I am able to connect to the gdb server that openocd listens on, but looking at the registers, and instruction pointers etc. If someone is willing to instruct me on how to build a config file for this chip by issuing urjtag commands and scanning the chips pins, im willing to try it and post the results for the benefit of the community. The jtag header is usually located near the flash chip. All the code that i used here is present on my jtagduino github repository i have an olimex stm32p152 board, and i wanted to connect to its jtag interface with my arduino uno. Inside the zip file download for the hairydairymaid wrt54g debrick utility v48 there is a pdf file that describes the software and how to use it. This is a fork of the work the ethzurich did on the advanced debug interface from opencores. Blog how i bricked and debricked my linksys wrt54gl router. Its free software and the credit goes to hairydairymaid a.
All you need is a short adapter cable, a piece of software, and of course a jtag header on your devices circuit board. Most arm processors found in embedded application have a jtag interface, for debugging hardware and software while the system is running. In most cases it is a 12 to 14 pin header which must be assembled with 2,54mm pins. Generally yes you can jtag as a debugger has absolutely nothing to do with what software you happen to be running on that processor. These engineers have no control over th e design decisions that are made in the adiv5 interface implementation to which they connect, but must be able to. By adding xjanalyser functionality to standalone xjdeveloper, the xjtag development system is an integrated development environment ide for the development and debugging of jtagbased test and programming systems the xjtag professional development system is supplied with an additional xjio test extension board that allows you to improve test. It provides a graphical view of jtag chains, giving you complete control, on a pinbypin basis, of both pin state either driven as an output or tristated as an input and pin value either high or low when driven. The most famous software for jtag is probably the linksys debrick utility by hairydairymaid aka lightbulb. Universal jtag library, server and tools discussion. He said that he flashed the killer and reseted the modem, but after this, the 4 ethernet leds and the internet led still on and the other leds ar. This software was found on the downloaduk website, along with other helpful jtag tools. Additionally, when depressed, the reset button asserts this pin low.
The jtag software is still in active development by tornado on ddwrt forums as tjtag. Physical connection to tap controller is made in software bitbanging mode. Exactly for this purpose, in 1985 the jtag joint test action group interface was created, a standard ieee 1149. Virtually everyone who uses this software opts for an unbuffered cable, and the software itself, by default, expects this type of. And jtag was explicitly designed to have manufacturer extensions in for debuglike purposes, so its not comparable to spi etc.
This preface introduces the arm debug interface architecture specification adiv5. System software debug with jtagxdp and event trace by robertmuelleralbrecht, published on february 3, 20 this translates directly to a more complex software stack, that has its own challenges for guaranteeing consistent reliability throughout the devices life cycle. Diygadget provides solderless solution for these routers. Then some debug and test interfaces integrated into the chips processor, microcontroller, soc, fpga, etc. Debugging using segger jlink jtag boundary devices. Some tutorials mostly those written for wrt54g routers used a 10 pin connector for the jtag cable, others used the 12pin one. The jt 5705 series offer a unique combination of jtag tap controller tester interfaces plus digital and analog io in compact desktop package. This allows easy adaptions to support multiple bus interfaces. Jtag is essentially a hardwarelevel communications interface. It specifies the use of a dedicated debug port implementing a serial communications. He specifically talks about using an unbuffered cable and pointedly notes that the cable he uses does not tie pin 1 of the jtag header to anything. Joint test action group, referring to ieee standard 1149.
Debugging a system without making any assumptions about the software running on that system. If your router like the linksys wrt54g series already has the standard 12 pin jtag pads on the pcb, you mostly like do not need to solder wires on your pcb. Communication is done via standard tcpip gdb remote serial protocol. However, this means that jtag is likely being disabled in software.
