Typo in jtag.c

[kevinhikaruevans]

Was just reading over jtag.c and noticed this:

Bus_Pirate/Firmware/jtag.c

Lines 102 to 108 in b580ca9

	uint16_t words = 0;
	while (jtag_read_bit() == LOW) {
	words++;
	if (words < 250) {
	break; // 250 device timout/limit...
	}
	}

Should that be words > 250? It will always break on the first loop iteration.

[kallisti5]

err.. yeah. That looks like a bug. It was likely a while (words < 250) at some point.

[ironiridis]

Fixed in dd7fbb0?

[MrAureliusR]

I'm amazed this wasn't caught sooner. Wouldn't this have totally broken JTAG functionality?

[USBEprom]

@yodaldevoid @ironiridis @everyone

Starting from https://github.com/BusPirate/Bus_Pirate/archive/dd7fbb0fedd27c08b9c33501ebbe4b28d8085cba.zip provided by Gabriel Smith aka yodaldevoid, I have built test firmware busPirate_JTAG_UNSAFE_1.hex which has hardware I2C freed and busPirate-JTAG_SAFE_1.hex which has not.
Both of them are firmware for Bus Pirate v3 (BPv3).
The two firmwares can be found here:

http://dangerousprototypes.com/forum/index.php?topic=8498.msg71171#msg71171

About the SAFE and UNSAFE version, please read these:

http://dangerousprototypes.com/forum/index.php?topic=8760.msg70072#msg70072
http://dangerousprototypes.com/blog/2009/08/10/bus-pirate-hardware-i2c-added/
http://dangerousprototypes.com/blog/2009/08/07/find-your-bus-pirates-pic-revision/

Sadly at this moment I can not verify the functioning of the JTAG part, so I ask the courtesy to anyone who is able of doing it to try one of the two firmware and give a response, thanks.

[akhepcat]

Hopefully this leads to a BPv4 fix, because I'd love to have JTAG on my v4....

[USBEprom]

@akhepcat ; @leif

busPirate_JTAG_UNSAFE_1.hex and busPirate-JTAG_SAFE_1.hex are both firmware for Bus Pirate v3 (BPv3).
The two firmwares can be found here:

http://dangerousprototypes.com/forum/index.php?topic=8498.msg71171#msg71171

Sadly I can not verify them for the functioning of the JTAG part, therefore it is need that someone verify and report if they work or not.
Thanks.

[USBEprom]

@gdamjan

At first I did not understand the meaning of your message, but now I understand it and I must tell you that you have done an excellent job providing the community with a great service, you really had an excellent idea!
Thank you very much Sir!

[USBEprom]

@akhepcat ; @leif

#152

https://github.com/gdamjan/Bus_Pirate/releases/tag/v.test

[akhepcat]

@USBEprom -
HiZ>m

1. HiZ
2. 1-WIRE
3. UART
4. I2C
5. SPI
6. 2WIRE
7. 3WIRE
8. KEYB
9. PIC
10. DIO
    x. exit(without change)

(1)>no mode change
HiZ>
HiZ>i
Bus Pirate v4
Community Firmware v7.1 - goo.gl/gCzQnW [HiZ 1-WIRE UART I2C SPI 2WIRE 3WIRE KEYB PIC DIO]
DEVID:0x1019 REVID:0x0003 (24FJ256GB106 A5)
http://dangerousprototypes.com

I don't see the JTAG enabled here, though everything else seems to be working fine.

[USBEprom]

@leif ; @akhepcat

Thank you for your reply.
As I wrote, sadly I do not have a Bus Pirate v4 for testing.

[akhepcat]

@USBEprom Yes - I do, so i'm testing as I can. If you enable it, I can test it. I just can't build it

[USBEprom]

@leif ; @akhepcat @ALL

Although I do not have a Bus Pirate v4 to test it, I have built a firmware for that device where the JTAG option is enabled.
I do not know if it is working or not, I provide it only for testing purpose.
The package contains the configuration.h file used to compile the firmware, whose optimization level used to build it is option 1.
Please let me know if there is any problem or if it is need to make specific changes to the configuration.h file.
Thanks!

FW_BPv4_JTAG_opt1.zip

[gdamjan]

@akhepcat ; @leif

#152

https://github.com/gdamjan/Bus_Pirate/releases/tag/v.test

those builds there don't have the jtag patch included (yet). Let me work on finishing up #152 and I can see about the other stuff later.

[akhepcat]

@USBEprom ( @gdamjan ) Just for the FWIW:
Flashed the "opt1" firmware on my v4, but still no JTAG in the menu.

Looks like i'll be waiting for the jtag patches after #152 is complete.

Thanks.

