DAC pin for analogWrite? (led strip PWM, running out of pins)

[lucasparis]

Hi,

I'm running out of pins on my current design and was wondering if it's possible to use pin 26 on a teensy LC (the DAC pin) to dim an led strip through a n-chanel mosfet? (IRLB8721)

Can I do analogWrite(26, value)?

[MichaelMeissner]

Hi,

I'm running out of pins on my current design and was wondering if it's possible to use pin 26 on a teensy LC (the DAC pin) to dim an led strip through a n-chanel mosfet? (IRLB8721)

Can I do analogWrite(26, value)?

Unlike the other pins, analogWrite to the DAC pin (26 on the LC) does NOT do a pwm output (i.e. turning the pin on/off rapidly to get the appearance of dimming a LED strip.

Instead it does a true analog write, and varies the voltage from 0 to <n> volts (<n> is usually 3.3v). This is useful for producing sounds through a mono speaker with amplification. You also can't do a normal digitalWrite to the pin.

[Pazi]

Hi,

I'm running out of pins on my current design and was wondering if it's possible to use pin 26 on a teensy LC (the DAC pin) to dim an led strip through a n-chanel mosfet? (IRLB8721)

Can I do analogWrite(26, value)?

Yes. See: https://www.pjrc.com/teensy/teensyLC.html

Also, DAC analogWrite sample on page: https://www.pjrc.com/teensy/teensy31.html

But the 3.1/3.2 pin for DAC is A14, when for LC it is A12 (which is a #define for pin 26).

Ah, read Michaels message. The DAC is true analog indeed, with a single directly connected LED it wouldn't be a problem, but with a FET or some other driver it might. Still, nothing should broke if you'll just try if it works. The FET may get hot, though.