Re: [Balloon] Re: JTAG hassles

Top Page
Attachments:
Message as email
+ (text/plain)
Delete this message
Reply to this message
Author: Steve Wiseman
Date:  
To: Balloon
Subject: Re: [Balloon] Re: JTAG hassles
On Mon, 13 Nov 2006 15:50:38 +0000, Wookey <> wrote:

>> So, fundamentally I have two significant problems:
>>
>> 1) the lart dongle works on xios for bootldr, but neither of the CPLD
>> ones do, on either of the parallel ports, so I can't bringup a board
>> on that box - I have to get my laptop out. Any clues as to why this
>> might be would be appreciated.


Have you stuck a 'scope on it?
Running LPT ports down cables longer than, wild guess, a foot, is enough
to make me worry about termination issues.
Any extension cable on the port is brave - are you running longer cables
fro the desktops than the laptop?
It's also possible that the laptop has nice low-power drivers on its
ports, slewing slower and causing less pain.

>> 2) Only the steve dongle is working for me for CPLD programming.


Yay! High quality bodging from Steve...

>> The
>> new xilinx ones which should work don't. I'm not sure which bit of the
>> system is wrong.


I detest LPT JTAG with a passion. However, it does sound like you ought to
come round for a debug session.

> OK. It turns out that the problem with this was that it needed a
> pull-up on port_en was too feeble, and wasn;t pulling up far enough.
> Connecting the switch to VDD3 for a good hard pull made it work fine.
> This is 'S?' on the schematic:
> http://balloonboard.org/hardware/JTAG/xilinx/jtag_dongle_schematic.PDF


Yay.

>> 3) I can't seem to use the new bflash jtag code on balloon2 at all,
>> either in bflash or jflash mode. It is working for anyone else?


I've not tried.

Steve