[USBEprom]

@leif ; @akhepcat

As I have already written, I do not own a Bus Pirate v4, I only have a Bus Pirate v3.
In any case I do not think that the JTAG item should appear in the menu, simply JTAG support can be active or not depending on what is set during compilation through the file config.h.
Firmware FW_BPv4_JTAG_opt1.hex that I provided here definitely has JTAG support enabled, as it is also possible to see from its config.h file attached.
Even the firmwares for the Bus Pirate v3 that I shared on dangerousprototypes.com forum have JTAG support enabled, but as far as I can see the wording JTAG does not appear in the menu.
Please, take a look at these:

http://dangerousprototypes.com/docs/JTAG

NOTE: As of v5.9 the JTAG terminal library was moved to the Bus Pirate bonus/extras firmware.

Bus Pirate firmware v5+ (main firmware) includes support for the OpenOCD JTAG debugger instead, this is a much better option.

http://dangerousprototypes.com/forum/index.php?topic=2207.0

The ONLY THING removed from the firmware is JTAG terminal mode. NOBODY used JTAG terminal mode, and it will NOT help you to flash a device. It is not a console concept either. It is a way to entering raw byte values into JTAG registers. If you learned the flashing protocol (by hand), you could type in the raw byte values (100,000s of them) into the terminal mode, but nobody would do this, applications like OpenOCD automate it.

From http://dangerousprototypes.com/docs/Bus_Pirate

Several applications can use the Bus Pirate as a programmer or debugger.

JTAG

The Bus Pirate is a slow serial port device intended for human-speed interaction. It was NEVER intended to do JTAG duties. Because it's open source, cheap, and versatile, the community hacked various JTAG features into it. They're great in a pinch, but no substitute for the real thing!

The Bus Pirate supports JTAG in three ways: with the OpenOCD debug application, as an XSVF player, and through a user-mode terminal interface.
JTAG and OpenOCD

The Bus Pirate is supported as a JTAG programmer/debugger by OpenOCD. If your target is supported by OpenOCD it may work. Slowly :) You will need to use a Bus Pirate firmware version which supports the binary JTAG protocol — not all do.

Note that the above is about binary JTAG / OpenOCD support. JTAG terminal mode is not enabled in any of the above firmwares (not even 5.9-extras, even though it was advertised to be enabled in there at some point).

JTAG terminal mode

The -extras firmware has a the old user terminal JTAG mode from the Hack a Day demo. This was removed from the main firmware because nobody used it - it isn't particularly useful to enter JTAG commands manually. (OpenOCD uses the binary JTAG mode, which is different from the user terminal JTAG mode.)

Talking about the Bus Pirate v3, as of v5.9 the JTAG terminal library has been removed and moved to the Bus Pirate bonus/extras firmware.
I am not sure how things stand for Bus Pirate v4, though.
Bus Pirate v3 firmware v5+ (main firmware) includes support for the OpenOCD JTAG debugger instead, this is a much better option.
I believe that the same thing, excluding numbering of the firmware, also applies to the Bus Pirate v4, so no JTAG item does exist in the menu.
But I repeat that I have never had or used a Bus Pirate v4, so I am not an expert on the subject.
Learn more here:

http://dangerousprototypes.com/forum/index.php?topic=4550.0
http://dangerousprototypes.com/docs/Bus_Pirate_firmware_change_history
http://dangerousprototypes.com/forum/index.php?topic=4428.0

About patch, the firmware FW_BPv4_JTAG_opt1.hex I provided here and the ones for Bus Pirate v3 named busPirate-JTAG_SAFE_1.hex and busPirate_JTAG_UNSAFE_1.hex that I have shared on dangerousprototypes.com forum (http://dangerousprototypes.com/forum/index.php?topic=8498.msg71171#msg71171), all them have the one in jtag.c provided from Gabriel Smith aka yodaldevoid, as follows:

`@@ -102,7 +102,7 @@ void jtag(void) {'

 'uint16_t words = 0;'
 'while (jtag_read_bit() == LOW) {'
   'words++;'
   'if (words > 250) {'
     'break; // 250 device timout/limit...'
   '}'
 '}`

I do not know if that is enough, though, because at this moment I can not verify the functioning of the JTAG side.

[akhepcat]

Ah! I missed where they took the jtag console option out, and I was using that as the indicator for support. Mea culpa!

I hooked up my bp4 to my rPi, configured a local config file appropriately, and was able to get OpenOCD to talk correctly to the bp4.

I did notice that sometimes when closing, it didn't reset the configuration correctly, so I had to button-reset the bp4 before re-running OpenOCD - that's not a terrible workaround, though. The 'mode' LED lights up when things are working correctly, it seems.

i haven't hooked it up to an actual JTAG host yet, since i think i killed my pogoplug fully and I don't have anything else laying around JTAG capable and "disposable"

But so far it's looking pretty good.

[USBEprom]

@akhepcat

Thank you very much for sharing your experience, really much appreciated, thanks!
About OpenOCD with the Bus Pirate v3 I have never encountered any problems in communication, not even with firmwares that are not too recent, but I never got past this, so I think this is not enough to determine if the problem has now been solved or not.
Honestly I did not understand what the problem that generated this issue consists of, so I do not understand how to replicate it and possibly check if it still exists or not.