Hi Nhilar. I'm not familiar with the 12F615 but we use this simple program to control the speed of a small motor. The Hpwm output goes to the gate of an N channel FET. The drain feeds the motor. Other side of motor to B+. Maybe this will help you to get it going.

'COMPILED FOR 12F683

CMCON0 = 7 'comparators off
ANSEL = 0 'all inputs digital. adcin command will convert it to analog.
DEFINE OSCCON_1K 1 ' Set OSCCON for 1K device
@ DEVICE MCLR_OFF, INTRC_OSC_NOCLKOUT, WDT_ON, BOD_ON, PWRT_ON, PROTECT_ON
TRISIO = %00010001 'GPIO.0 GPIO.4 (ANA3) INPUTS
GPIO = 0 'ALL OUTPUTS LOW
SPEEDPOT VAR BYTE

START:
CCP1CON = 0 'TURN OFF PWM
NAP 0 'REDUCE BATTERY DRAIN
IF GPIO.0 = 1 Then VIBRATE 'has pulldown 47K resistor
GoTo START

VIBRATE:
ADCIN 3,SPEEDPOT 'USING 1M POT ACROSS SUPPLY
HPwm 1,SPEEDPOT,15000 'THIS MOTOR WORKED BEST @ 15KHZ
IF GPIO.0 = 1 Then VIBRATE
GoTo START