L6482 Speed issue

[c23]

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

[Enrico Poli]

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]

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]

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