Subject:
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Re: time sampling under the rcx standard OS
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Newsgroups:
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lugnet.robotics.rcx.nqc
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Date:
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Wed, 21 Sep 2005 18:03:14 GMT
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Viewed:
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6251 times
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On Wed, September 21, 2005 11:49 am, Francois Bardet wrote:
> Hi Steve,
> As I'm quite new to BrickOS and to C programming, I'm sorry I'm not sure I
> understood what you meant, neither how you do this :
>
> > Well, in BrickOS, my loops usually execute at
> > 1kHz, so I usually just set
> > it to check the sensor, and set the motor every 1ms. So it just keeps
> > checking the clock.
>
> - Do you check the sensor at a higher rate, and only send a command to the motor
> at 1kHz ?
> - How do you get this command to be looping at 1kHz (I do not know yet how time
> is managed within BrickOS) ?
> - Is it better to run two tasks independently, one for sensor checking, and one
> for motor command sending ?
> Maybe you'd have a sample to show how you proces this ?
>
> Thanks, best regards,
>
> Francois
Here's a code byte from my LegWay code.
----
int MotorSpeedArray[32] = {1,3,2,0}; // Speeds
// ... later in the program...
if (sys_time>CheckTime) // check system timer - is it time to check sensors again?
{
L1 = ReadSensor(SENSOR_1);
L3 = ReadSensor(SENSOR_3);
MotorSetting = (((L1 - CenterPoint1) * AdjustSpeed / 8 + 8) + ((L3 - CenterPoint3)
* AdjustSpeed / 8 + 8)) / 2;
// check boundry
if (MotorSetting < 0) MotorSetting = 0;
if (MotorSetting > 16) MotorSetting = 16;
CheckTime = sys_time + 1;
}
MotorRunningValue = ((sys_time) >> 1 & 7);
motor_a_dir(MotorSpeedArray[(MotorSetting + MotorRunningValue)>>3]);
motor_c_dir(MotorSpeedArray[(MotorSetting + MotorRunningValue)>>3]);
----
The first part looks at the system time (I think the function is get_sys_time_up()
in the latest version of BrickOS). This function returns the current system time in
ms, so I just have it look at the sensor whenever the time changes.
The motor control is a bit harder to explain. It takes in settings from 0 (full
forward) to 16 (full reverse) and creates a PWM for some percentage of 8 ms.
Steve
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Message is in Reply To:
 | | Re: time sampling under the rcx standard OS
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| Hi Steve, As I'm quite new to BrickOS and to C programming, I'm sorry I'm not sure I understood what you meant, neither how you do this : (...) - Do you check the sensor at a higher rate, and only send a command to the motor at 1kHz ? - How do you (...) (19 years ago, 21-Sep-05, to lugnet.robotics.rcx.nqc)
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