Subject:
|
Millisecond timing
|
Newsgroups:
|
lugnet.robotics.handyboard
|
Date:
|
Fri, 30 Jul 1999 12:44:25 GMT
|
Original-From:
|
Landahl, Bill <bill.landahl@morganite&StopSpam&.com>
|
Viewed:
|
885 times
|
| |
|
|
I recently bought a Handy Board to use in acquiring time
measurements varying by one millisecond. The Handy Board has a clock speed
of 2kHz, therefore it should be able to measure down to one half
millisecond.
What I have found however is that the smallest time I am measuring
is 3 millieseconds. Ther is no code running except for the time acquisition
code. My question is, Will it be possible for me to get the one millisecond
time accuracy I want? Should I be using system interupts instead of just
reading system time? If so, how do I do that?
Below is the code I am running for the time acquisition.
int x;
int y;
float p;
float n;
float z;
void main (void)
{
while(1) {
if (digital(10)){ /* capture leading edge*/
while (x < 1){
n = seconds();
x++;
}
}
if (digital(11)){ /*capture leading edge*/
while (y < 1){
p = seconds();
y++;
}
z = p - n; /*floating point math- after data
acquired*/
printf("\nTime= %f",z);
}
if (start_button()){
x=0;
y=0;
reset_system_time();
}
}
}
--
MIME ATTACHMENTS DISCARDED:
1. Content-Type: text/html
Content-Transfer-Encoding: quoted-printable
Content-Length: 4169
|
|
Message has 2 Replies:
 | | Re: Millisecond timing
|
| The clock speed on the Handy Board runs at 2 Mhz, which is plenty fast enough for most things IF you run the right code. IC, used in its C implementation is too slow to catch anything at 1 ms reliably. However, there are a few simple work arounds. (...) (25 years ago, 30-Jul-99, to lugnet.robotics.handyboard)
| | | Re: Millisecond timing
|
| (...) See the Polaroid sonar code (from the HB web site) for an example of how to measure timing signals on the TIC3 channel. You initialize with: bit_set( 0x1009, 0x30 ); /* ddrd */ bit_set( 0x1021, 1 ); /* at tctl2, */ bit_clear( 0x1021, 2 ); /* (...) (25 years ago, 30-Jul-99, to lugnet.robotics.handyboard)
|
3 Messages in This Thread:
 
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
