JTAG firmware write

lgiordano2 · ‎2009-10-23

Posted on October 23, 2009 at 17:41

JTAG firmware write

lgiordano2 · ‎2009-10-07

Posted on October 07, 2009 at 19:48

Hi,

We are about to make a production of 2000-2500 devices using STR712. Usually we upload firmware using a PC and JTAG programmer.

To test our devices, we have our own testing device, which also has a STR712.

We would like to make the testing device to upload the firmware to a new blank device. We think our testing device can use some GPIOs to upload firmware using JTAG, just as a JTAG programmer do.

Does anybody have some information about this? May we use the SPI to connect to JTAG?

Best regards,

tomas23 · ‎2009-10-19

Posted on October 19, 2009 at 23:27

I am not sure if SPI can do it, as JTAG needs non-8-bit multiple of clocks for its scan chain.

jgoril · ‎2009-10-21

Posted on October 21, 2009 at 11:55

Quote:

On 20-10-2009 at 02:57, Anonymous wrote:

I am not sure if SPI can do it, as JTAG needs non-8-bit multiple of clocks for its scan chain.

This can be simply solved. E.g. chain_2 has 38 bits. You can use 40 clocks (5x8 bytes), just keep in mind that:

- for input (TDI): relevant 38 bits must be clocked in at the end of transfer

- for output (TDO): relevant 38 bits are clocked out at the beginning of the transfer

So you need to add some padding bits before your input and discard some bit after the output. That's all :)

kleshov · ‎2009-10-23

Posted on October 23, 2009 at 17:41

You might be able to get some information by looking at OpenOCD source code:

http://repo.or.cz/w/openocd.git?a=tree

OpenOCD does support the STR71x family.