Subject:
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RE: brickos 090 problem no program download with CONF_LNP_FAST
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Newsgroups:
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lugnet.robotics.rcx.legos
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Date:
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Wed, 30 Apr 2008 22:36:52 GMT
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Reply-To:
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<dickswan@sbcglobal.=spamcake=net>
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Viewed:
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29856 times
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Somewhere in the bowels of the header files within the RCX SDK is a list of
"IODEVICE control commands" which does include description of messages
required to change baud rate on the USB tower. I am assuming you're not
using the LEGO Windows DLL which has an easier interface to use.
It's quite a while since I "played" with this code. But I did have 4800
working fine with USB tower as long as you had the complimentary version of
the RCX. Once I started using AC adaptor RCX version almost exclusively, I
pretty much stopped using it.
The other thing you'll find if you using "fast" download mode and avoiding
the "double byte" transmission is that messages with a significant inbalance
of ones or zeroes won't work so well. There's not enough transitions bit
transitions for the serial port hardware to recover / sync to a proper
clock. I "solved" that particular problem by dynamically adjusting the size
of the download packet if it looked like the bits were "unbalanced". The
header bytes (0x55, 0xFF and 0x00) were enough to periodically allow the
clock syncing.
-----Original Message-----
From: news-gateway@lugnet.com [mailto:news-gateway@lugnet.com] On Behalf Of
Jochen Hoenicke
Sent: Wednesday, April 30, 2008 7:51 AM
To: lugnet.robotics.rcx.legos@lugnet.com
Subject: Re: brickos 090 problem no program download with CONF_LNP_FAST
<<snip>>
I just checked the source code. There is no speed setting for usb
tower in the code. If you look into firmdl3 you also find that fast
mode is disabled for USB, because it doesn't work. I think the USB
tower sends at 2400 baud and there is no known way to change it.
Remember that 4800 baud mode was never used by the official LEGO
firmware or download programs.
I have no idea how you can change baud rate (is this even possible?)
or carrier frequency on the USB tower. AFAIK the transmit carrier
frequency on the RCX is set by carrier_init in lnp-logical.c to 38
KHz. If I understand Dick Swan's post right, one should change it to
76 KHz for RCX 2.0. I think it should be possible by setting T1_CORA
to 0x0D instead of 0x1A.
Best regards,
Jochen
--
Jochen Hoenicke, http://hoenicke.ath.cx/rcx/
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