands? I don't think Vivado has that ability.

[malexander]

jtagpins.tcl

 

@AA_TO

It's my understanding that Vivado/Vitis/SDK drive PS_POR and PS_SRST automatically as needed. However, it is possible to drive them manually. It's been quite a long time since I last did this but here are the instructions that I was given by Xilinx:

1.    Start XSDB
2.    source jtagpins.tcl
3.    connect
4.    Set tag target to the cable you want to test, e.g. “jtag target 1”
5.    To assert reset do: "setpin SRST 0” or “setpin POR 0”
6.    To de-assert reset do: "setpin SRST 1” or “setpin POR 1"

I don't recall what the name of the target is and I don't have the hardware here so I can't try it out, sorry.

[AA_TO]

Not a problem - this is helpful. Thanks again!