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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| REMOTE CONTROL Wıth a pic MCU |
 Posted: Sat Dec 31, 2022 7:44 pm |
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Guess I have a snake robot that is composed of seven links, six motors.
I want to remote control each of the motors separately. How many ways do I can make it? What is the easiest and cheapest way to apply it? |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Sat Dec 31, 2022 10:00 pm |
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Probably the cheapest would be to use 6 Hobby RC servos for the 'joints'. Then any 18 pin PIC would control them (1 pin per servo), 2 or 3 for some sort of 'remote control' interface to a 'master' computer, aka a PC ??That leaves 2 for ICSP, and a few for LEDs or heat/light sensors. Each body 'segment' would contain batteries for one servo, the 'head' segment containing the PIC and it's power supply.
The actual 'slithering' motion is fairly easy to code. You'll also need to have to decide on the 'remote control' interface as well as the 'master' command code. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19540
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| Posted: Sun Jan 01, 2023 11:52 pm |
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RC servos represent the best small motors and gearboxes you can get
for anything near the price. Buy slightly more expensive ones and these
will often have stronger final output gears and give better reliability
and accuracy.
Generally you can send one of these a single pulse, and the pulse width
determines where it will move to. The normal range is 1 to 2mSec to cover
the full range of movement. The pulse is normally repeated at an interval
to maintain position. The old traditional RC systems used 25Hz, and modern
systems go up to 400Hz. In a basic PIC system, the key is that you can
use just a single CCP, send a pulse for the first servo, then send a pulse
to the second, third, fourth etc., and then go back and start with the
first again. Use a CCP interrupt to control all this.
The control code then just has to work out the numbers to send for the
movements required, and change the values being fed to the CCP code
controlling the positions.
Though they are Chinese, Dilwe do some of the best small servos around.
Buy a couple, and have a play with driving these. They are simple to
control and work very well. |
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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| Timer1 50Hz 2ms signal |
| Posted: Thu Jan 12, 2023 1:35 pm |
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| Code: | #include <trial.h>
#fuses XT,NOWDT,NOPROTECT,NOBROWNOUT,NOLVP,NOPUT,NOWRT,NODEBUG,NOCPD
#use fast_io(b)
int i=0;
#int_timer1
void timer1_kesme()
{
set_timer1(65036);
i++;
if(i==1)
{
output_high(pin_b0);
}
if(i==2){
output_low(pin_b0);
}
if(i==10)
{i=0;}
//! if(i==20){
//!
//! output_low(pin_b0);
//! i=0;
//! }
}
void main()
{
setup_psp(PSP_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_CCP1(CCP_OFF);
setup_CCP2(CCP_OFF);
set_tris_b(0x00);
output_b(0x00);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_4);
set_timer1(65036);
enable_interrupts(int_timer1);
enable_interrupts(GLOBAL);
while(1);
} |
I tried to control sg90 servo motor using timer1, but did not work.I used different battery supply for motor.It requires 50Hz 1-2ms pulse.If I have not done any mistake, I approximately have these values.Any help? |
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gaugeguy
Joined: 05 Apr 2011
Posts: 303
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| Posted: Thu Jan 12, 2023 2:14 pm |
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| What crystal are you using? You are currently setting timer 1 to interrupt every 2000 instruction cycles. |
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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| Posted: Thu Jan 12, 2023 2:40 pm |
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| gaugeguy wrote: | | What crystal are you using? You are currently setting timer 1 to interrupt every 2000 instruction cycles. |
4MHz |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Thu Jan 12, 2023 3:04 pm |
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Which PIC ??
the file 'trial.h' probably contains this vital information and really for us to help we need to know what 'trial.h' contains.
I suspect it's 2 or 3 lines of code and should be listed in 'main()' and not in an 'included' file.
Typically a PIC like say the 16F84, a 4MHz xtal will result in 1 line of code being execute every us. |
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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| Posted: Thu Jan 12, 2023 3:10 pm |
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| temtronic wrote: | Which PIC ??
the file 'trial.h' probably contains this vital information and really for us to help we need to know what 'trial.h' contains.
