Scale Controller Resolution

MIOS programming (Assembler)
1

Hello,

i’ve got the following question:

What is the best solution to scale the controller resolution from 0-127 to 0-100?

I think this should be no problem. ??

Greetings,

Stefan

2

Hi Stefan,

here an excerpt from the midibox64 application:

;; --------------------------------------------------------------------------
;;  This function scales a 7bit value depending on a min and max value
;;  If the min value is greater than the max value, they will be
;;  automatically converted to realise a reversed scaling
;;  Input:
;;    o 7bit value in WREG
;;    o min value in MB64_POT_MIN_VALUE
;;    o max value in MB64_POT_MAX_VALUE
;;  Output:
;;    o scaled value in WREG and MIOS_PARAMETER1
;;  USES: MIOS_PARAMETER1 and MIOS_PARAMETER2
;; --------------------------------------------------------------------------
MB64_POT_ScaleValue
;; save pot value in MIOS_PARAMETER1
movwf	MIOS_PARAMETER1

SET_BSR	MB64_BASE

;; send min value if min == max
movf	MB64_POT_MIN_VALUE, W, BANKED
IFNEQ	MB64_POT_MAX_VALUE, BANKED, rgoto MB64_POT_ScaleValueDo
movwf	MIOS_PARAMETER1
rgoto	MB64_POT_ScaleValue_End

MB64_POT_ScaleValueDo
;; set MIOS_PARAMETER2[0] if min > max
bcf	MIOS_PARAMETER2, 0
movf	MB64_POT_MAX_VALUE, W, BANKED
IFLEQ	MB64_POT_MIN_VALUE, BANKED, rgoto MB64_POT_ScaleValue_NoConv
bsf	MIOS_PARAMETER2, 0
MB64_POT_ScaleValue_NoConv

;; scaled value-1 = ((current value+1) * (max-min+1)) / 128
;; swap max/min if MIOS_PARAMETER2[0] set

;; multiply current value * (max-min+1)
IFSET	MIOS_PARAMETER2, 0, rgoto MB64_POT_ScaleValue_Inv
MB64_POT_ScaleValue_NoInv
movf	MB64_POT_MIN_VALUE, W, BANKED
subwf	MB64_POT_MAX_VALUE, W, BANKED
rgoto	MB64_POT_ScaleValue_Cont1
MB64_POT_ScaleValue_Inv
movf	MB64_POT_MAX_VALUE, W, BANKED
subwf	MB64_POT_MIN_VALUE, W, BANKED
;; rgoto	MB64_POT_ScaleValue_Cont1
MB64_POT_ScaleValue_Cont1
addlw	1
mulwf	MIOS_PARAMETER1, ACCESS	; multiply with current value
;; divide result by 128 (result >> 7)
;; good trick: just shift the upper bit of the low byte into the high byte
rlf	PRODL, W
rlf	PRODH, W
andlw	0x7f
;; add min or max value depending on MIOS_PARAMETER2[0]
btfss	MIOS_PARAMETER2, 0
addwf	MB64_POT_MIN_VALUE, W, BANKED
btfsc	MIOS_PARAMETER2, 0
addwf	MB64_POT_MAX_VALUE, W, BANKED
;; store result in MIOS_PARAMETER1
movwf	MIOS_PARAMETER1
MB64_POT_ScaleValue_End
movf	MIOS_PARAMETER1, W

;; return immediately if inversion bit not set
IFCLR	MIOS_PARAMETER2, 0, return

;; else inverse the result
subwf	MB64_POT_MIN_VALUE, W, BANKED
addwf	MB64_POT_MAX_VALUE, W, BANKED
movwf	MIOS_PARAMETER1
return
[/code]









Note: MB64\_BASE is the base pointer to the page where MB64\_POT\_MIN\_VALUE and MB64\_POT\_MAX\_VALUE are located.







Best Regards, Thorsten.
3

Hi,

great news! Thank you!  ;D I tested it with an encoder. Worked very well.

Next step are motorfaders.

Cheers,

Stefan

4

Hello again,

i’ve tested it with my motorfaders. If i move a fader it works as expected.

But when i send a controller-message the fader jumps to the non scaled

position (values 0..127). I use the Midibox64e application.

I think, i have to modify “MB64E_FADER_Move” from “mb64e_fader.inc” ?

The values, which are send to the midibox, range from 0..100.

Regards,

Stefan 

5

Hi Stefan,

yes, you have to scale back the value from 0-100 to 0-127

Best Regards, Thorsten.