setting values and percentages

[Scampy]

maybe malcom could refresh us on the issue , but as I understand it
1.the external pwm chip has 4096 steps
2.the loop update time is in 1 sec intervals
3. the desired fade in /out period divided by the loop time yields too few "pwm" steps for a smooth looking transition if you simply divide 4096 by the number of available steps

my theory is that if the steps are chosen well the effect may be smoother

Close

With a friends help I've implemented a routine using the internal timers to get timings under a second.

ASM
INT_LIST  macro   ;  IntSource,   Label,        Type, ResetFlag?
        INT_Handler   TMR1_INT,  _ToggleLED1,   ASM,  yes        
    endm
    INT_CREATE                                  ; Creates the interrupt processor
ENDASM

T1CON = %00000001                               ; free-running, 1:1 prescaler
TMR1H = %11111111
TMR1L = %11111011
@   INT_ENABLE   TMR1_INT                       ; enable Timer1 interrupts

And

ToggleLED1:
TMR1H = %11111111
TMR1L = %11111011
pcaPwmValue0=pcaPwmValue0+1 
pcaPwmValue1=pcaPwmValue1+1 
@ INT_RETURN

I can go from 0 - 4095 in less than two minutes, which helps in test runs.

The ramp up is controlled by the case statement

case DAWN
lcdout $FE,$80+15,"DAWN "  
if pcaPwmValue0 => blue_delay_in then 
B_PWM=B_PWM+1
pcaPwmValue0 = 0 
endif
if B_PWM => B_MAX then   
Blue_Day_Cycle = DAY
endif

The value for the pulse width is then written to the PCA chip in the main loop

pcaChannel = 0                                              ;Set a PWM channel
lcdout $FE,$80,"CH1"
i2cControl = $6 + 4*pcaChannel                              ;LED0_ON_L $6
I2CWRITE SDApin,SCLpin,i2cWriteAddress,i2cControl,[0,0,0,B_PWM ]

I have everything working fine, when using pre-set values for the fade in times and brightness and can do a full dawn, day, dusk, night cycle in five minutes, I just need to be able to sort out the manual settings for adjusting the the brightness so I can enter 0-100% rather than 0 - 4095 on the LCD

Hope this additional information helps

[HenrikOlsson]

How about

PWMValue = Percentage */ 10483

?

[Scampy]

Bit of a fudge, but it works well enough

'*******************************************************************************
' Set Brightness levels for each channel


brightness:

B_max = (4095/100)*maxbright

Lcdout $FE,2
LCDOUT $FE,$80,"Set Max Brightness"
IF H_butt = 0 THEN GOSUB up
IF M_butt = 0 THEN GOSUB down

If maxbright  = 100 then
LCDOUT $FE,$C0,"Channel 1 "
LCDOut $FE,$D4,#maxbright,"%"
endif

If maxbright  =0 or maxbright <10 then
LCDOUT$FE,$C0,"Channel 1 "
LCDOut $FE,$D4,dec1 maxbright,"% "
endif

if maxbright >=10 and maxbright <100 then
LCDOUT$FE,$C0,"Channel 1 "
LCDOut $FE,$D4,dec2 maxbright,"%   "
endif
     
If S_butt = 0 then
    pause 100 
    goto brightness2
endif 
goto brightness



brightness2: 
 
W_max = (4095/100)*maxbright

Lcdout $FE,2
LCDOUT $FE,$80,"Set Max Brightness"
IF H_butt = 0 THEN GOSUB up
IF M_butt = 0 THEN GOSUB down

If maxbright  = 100 then
LCDOUT $FE,$C0,"Channel 2 "
LCDOut $FE,$D4,#maxbright,"%"
endif

If maxbright  =0 or maxbright <10 then
LCDOUT$FE,$C0,"Channel 2 "
LCDOut $FE,$D4,dec1 maxbright,"% "
endif

if maxbright >=10 and maxbright <100 then
LCDOUT$FE,$C0,"Channel 2 "
LCDOut $FE,$D4,dec2 maxbright,"%   "
endif

pause 200
If S_butt = 0 then
    pause 100 
    LCDOUT $FE,1   
    goto mainmenu
endif
goto brightness2

up:
    maxbright = maxbright + 1
    IF maxbright >= 100 THEN maxbright = 100
    pause 250
RETURN
down:
    maxbright = maxbright - 1
    IF maxbright <= 0 THEN maxbright = 0
    pause 250
RETURN

Again, the lack of floating point maths in PBP means the calculations are not exact, but this way every 1% increment equals a block of 41 steps on the PCA chip, so 50% brightness = 2050 but that's close enough to the 2047 is should be and to be honest I doubt if the human eye could distinguish the difference

[HenrikOlsson]

Hi,
If it works it works.
If you want it a little better PWMValue = Percentage */ 10483 will give you 2047 at 50%.

/Henrik.

[Scampy]

So using my variables B_max = (4095/100)*maxbright would that be

B_max = maxbright */10483

Nope - that don't work

[HenrikOlsson]

If B_Max is the value you send to the PWM controller (0-4095) and maxbright is the percentage value (0-100) as entered by the user then yes.
Actually, at 100% it'll give you 4094 so make that B_max = maxbright */10484 instead.

/Henrik.

[Scampy]

If B_Max is the value you send to the PWM controller (0-4095) and maxbright is the percentage value (0-100) as entered by the user then yes.
Actually, at 100% it'll give you 4094 so make that B_max = maxbright */10484 instead.

/Henrik.

Yes - B_max and W_max are the values that are sent to the PCA chip (0 - 4095). And maxbright has a value between 0 and 100 as you assumed. But using that line of code the values for B_max and W_max do not change from the pre-programmed default of 4095 after the menu option is used to change the max brightness level