Tx/Rx leds

Hello.

I'm designing my custom-duino with rs485 communication. I have two leds directly connected to pin0 an pin1with 1k resistors to see serial activity.
My question is... do I need transistors to drive leds like shown in this schematic?

www.linksprite.com/upload/file/1294500698.pdf

Thank you very much.

No. With 1K, there is only ~3mA load on the driving pin.

I would suspect the LEDs would be very dim without the transistor drivers.

Depends on the LED. 15mcd will not be bright, while a 10,000mcd LED will be very bright, even at just 3mA.

This may be helpful:

Thank you very much