R (ohms you need) = V (volts, 3.5V) / I (35mA)
R = 100 ohms...

->Yes, I already know that. The led is a 2V, 35 mA so with 5V it will need a current limiter of 5-2 / 0.035 Ohms.

But that'll allow up to 35mA per PIC pin, over the limit...but you're driving the LED from 2 pins (unless I misunderstood).

->No, only from one pin (thus max 25 mA, according to Microchip DS).

So, R = 200 ohm across each PIC pin will give you 17.5mA from each pin, paralleled to the LED.

But I gotta tell you, it'll work, but it's not 'the way to do it'. The right way to do it is to add an external transistor or MOSFET to turn the LED on or off.

->Yes, this too I inderstand, that's the way I switch my IR leds (TSAL6100 that can eat up to 1A if used with pulsed current) from 9V source.
In this case I should not use a led that needs so much current as I drive it with an IC pin.
I used to order 5v Chicago red that need 10mA (from) MOUSER but as the shipping costs are too high, I order leds form FUTURLEC but these need 35mA and to keep my PCB simple I wish not to add an extra transistor. I guess I don't have the choice but to order the right led maybe from FARNELL if they have them... or use a transistor.

By the way, I read some info about BJT and MOSFET and still don't know what I should use in my design. MOSFETS are a little more expensive. I need to use a limiter transistor from IC pin to transistor base if I use BJT and choose the right value according to the Load switched by the transistor. I don't need to use such resistor with a mosfet (I think).
As I need to output a 40KHz PWM I could use both BJT and MOSFET even though MOSFET can swich faster but I found some IRL... mosfet wich are level-logic and can switch up to 16A and cost only .60usd versus .22usd for a BC182L for example. I just wonder if I could use such MOSFET to switch a motor or a nichrome wire instead of a bulky DIL transistor that needs a BJT, a resistor a diode,...


Or you could just increase the resistor value and use one pin... Like you said, the LED will be dimmer.

-> Right, as I don't need full brightness, I guess I will rather do that.
Skimask, thank you for your information.