RE: [uCsimm] timer availability

From: Thomas Peter-apt090 (
Date: Thu Jan 25 2001 - 18:13:08 EST

There are two timers on the dragonball, one high resolution and one low, though I don't recall the resolution of the low one. I made a handful of changes, the first was moving the task scheduler to the low resolution timer. Then I changed the interrupt handling code so interrupts could be properly prioritized and so the high res timer could interrupt all other interrupts. I wrote a system call that allows me to pass data from a user application into the kernel, where the the interrupt handler resides. The user does the networking and monitors where the kernel is in a modulus buffer which it then feeds out on the ethernet. I also fiddled with the phase lock loop in order to get the precise 8khz I needed. My dragonball is running at around 24mhz for the duration of the capturing. You might be able to use the realtime linux stuff that has been around, but when I needed it networking didn't work and I didn't want to figure out how to make it work, but it might be ok for you!
. I'd be happy to give you the code I wrote as a .diff, but I don't really know how to make a proper one. Basically you would be able to put code into an interrupt handler, pass data to and from it, set the resolution of the timer, and still have a multitasking networkable device. If you or someone else can tell me how to make a diff for you I will. I have all the kernel code still in /opt/uClinux, so I would need to install 2.0.38pre7(from the CD) and diff the two of them. I need to know how to direct the destination directory of the install from the CD and what command to type ie, diff /opt/uClinux /opt/untoucheduClinux >diff.diff. If someone can supply me with that information I would be happy to help. Keep in mind that it is a hack job in places. I didn't always want to take the time to figure out how the kernel passed information through 50 data structures, so I just did what I needed to do to make my task work. It is just a lucky coincidence that this is your t!
ask as well.


-----Original Message-----
From: []
Sent: Thursday, January 25, 2001 3:06 PM
Subject: RE: [uCsimm] timer availability

Thanks, Peter -

What kernel changes did you make? That is exactly the sort of thing I'm
worried about having to do.

-- Ralph

> From Thu Jan 25 12:25 PST 2001
> Delivered-To:
> From: Thomas Peter-apt090 <>
> To: "''" <>
> Subject: RE: [uCsimm] timer availability
> Date: Thu, 25 Jan 2001 14:16:31 -0600
> Sender:
> Reply-To:
> There is a high resolution timer. I have been able to achieve about a 125uSec resolution with the simm and some kernel changes I made. I am sure that the simm can handle it. I have it reporting data it collects in realtime over the ethernet so it should be easy to dump it back to a host machine for displaying on the web or whatever.
> Peter Thomas
> -----Original Message-----
> From: []
> Sent: Thursday, January 25, 2001 1:53 PM
> To:
> Subject: [uCsimm] timer availability
> Is there a hardware timer available to user programs on the uCsimm? I
> need to measure the period of a pulse train (~1-60 sec/pulse, 0.1 sec
> resolution) and post the measurement to a CGI script on a webserver
> (to put the measurements in a database). Before I go building a little
> microcontroller circuit to send RS-232 data to the uCsimm, I'd like to
> know if I could do it all with the 68EZ328 under uClinux.
> Thanks!
> -- Ralph
> ===================================================================
> | Ralph Stirling | Project Engineer |
> | | Walla Walla College |
> | | School of Engineering |
> | 509/527-2071 | 204 S.College Ave |
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