programming LEDs->
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hi again,
i'm using the max7219 and a bs2 to program 52 discrete LEDs. i've managed
to figure out how to program them into the patterns i need (thanks in part to
some of the tips people here have given me- my first foray into basic stamp
programming has been very succesful so far!), but i have one last thing that i
would like to do that i can't seem to figure out:
i'm hoping to program the LEDs to go dim to bright simultaneously, analog
style. i thought i could do this by some sort of PWM variant, but i've been told
that the stamp is not fast enough to be able to process that. i feel like there
must be a way! anyone have any tips on how to program this, or whether its
possible??
thanks
heather
i'm using the max7219 and a bs2 to program 52 discrete LEDs. i've managed
to figure out how to program them into the patterns i need (thanks in part to
some of the tips people here have given me- my first foray into basic stamp
programming has been very succesful so far!), but i have one last thing that i
would like to do that i can't seem to figure out:
i'm hoping to program the LEDs to go dim to bright simultaneously, analog
style. i thought i could do this by some sort of PWM variant, but i've been told
that the stamp is not fast enough to be able to process that. i feel like there
must be a way! anyone have any tips on how to program this, or whether its
possible??
thanks
heather
Comments
The MAX7219 has an intensity register which will allow you to adjust
the brightness of the LEDs. The data sheet says this alters an
internal PWM driver. There is also a single resistor connected to the
IC which would allow you to adjust the brightness manually. I have not
personally done this but if you have a good handle on the rest of the
programming you should have no trouble adjusting the intensity
register.
Lee Harker
--- In basicstamps@yahoogroups.com, "myamygdala" <myamygdala@y...>
wrote:
>
>
> hi again,
>
> i'm using the max7219 and a bs2 to program 52 discrete LEDs. i've
managed
> to figure out how to program them into the patterns i need (thanks
in part to
> some of the tips people here have given me- my first foray into
basic stamp
> programming has been very succesful so far!), but i have one last
thing that i
> would like to do that i can't seem to figure out:
>
> i'm hoping to program the LEDs to go dim to bright simultaneously,
analog
> style. i thought i could do this by some sort of PWM variant, but
i've been told
> that the stamp is not fast enough to be able to process that. i feel
like there
> must be a way! anyone have any tips on how to program this, or
whether its
> possible??
>
> thanks
>
> heather
> style. i thought i could do this by some sort of PWM variant, but i've been
told
> that the stamp is not fast enough to be able to process that. i feel like
there
> must be a way! anyone have any tips on how to program this, or whether its
> possible??
Actually the MAX7219 will do this for you; From the data sheet
@<http://pdfserv.maxim-ic.com/en/ds/MAX7219-MAX7221.pdf>:
"Digital control of display brightness is provided by an
internal pulse-width modulator, which is controlled by
the lower nibble of the intensity register. The modulator
scales the average segment current in 16 steps from a
maximum of 31/32 down to 1/32 of the peak current set
by RSET (15/16 to 1/16 on MAX7221)"
Basically you write an intensity value (0-15) into the intensity register
(0x0A). Done. ;-)
--
Enjoy,
George Warner,
Schizophrenic Optimization Scientists
Apple Developer Technical Support (DTS)