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L6482 Speed issue

c23
Associate
Posted on April 11, 2014 at 14:47

Hi,

I'm tring to use a L6482 using only speed (Run) command because we have to use the motor in speed mode. Acc/Del are on our control. Chip Acc/Del are set to infinite (0xFFF) and MIN_SPEED/MAX_SPEED at 0,0x3FF. STEP_MODE is on 1/4 step

Everything works fine, I can read/write all registers.

If  I give a Run command (0x50) motor runs at that frequency and CurrentSpeed register give use the Run frequency (divided by 4 because I use 1/4 microstep). Real frequency of the motor is also  correct.

This is true only if  I write equal or greater speeds (i.e increase frequecy).

If I try to decrease speed the motor runs at last speed and SPEED registry remain at that value. No way to decelerate. This happen if I give the RUN command  one shot or continuosly as well.

Only if I execute a RUN( 0x00 ) the motor stop and SPEED goes at 0x00 as well.

There are particular registry setting or sequence in order to use th L6482 in a direct speed mode control?

Thanks

#l6482
3 REPLIES 3
Enrico Poli
ST Employee
Posted on April 24, 2014 at 14:39

Hi,

We are investigating you findings.

Meanwhile you could try to set the acceleration and deceleration to the maximum (0xFFE) without enabling the infinite acc\dec mode.

Regards

Enrico

c23
Associate
Posted on April 28, 2014 at 14:45

Hi,

With 0xFFE the chip behavior is correct. But because impose a fixed acc/del this impacts in our control strategy.

I attach 2 bitmaps that show the effect. Yellow line is the speed (frequency) commanded, Red one is the speed calculated as ABS_POS(t)-ABS_POS(t-1). dT=4ms.

One is with oxFFE ACC/DEC programmed in L6482 and infinite Acc/Dec commanded from us.

Second is with 0xFFFACC/DEC programmed in L6482 and some Acc/Dec commanded from us

Regards

Carlo

________________

Attachments :

L6482_0xFFE_programmed_with_infinity_acc_commanded.bmp : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006HzHc&d=%2Fa%2F0X0000000bJE%2FirQsPWpoJxAxVyo9TVZSbL5V.ProgspTIvN3cSQIG04&asPdf=false

L6482_0xFFF_programmed_with_normal_acc_commanded.bmp : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Hz3j&d=%2Fa%2F0X0000000bJC%2FQJucHgcMAb2sWCbXHahQALvVw8bpQo6VanhgS3tLBWM&asPdf=false
Enrico Poli
ST Employee
Posted on May 26, 2014 at 09:40

Hi,

In this case I think you can use the stepclock operation.

In this way you can impose an arbitrary speed profile without any limitation.

Regadrs

Enrico