I suspect it's 2 or 3 lines of code and should be listed in 'main()' and not in an 'included' file.
Typically a PIC like say the 16F84, a 4MHz xtal will result in 1 line of code being execute every us. |
| Code: | #include <16F877A.h>
#device ADC=16
#FUSES NOWDT //No Watch Dog Timer
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#use delay(crystal=4MHz)
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Sorry for that |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Thu Jan 12, 2023 3:59 pm |
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hmm...
2nd line of your header...
#device adc=16
The 877A only has a 10 bit ADC, not 16 bit ADC.
It does do the 1us per instruction though for a 4MHz clock(except for jumps and gotos of course....
You really should put those 4 lines into your program, otherwise you and others have to guess what clock speed you're running, though 'XT' is a clue to 4MHz or less...still doesn't SAY what the speed is. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Jan 12, 2023 7:35 pm |
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| The CCS IDE creates those two files. It has done this like forever. |
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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| Posted: Fri Jan 13, 2023 6:17 am |
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| temtronic wrote: | hmm...
2nd line of your header...
#device adc=16
The 877A only has a 10 bit ADC, not 16 bit ADC.
It does do the 1us per instruction though for a 4MHz clock(except for jumps and gotos of course....
You really should put those 4 lines into your program, otherwise you and others have to guess what clock speed you're running, though 'XT' is a clue to 4MHz or less...still doesn't SAY what the speed is. |
| Code: | #include <trial.h>
#device ADC=10
#fuses XT,NOWDT,NOPROTECT,NOBROWNOUT,NOLVP,NOPUT,NOWRT,NODEBUG,NOCPD
#use delay(crystal=4MHz)
#use fast_io(b)
int i=0;
#int_timer1
void timer1_kesme()
{
set_timer1(65036);
i++;
if(i==1)
{
output_high(pin_b0);
}
if(i==2){
output_low(pin_b0);
}
if(i==10)
{i=0;}
}
void main()
{
setup_psp(PSP_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_CCP1(CCP_OFF);
setup_CCP2(CCP_OFF);
set_tris_b(0x00);
output_b(0x00);
setup_timer_1(T1_INTERNAL | T1_DIV_BY_4);
set_timer1(65036);
enable_interrupts(int_timer1);
enable_interrupts(GLOBAL);
while(1);
}
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I completely cleaned all lines except pic name in header file, and wrote them onto program.Now I tried again and motor does not move. |
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gaugeguy
Joined: 05 Apr 2011
Posts: 303
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| Posted: Fri Jan 13, 2023 6:56 am |
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| Have you verified the signal coming out with a scope? Do you know your chip is running? |
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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| Posted: Fri Jan 13, 2023 7:45 am |
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| gaugeguy wrote: | | Have you verified the signal coming out with a scope? Do you know your chip is running? |
Unfortunately, I do not have any scope for tracking the signal, but I know it is running. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19540
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| Posted: Fri Jan 13, 2023 8:07 am |
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As posted, the code will send a 2mSec pulse. Now this is the maximum,
so the servo will stay right at one end of it's travel. It'll only move if
it has been set to a different position before this.
Also obvious things. The ground of the servo supply needs to connect to
the PIC ground. |
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Khansokhua
Joined: 06 Nov 2021
Posts: 92
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| Posted: Fri Jan 13, 2023 11:24 am |
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| Ttelmah wrote: | As posted, the code will send a 2mSec pulse. Now this is the maximum,
so the servo will stay right at one end of it's travel. It'll only move if
it has been set to a different position before this.
Also obvious things. The ground of the servo supply needs to connect to
the PIC ground. |
So, thank you. Now it works but it is not reliable at all. Sometimes even do not run. I tried to send just one pulse did not work. How can I reach more smooth and more accurate control using this motor? |
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