Subject:
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Re: I2C device for the RCX
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 15 Jan 2003 09:59:05 GMT
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Viewed:
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1283 times
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Gunther Lemm wrote:
> Lepomux works with a serial protocol (5 bit preamble, 8 bit data,
> parity) based
> on a halfbit-clockspeed of 1 kHz. So compared to your I2C-driver it is
> dead
> slow (about 33ms/byte = 30 bytes/s).
Well, one reason for this is that I2C doesn't need a precise clocksignal
(thanks to Dick Swan for telling me, I totally forgot about it).
All the timer stuff shouldn't matter for the I2C device, so there should
be even higher speeds possible, dick swan thinks up to 75000 bits/sec.
(WOW, would be cool!)
I'm kind a busy right know, so i don't have the time to work on it. At
the end of the week I will start working on this, and see what I can get
out of it.
I think the lepomux has a more clocksignal based protocol: a unstable
clockpulse results in bad communication, so that would explain the
diffrence in speed.
> <snip>
>
> Some days ago we had another idea of how to transfer about 100 bytes/s
> without
> a kernel patch (that should even work with NQC).
whit NQC? thats intresting! This is even faster than what I got here
whit my BrickOS driver! I would surely like to know more about this! the
I2C device made a max transfer of 27 bits/sec(=about 3,4 bytes/sec(!))
whit NQC.
> Did you calculate the time needed to send/receive one of you I2C-bytes by
> looking at the H8 machine-cycles?
> Did you run any tests on the multitasking behaviour of the system?
nope, I didn't. Its a good idea to check out how long sending one byte
would take. maybe that will tell me more about the max transfer rate
possible on a sensor port.
And about the multitasking behaviour, since a stable clock signal isn't
needed, I don't think this will be a problem. At least, it shouldn't be.
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Message has 1 Reply:
 | | Re: I2C device for the RCX
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| (...) We'll first check it out before boasting about it ;) The whole thing won't work without some hardware modifications on the lepomux - so I'll tell you about it in two or three weeks. Gunther (22 years ago, 15-Jan-03, to lugnet.robotics)
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Message is in Reply To:
| | Re: I2C device for the RCX
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| (...) Lepomux works with a serial protocol (5 bit preamble, 8 bit data, parity) based on a halfbit-clockspeed of 1 kHz. So compared to your I2C-driver it is dead slow (about 33ms/byte = 30 bytes/s). This slow speed has two reasons: - it's possible (...) (22 years ago, 14-Jan-03, to lugnet.robotics)
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