Jtagxdp debugging for firmware, os level system and device driver debug, using a jtag interface is the most commonly used method in the embedded intelligent systems world. Otherwise you many need to solder idc headers on your boards jtag pads or holes. Usbjtag nt provide faster programming speed and wider range of target support. I think reading too much into the acronym is a mistake as with many acronyms. Usbjtag nt usbjtag nt programmer spi flash programmer. Free jtag software from intellitech enables you to use the power of internal jtag silicon instruments with a commercial quality tool. Solve problem with debugging linksyswrt54gl with jtag. Where you can get into trouble is the cache, for example if you stop the processor want to change some instructions in ram, and restart, the changing of instructions in ram is a data access, which does not go through the instruction cache but the data cache, if.
Conversely, i never use jtag for board level testing, only for doing debug. Use the mixedsignal features to measure power supplies, clock frequencies or test dacs and adcs. But linksys routers should all have the same layout, right. I didnt find an official homepage, so i got the sourcecode from the ddwrt people. This means that whenever the jtag adapter was connected to the jtag header, the system thought that the reset button had been pressed. Essentially, you can use jtag hardware to send particular commands to the debug unit of your microcontroller, but the actual debug commands are cpuchipetc specific. The hairydairymaid utility is designed to debrick wrt54g routers. Arm debug interface architecture specification adiv5. Two corner cases of jtag software debug implementation first case. I have a nonsilabs jtag adapter based on an ftdi chip, which will scan the jtag interface and does find the f122 i cant however, seem to get the silabs usb debug adapter to talk to the f122 jtag is selected in the software. Ddwrt forum view topic unbrick wrt54g v8 with jtag. Actually i tried several address big boundaries, including 0x1fc00000 but none replies.
Gdb remote stub backend for debugging an embedded arm system via jtag common hardware debug interface. In this demonstration, i soldered 12 pin header on my router wrt54gs. I have a usb debug adapter which works fine using c2 and an f340. Connect the cable to the pc then the wrt150n jp1 and power up the wrt150n. Jtag is a useful tool that allows customers additional debugging options. The original openwrt hairydairymaid jtag software wrt54g does work with ti ar7 via custom configuration options using the very poormans xilinx buffered parallel port cable. Urjtag is free software, covered by the gnu general public license, and you are welcome to change it andor distribute copies of it under certain conditions. Unbrick wrt54g v8 with jtag a friend of mine bricked his brand new linksys wrt54g v8 while trying to install dd wrt. Since i dont have enough experience with jtag, mips and urjtag to debug the issue myself, i looked for another solution.
Jtag named after the joint test action group which codified it is an industry standard for verifying designs and testing printed circuit boards after manufacture jtag implements standards for onchip instrumentation in electronic design automation eda as a complementary tool to digital simulation. Qbprogrammer qbp is a software tool that is used to erase, write, and verify programs on the target system or fa adapter, on which an nec electronics singlepowersupply on chip flash memory microcontroller is mounted, by using the onchip debug. Riscv core debug mechanism comparison github pages. Software run on a bare metal system that allows for selfhosted debug. Segger was kind enough to send us a jlink plus probe for us to test. Jtag vpi client driver for openrisc reference platform soc. I wrote a couple of posts about it, and today i managed to connect it to a real target. Create a project open source software business software top downloaded projects. Now the wire is ready now the circuit board has to be prepped as well. Fourpin plus powerground interface designed to test connections between chips. This is a mirror of the original hairydairymaid jtag debrick utility v4. System software debug with jtagxdp and event trace. This program is for debricking the wrt54ggs routers. Special thanks to luniz2k1, for his excellent testing and reporting skills.
Add your own capability through use of corecommander fpga our generic bridgetranslator system. Ddwrt forum view topic wrt54gtm nonjtag cfeupdater. Configuration is performed by manipulating a state machine one bit at a time via tms pin, then transferring one bit of data in and out per tck clock via. This blog post will describe how to setup your environment and use the jlink to debug during both uboot and kernel development. As the links above demonstrate, there are many hardwaresoftware pairs thatll get you up and debugging. As of 12 september 2006 the most recent version is v4. This article covers the use of the intelr system debugger for system software stack debug on android based ia32 and intelr 64 devices. Reenabling jtag and debugging the wrt120n devttys0. Jtag flash programmer software free download jtag flash. Ujmodem is a software based on usb jtag nt and provide better ui as well as continue support cli.