JTAG questions!

[luis23]

Posted on June 20, 2006 at 16:23

JTAG questions!

[luis23]

Posted on May 08, 2006 at 11:20

Hi guys,

do you have any ideas for this questions? I was not able to answer them by reading the datasheets: 1. Is it possible to build a JTAG chain with an FPGA and other devices? It seems that STR710 needs some additional lines for debugging (nJTRST, DBQRQS, nRESET), so it seems to be not so easy to build the chain. 2. Is it correct that the STR710 JTAG interface can be used for debugging and programming, but not for boundary scan? 3. Do you have any additional information about JTAG besides STR71x Microcontroller Reference Manual (http://www.st.com/stonline/books/pdf/docs/10352.pdf) and AN2099 Guidelines for connecting via JTAG to STR71x (http://www.st.com/stonline/books/pdf/docs/11125.pdf)? Any additional information is more than welcome! Best regards, Luis

[hichem2]

Posted on May 08, 2006 at 11:25

Hi,

Boundary scan feature is not supported by the STR710 JTAG interface. Regards, Hich

[hichem2]

Posted on May 08, 2006 at 11:32

Hello,

You can find some additionnal information regerding the JTAG logic work on the ARM web site like the following: http://www.arm.com/support/faqdev/4170.html Regards, Hich

[omartos]

Posted on June 19, 2006 at 06:27

Hi there...

But is it possible to build a JTAG chain with the other devices (fpga)? If you can send the BYPASS command with the JTAG to the STR7x, why is not possible? Those signals lufisch talks about are not mandatory to build a JTAG interface, so I think you don't need them. Boundary scan is not supported as ST has not implemented the boundary scan chain 3 (boundary scan cells), but as described in the reference manual, chains 0, 1 and 2 are implemented, so is it possible with JTAG write an external Flash? Thanks

[omartos]

Posted on June 19, 2006 at 07:46

Dear RISC... thanks for your answer

the application is a board with a STR710FZ2 with 2 Mwords of external flash, 4 Mwords external RAM, FPGA to decode several CSx among other tings (but not implement a JTAG interface), audio, USB, Ethernet... I have been reading a lot regard JTAG interface, and I wanted to implement several tests using JTAG in my board to know if everything is ok on it (no short circuits, no open nets, chips properly powered...). Other things I wanted to do are: · program the external flash through JTAG (if possible and not too slow) · bypass the arm to program the FPGA · maybe bypass the ARM and the FPGA to program/configure any other JTAG compliant devices... What do you think about that options? Regards Oscar

[omartos]

Posted on June 19, 2006 at 10:02

hello

Yes, when I say ''bypass the arm to program the FPGA'' I mean exactly what you say. Maybe exists any standard tool to program/configure different devices in the JTAG chain (not for debug). Keep in mind that this board,in 3 months must be in production, and that department of my company must perform the operations needed to write the external flash, write the fpga, and whatever necessary to set-up the board. So, I understand that I can write an external flash using JTAG and using scan chain 0, is that correct? Thanks for your answer

[t_i_t_t_o]

Posted on June 19, 2006 at 11:47

Most JTAG debug interfaces (PEEDI, BDI2000...) can program internal and external FLASH, so can be used as FLASH programmers via the JTAG port. The programming speed may vary from slow when programing using direct IO addressing operations to very fast when using agent loaded in the targets RAM. Both ways are many many times faster than using the boundary scan method to program external FLASH chips.

[omartos]

Posted on June 20, 2006 at 14:14

What I would like to do is ease the tasks that must be performed to setup the board when in mass production.

I would like to use the same tool to program the FPGA and the external flash of the board, and the internal flash of the arm, as well... but I don't know if it is possible. I understand that writing the external flash using boundary scan method can be very slow, as you must send at least 3 cycles for each word that must be written, but t_i_t_o, what do you mean when you say that can be very fast using agent loaded in the targets RAM? You mean, write some kind of 'bootloader' in the RAM, and after that, send the contents of the external flash to the board using a RS232 (for example)? Thanks folks!

[t_i_t_t_o]

Posted on June 20, 2006 at 16:23

I don't think you will find single tool that will be able to program FPGA and FLASH effectivly (fast enough)...

Just an idea: if it is possible the CPU to program the FPGA you can write your user program to check if the FPGA is programmed and if it is no to program it. This way you will need to program only the FLASH and after first normal boot the CPU will program the FPGA... By agent I mean the way the JTAG tool access the CPU peripherals. I don't want this to sound as a comersial, but PEEDI is a very good choice if you are looking for a FLASH programmer because it can work as a stand alone programmer which is useful for mass programming.