We utilize an NXP Kinetis K02 microcontroller on Darsena, and the board has integrated hardware debug support utilizing an FTDI FT2232H device configured as a USB-based JTAG controller. We use OpenOCD to enable communication between a GDB debugger and the FT2232H device.
This article explains how we build & use OpenOCD on Windows 10 for Darsena in a Cygwin environment.
OpenOCD (On-Chip Debugger) is an excellent open source, community project for debugging and programming of embedded processors and FPGAs.
The FT2232H is a USB 2.0 Hi-Speed (480Mb/s) UART/FIFO/JTAG device. It has the capability of being configured in a variety of industry standard serial or parallel interfaces, and we use it on Darsena as a dual JTAG controller for both the NXP K02 and a Lattice ECP5UM FPGA.1
The NXP Kinetis K02 integrates an ARM Cortex M4 (ARMv7) and provides the following interfaces: I2C, SPI, UART, ADC, and DAC, all of which are used on Darsena.
JTAG is a 4-wire protocol defined by the IEEE (Std 1149.1-2013). The signals that comprise the Test Access Port (TAP) are TCK, TMS, TDI, and TDO. Various implementations also make use of additional pins for test and programming (i.e., TRST). Support of these additional signals can be accomplished with the FT2232 device through general purpose I/Os.
We build & run OpenOCD in a Cygwin shell. Cygwin is an excellent solution for having a Linux environment on a Windows 10 OS. In addition to OpenOCD, we use it extensively as an X windows server and secure shell (SSH) for networking with Linux PCs from a Windows desktop.
Installation of Cygwin is simple, but choosing the right packages can be tricky. We suggest that you follow the instructions on the Cygwin homepage, and here is a summary of the steps we use:
- Download and run/install setup-x86_64.exe (64-bit installation).
- Choose "Install from Internet" as the download source.
- Install the packages listed below.
- Let the installer create a Cygwin terminal on the Desktop and then launch the terminal / shell after installer finishes
Cygwin Devel packages to install:
Build OpenOCD from Source / Git Repo
From the Cygwin terminal:
$ mkdir -p /build; cd /build $ git clone https://git.code.sf.net/p/openocd/code openocd Cloning into 'openocd'... remote: Enumerating objects: 60802, done. remote: Counting objects: 100% (60802/60802), done. ...
$ cd openocd $ git log commit bbdb820c82d65cd11abdc329eaa91d410690436e (HEAD -> master, origin/master, origin/HEAD) Author: Tim Newsome ... Date: Mon Apr 8 14:06:04 2019 -0700 flash/fespi: Use COMMAND_PARSE_ADDRESS ...
There is always the potential to find new bugs when working with the bleeding edge. However, if we find strange bugs, we can backtrack to a previously known good commit or release. We found the commit on the master branch shown above to work for us.
We found that there were a few code tweaks required to build OpenOCD on Cygwin, and we created a patch file. Download it to /build/openocd, review it, and apply it:
$ git am < openocd-for-cygwin.patch
Now we'll build OpenOCD in it's own build sub-directory:
$ cd /build/openocd/ $ ./bootstrap + aclocal + libtoolize --automake --copy + autoconf + autoheader + automake --gnu --add-missing --copy ... $ mkdir build $ cd build $ ../configure --enable-ftdi ... OpenOCD configuration summary -------------------------------------------------- MPSSE mode of FTDI based devices yes ST-Link JTAG Programmer yes (auto) TI ICDI JTAG Programmer yes (auto) Keil ULINK JTAG Programmer yes (auto) Altera USB-Blaster II Compatible yes (auto) Bitbang mode of FT232R based devices yes (auto) Versaloon-Link JTAG Programmer yes (auto) TI XDS110 Debug Probe yes (auto) OSBDM (JTAG only) Programmer yes (auto) eStick/opendous JTAG Programmer yes (auto) Andes JTAG Programmer yes (auto) USBProg JTAG Programmer no Raisonance RLink JTAG Programmer no Olimex ARM-JTAG-EW Programmer no CMSIS-DAP Compliant Debugger no Cypress KitProg Programmer no Altera USB-Blaster Compatible no ASIX Presto Adapter no OpenJTAG Adapter no SEGGER J-Link Programmer yes (auto) $ make $ make install $ which openocd /usr/local/bin/openocd
Configuring OpenOCD Operation with Darsena
You'll want to connect your Windows PC to Darsena via a USB cable and provide power to the unit. See the figure below and Getting Started with Darsena for more details. Keep in mind that the K02 is connected to the second port (B) of the FTDI FT2232H. Also, Darsena utilizes the FTDI device without a dedicated external ROM, so its signature remains the device's factory default:
$ lsusb | grep FT2232 Bus 002 Device 002: ID 0403:6010 Future Technology Devices International, Ltd FT2232C Dual USB-UART/FIFO IC
Create "darsena.cfg" in /build/openocd/tcl/interface/ftdi. Note that we specify "ftdi_channel 1" for Port B.
