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erhane
Joined: 01 Jul 2014
Posts: 41
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| Calculation of Stepper Motor Ramp Profile (Linear or S-Ramp) |
 Posted: Tue Aug 26, 2014 2:13 am |
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Hello,
I want to create a pulse profile which should be send via an output to motor driver IC.
I have pre-calculated profile and filled to an array and when i want to start my motor i am collecting delay values from that array.
| Code: |
unsigned int const periods[117]={2449,1015,779,656,578,523,481,447,420,397,378,361,346,333,322,311,302,293,285,277,271,264,258,253,247,243,238,234,229,226,222,
218,215,212,209,206,203,200,197,195,192,190,188,186,184,182,180,178,176,174,172,171,169,167,166,164,163,162,160,159,157,156,155,154,152,151,150,149,148,147,
146,145,144,143,142,141,140,139,138,137,136,135,134,133,132,131,130,129,128,127,126,125,124,123,122,121,120,119,118,117,116,115,114,113,112,111,110,109,108,
107,106,105,104,103,102,101,100};
//delay_us values. start from 2449us and reaching maximum speed at 100us delay.
//for(i=0,i<117,i++)
//{
//output_high(pin)
//delay_us(periods[next])
//output_low(pin)
//}
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The problem is, my new system has different speed profiles which will be given by user that is why ramp profile of movement changes time to time and i should re-calculate that ramp profile every start of movement.
Do you have any algorithm to help me to calculate and fill that array?
I will have max speed delay value, distance to move(in pulse) and steps to reach max speed values.
Thank you |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Aug 26, 2014 8:07 am |
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You have not given me enough to work on.
1) How are you controlling the 'OFF' period?
2) Do you HAVE to use an array?
Mike |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Tue Aug 26, 2014 9:32 am |
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a reminder:
the largest value that can fit into a CCS unsigned int is ?????? |
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erhane
Joined: 01 Jul 2014
Posts: 41
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| Posted: Tue Aug 26, 2014 9:42 am |
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mike,
1_i am planing to create pulse via timer interrupt. 1us duration pulse is enough. i think 2us period timer will be ok.
2_i don't have to use array but the problem is i am driving my stepper motor in 256 microstepping mode and i need high speeds. My desired speed is 4us period(250khz) pulse. I have 32 MHz oscillator and this is not enough to make calculations on-fly i think? Do you have any suggestions?.
ASMBOY,
length of my array is around approximately 32000 values. Each value is between 1300-0. Do you think ROM will be problematic with this kind of huge array (int16)? |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Tue Aug 26, 2014 9:55 am |
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lets try again:
your array is UNSIGNED INT
SO.....
when reading the MANUAL for CCS C ,
what is the largest integer value that can
fit into a CCS unsigned int i?????? |
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erhane
Joined: 01 Jul 2014
Posts: 41
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| Posted: Tue Aug 26, 2014 12:04 pm |
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| Bro as you can see , i wrote int16 |
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temtronic
Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario
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| Posted: Tue Aug 26, 2014 12:42 pm |
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from the OP...
unsigned int const periods[117]={2449,1015,779,656,578,523,481,447,420,397
that ain't 16 bits !!!
jay |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Aug 26, 2014 2:58 pm |
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This is like pulling teeth.
You're working on a need to know basis and only giving us a fraction of what we need.
In the OP you describe a conventional(ish) DC motor drive, then later declare it's a stepper.
Like I said before I don't know where to start trying to help you.
So. lets have a complete picture.
Mike |
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erhane
Joined: 01 Jul 2014
Posts: 41
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| Posted: Mon Sep 01, 2014 4:28 am |
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temtronic, 16bit can save up to 32767. as you can see my largest value is 2449!? so where is the problem.
thank you
| temtronic wrote: | from the OP...
unsigned int const periods[117]={2449,1015,779,656,578,523,481,447,420,397
that ain't 16 bits !!!
jay |
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erhane
Joined: 01 Jul 2014
Posts: 41
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| Posted: Mon Sep 01, 2014 4:31 am |
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Hello Mike,
I am just trying to generate a indexer pulse to my stepper motor driver IC. I had need to code a ramp function which will calculate frequency on the fly. i found something and made some coding. i will share my results and final code here after testings.
| Mike Walne wrote: | This is like pulling teeth.
You're working on a need to know basis and only giving us a fraction of what we need.
In the OP you describe a conventional(ish) DC motor drive, then later declare it's a stepper.
Like I said before I don't know where to start trying to help you.
So. lets have a complete picture.
Mike |
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temtronic
Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario
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| Posted: Mon Sep 01, 2014 5:23 am |
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your problem is this...
"unsigned int "
For some reason you think an unsigned integer is 16 bits, which it is NOT.
Please consult the CCS C Help files (press F11 in an open project), read the 'data definitions' section.
You'll see that unsigned int is defined as an 8 bit data NOT 16.
I'm assuming that the other version of C you've worked with had defaulted to 16 bit unsigned integers. Me, I always think of micro data as 0 to 255, 8 bits as data busses I started with were all 8 bits wide, except the Moto 1 bit wide micro.
jay |
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erhane
Joined: 01 Jul 2014
Posts: 41
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| Posted: Mon Sep 01, 2014 6:16 am |
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Oh you are right, i corrected it. Thank you =)
| temtronic wrote: | your problem is this...
"unsigned int "
For some reason you think an unsigned integer is 16 bits, which it is NOT.
Please consult the CCS C Help files (press F11 in an open project), read the 'data definitions' section.
You'll see that unsigned int is defined as an 8 bit data NOT 16.
I'm assuming that the other version of C you've worked with had defaulted to 16 bit unsigned integers. Me, I always think of micro data as 0 to 255, 8 bits as data busses I started with were all 8 bits wide, except the Moto 1 bit wide micro.
jay |
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