Re: JTAG Problem

Hi Chris!

As you can see, your connection works, but not very well. First of all: It would be amazingly euphemistic to call you cable crappy! It's absolutely  minimalistic and doen't hold a single rule for electrical design: One cannot convert voltages by adding some resistors; you can only prevent your hardware from blowing up. This could be caused by other tasks accessing the port without locking it or something similar. First, you should stop all tasks, that do not need to run. I've never looked inside the jtag-code, but this way you can make sure, that nothing uses your port and no cpu time will be wasted, so that even time critical apps can run cleanly. Additionally you could remove all parport-modules from the kernel (lp, parport, parport_pc...) and tell the jtag-utilites to access you port directly without any kernel drivers using the io-bus itself (see "cable" manpage). And still, it might not be working yet: The last reason for your problem could be a burn-up protected parallel port. Most modern printer ports have resistors directly behind the connector to protect every single line from breaking when connected to a different voltage than its very own. Theese about 1k sized resistors add to the jtag-resistors and get highly above the suggested values. The other way around is even worse: one can try to control a 5Vline using 3V, but this'll get very slow, if it even works at all (depending on the hardware inside your pc). You could try to use some old and thus unprotected hardware to flash your device or try to explicitly convert the port voltages by using a MAX212 or something similar.
(http://www.maxim-ic.com/quick_view2.cfm?qv_pk=1051&ln=)
Before using this IC you should check the speed of your jtag-iface and compare it to the maximum rating named in the data sheet.
(http://pdfserv.maxim-ic.com/en/ds/MAX212.pdf)
I never cared about the speed of jtag-connections, but in case of a too high frequency you'll need to find a different converter or build one yourself using some appropriate (e.g.) transistors and a few additional components.


Good luck!
  Ralf
PS: Try using a different machine first :-)


-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]] Im Auftrag von Chris Martin
Gesendet: Freitag, 26. November 2004 16:48
An: [email protected]
Betreff: [Simpad-general] JTAG Problem

Hi JTAGers,

I'm trying to revive my SIMpad with JTAG after killing it with the 
hh.org bootloadr.

When I run detect I get different results each time. Whenever I get a 
reasonable output I move on to detectflash and I always get "Flash not 
found!"

jtag> cable ppdev /dev/parport0 DLC5
Initializing Xilinx DLC5 JTAG Parallel Cable III on ppdev port /dev/parport0
jtag> detect
Device Id: 00100100100100110000000000010011
  Manufacturer: Intel
  Unknown part!
jtag> detect
Device Id: 10011001001001100001000000010011
  Manufacturer: Intel
  Part:         SA1110
  Stepping:     B5
  Filename:     /usr/share/jtag/intel/sa1110/sa1110
jtag> detectflash
ROM_SEL: 16 bits
Flash not found!
jtag> detectflash
ROM_SEL: 16 bits
Flash not found!

I've checked and double-checked all contacts from the test grid to the 
end of the JTAG connector. Everything is O.K.
Oh yeah, I made my own cable from the instructions at sf.net. And yes it 
is very short (~20 cm.).

I would be thankful if someone can help me out on this one. Otherwise my 
SIMpad days are of the past.

Chris

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