Question about connexion of LED on the OlinuxMicro board

[flavigny]

Hello,

the LED1 is not documented in the user manual.
I am rather timorous about hardware.


Anyone could confirm how to connect a LED.

I imagine two ways for a "direct" connection:
1) insert the LED  between a GPIO pin and ground (so the current is coming from iMx233, limited by internal resistor of 47 kO)
2) insert the LED between + (3.3V) and the Gpio pin (so the current is absorbed by iMX233 without internal resistor).
Is it mandatory, (or cautious) to add a resistor?  (how many Ohms ?).

Regards
PO.

[Kean]

Looking at the schematic of Micro board, LED1 anode is connected to the GPIO, and its cathode connects to GND via a 2k2 resistor.  So the GPIO is sourcing current.  Different resistors can be used based on the Vf of the LED you use and brightness required, but I'd always recommend including one (100R or greater) and not relying on any GPIO current limiting.

Kean

[Fadil Berisha]

Hello,

the LED1 is not documented in the user manual.

You are right, LED1 is listed on page 36 with no description.
This is system LED. Light is solid ON or blinking when kernel take control of system. 

Anyone could confirm how to connect a LED.

Led is already connected, please refer to Kean's  answer. 

Fadil Berisha 

[flavigny]

Looking at the schematic of Micro board, LED1 anode is connected to the GPIO, and its cathode connects to GND via a 2k2 resistor.  So the GPIO is sourcing current.  Different resistors can be used based on the Vf of the LED you use and brightness required, but I'd always recommend including one (100R or greater) and not relying on any GPIO current limiting.

Kean

Ok, it is clear, I will try in a few days.
Regards