Subject:
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Re: Time available during 1 kHz system interrupt?
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Tue, 2 Nov 1999 17:15:37 GMT
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Original-From:
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Christopher Prosser <cprosser@acm.=SayNoToSpam=org>
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Viewed:
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779 times
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The controls are spread across a couple of files, mainly in libhb.c we get
/*
pulse width modulation control:
if off, all motors run at full speed
if on, speed bytes are used to determine motor speed
*/
void system_pwm_on() {bit_set(0x39, 0b00000100);}
void system_pwm_off() {bit_clear(0x39, 0b00000100);}
/*
printing to the LCD
WARNING: printf's will wedge once the print buffer becomes full
if system printing is disabled */
void system_print_on() {bit_set(0x39, 0b00000001);}
void system_print_off() {bit_clear(0x39, 0b00000001);}
in r22_ir.c
void ir_transmit_on();
void ir_transmit_off();
void ir_receive_off();
void ir_receive_on();
encoders.c enables and disables encodes.
Note: I'm not sure if these completely disable the code at the asm level.
In regards to what happens if you exceed 1ms, the pcode.asm has the
following comment:
System interrupt performs the following tasks:
*
* 0. sets up for next interrupt
* 1. increment system time
* 2. decrement "process_ticks". If zero, pokes
* BRN (branch never) into pcode_run loop, so that
* current process exits.
* 3. deals with LCD print.
* 4. does PWM stuff.
* 5. does shaft encoder stuff.
A quick read of pcode.asm dictates that memory location 0x39 is a set of bit
flags for all the functions you can control. bit_clear(0x39, 0x00) will turn
everything off. Here are the bit definitions
PRINTBUFFER EQU %00000001
IRDECODE EQU %00000010
PWM EQU %00000100
SHAFTENCODER EQU %00001000
-chris
----- Original Message -----
From: Bruce Moore <bamoore@bloomington.in.us>
To: <handyboard@media.mit.edu>
Sent: Tuesday, November 02, 1999 4:47 AM
Subject: Re: Time available during 1 kHz system interrupt?
> Interesting discussion but it raises a few more questions.
>
> Are there any (bad) side effects when user code that is inserted in the • ISR
> takes longer to execute than the 1 msec interrupt cycle. From experience
> it appears that the ISR runs on the next interrupt following the • completion
> of the current cycle. The only thing I noticed is that the PWM routines
> don't always calculate their next transition correctly but i figure that
> there are plenty of other things that are going on that I'm not watching
> (and that may eventually bite me).
>
> Chris: How do you turn off the things like IR and quad shaft decoding to
> get rid of the little overhead.
>
>
> ----------
> > From: Christopher Prosser <cprosser@acm.org>
> > To: Greg Starr <starr@unm.edu>; handyboard@media.mit.edu
> > Subject: Re: Time available during 1 kHz system interrupt?
> > Date: Monday, November 01, 1999 8:48 PM
> >
> > Hi Greg,
> > It all depends. Various features of the HB can be turned on and off to
> > change the amount of work done in the main ISR. By default the code uses
> > 300ms to execute. The file lib_hb.c provides the following:
> >
> > /********************************/
> > /*** System Interrupt Control ***/
> > /********************************/
> >
> > /*
> >
> > These functions allow you to turn on and off various features
> > controlled by the system interrupt routines. The more features
> > you turn off, the faster your code will run.
> >
> > On reset, the features have the following state:
> > pulse width modulation ON
> > infrared decoding ON
> > LCD printing ON
> > quad shaft decoding OFF
> > IR tranmission OFF
> >
> > This uses approx. 30% of total CPU time.
> >
> > Approximate benchmarks:
> >
> > x Feature % of CPU
> > ------- --------
> > PWM 3
> > IR decode 11
> > LCD printing (active) 8
> > LCD printing (inactive) 1
> > quad shaft decode 5
> > IR transmission 1
> >
> > */
> >
> >
> >
> > -chris prosser
> >
> >
> > ----- Original Message -----
> > From: Greg Starr <starr@unm.edu>
> > To: <handyboard@media.mit.edu>
> > Sent: Monday, November 01, 1999 7:19 AM
> > Subject: Time available during 1 kHz system interrupt?
> >
> >
> > > Does anyone know the approximate amount of time available for user
> > > assembler programs which "add on" to the existing 1 kHz HB interrupt?
> > >
> > > Another way of stating that is...how much time is used by the 1kHz HB • ISR
> > code?
> > >
> > > --greg
> > >
> > > *****************************************************************
> > > * Greg Starr, Professor *
> > > * Department of Mechanical Engineering ph (505) 277-6298 *
> > > * University of New Mexico, Albuquerque NM 87131 FAX 277-1571 *
> > > * email- starr@unm.edu WWW- http://www.me.unm.edu/~starr/ *
> > > *****************************************************************
> > >
> > >
>
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