# # Darsena # interface ftdi ftdi_channel 1 ftdi_vid_pid 0x0403 0x6010 # Every pin set as high impedance except TCK, TDI, TDO and TMS ftdi_layout_init 0x0008 0x000b # nSRST defined on pin CN2-13 of the MiniModule (pin ADBUS5 [AD5] on the FT2232H chip) # This choice is arbitrary. Use other GPIO pin if desired. ftdi_layout_signal nSRST -data 0x0020 -oe 0x0020
Also, create a launch script (k02.sh) in /build/openocd:
#!/bin/sh openocd -f tcl/interface/ftdi/darsena.cfg -f tcl/target/kx.cfg
Make sure the script has executable permissions:
$ chmod +x k02.sh
Note: add a -c "bindto <host ip address>" after kx.cfg in your launch script if you plan to use a different machine to launch the IDE / run GDB.
We currently rely on Zadig to make changes to our Windows 10 USB driver installation. We are using a dual-port FT2232H. Port A is routed to the FPGA JTAG, and Port B is routed to the K02 JTAG. Therefore, we want to use OpenOCD with Port B to debug the K02.
We're following the Zadig basic usage instructions documented here. Our goal is to replace the FTDI driver on Port B with the Microsoft WinUSB driver, so OpenOCD and libusb can communicate with the FT2232H Port B JTAG controller / device.
The figure below shows our Device Manager before running Zadig. COM5, COM6, and USB Serial Converter A and B represent the drivers for the two FTDI ports.
The next figure is the Zadig application. In order to see our FTDI device, we chose "Options->List All Devices". We selected Interface 1 for Port B. After selecting the device, we clicked "Replace Driver".
The figure below is our Device Manager after running Zadig. You can see that COM6 and USB Serial Converter B disappeared. In its place is "Dual RS232-HS", which represents a WinUSB driver.
We're ready to run openocd, so run the k02.sh script we created earlier (from /build/openocd):
$ ./k02.sh Open On-Chip Debugger 0.10.0+dev-00808-gdea90ae4 (2019-04-28-17:21) Licensed under GNU GPL v2 For bug reports, read http://openocd.org/doc/doxygen/bugs.html Info : auto-selecting first available session transport "jtag". To override use 'transport select <transport>'. Info : add flash_bank kinetis kx.pflash adapter speed: 1000 kHz none separate cortex_m reset_config sysresetreq Info : Listening on port 6666 for tcl connections Info : Listening on port 4444 for telnet connections Info : clock speed 1000 kHz Info : JTAG tap: kx.cpu tap/device found: 0x4ba00477 (mfg: 0x23b (ARM Ltd.), part: 0xba00, ver: 0x4) Info : MDM: Chip is unsecured. Continuing. Info : kx.cpu: hardware has 6 breakpoints, 4 watchpoints Info : kx.cpu: external reset detected Info : Listening on port 3333 for gdb connections
Note the line above Listening on port 3333 for gdb connections. This is what we'll connect to with GDB inside our IDE.
Now, start your IDE of choice and open or start a test C project. In this article, we assume you are using NXP's MCUXpresso.
Open Debug Configurations: Run -> Debug Configurations
Create a new configuration under "GDB Hardware Debugging" and set up the debugger tab as shown in the figure below. In our case, we run the IDE on a different PC than OpenOCD, so we specify the IP address of the machine where openocd is running.
Configure your "Startup" settings as shown:
When you're ready, click "Debug". You should see both the IDE and the openocd terminal window update. If you have errors, please report them below, and we'll try our best to help you.
- Darsena supports multiplexing FT2232H Port A with the FPGA JTAG and a UART. For more information see Darsena Hardware Specification.