LPC43s37: Red LED in RGB does not blink

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LPC43s37: Red LED in RGB does not blink

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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by ramawadh on Thu Aug 06 13:38:02 MST 2015
I have recently Bought LPC43s37 development board. I just started working with it using LPCXPRESSO IDE. I am running Periph_Blinky Example. I found that Green and Blue LED blink when I change LED number 0 and 1.
But Red LED does not blink if I use LED number 2. As per code "io_port_t gpioLEDBits[] = {{3, 5}, {0, 7}, {3, 7}};" third element of this Array is Red LED.

I am not sure what might be issue.

If any one encounter same issue, please help me in resolving this issue.
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lpcware
NXP Employee
NXP Employee
Content originally posted in LPCWare by bavarian on Mon Aug 10 02:38:38 MST 2015
The third element GPIO3[7] is indeed connected to the red LED. This GPIO can be found on P6_11 on function 0, so maybe you look for this configuration to make sure that the port is correctly configured.

Regards,
NXP Support Team
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thomascurry
Contributor II

Debugged and found a hardware issue. On my lpc43s37 lpcxpresso board and found that the signals are correct to the RGB LED but the RGB LED chip mounted on the board does not have correct pin out.  Blue and Green LED light as expected as long as the RED led PIN #1 set  high.  But as soon as PIN #1 is brought low both Blue and green LED turn off.  PIN #1 should be tied to Power and Red led should be pin #2 on the RGB led chip.  This is a common pin out of RGB led chips.  http://www.kingbrightusa.com/images/catalog/SPEC/AAA3528BGRS-129-C3.pdf   The RED led pin #1 is providing the 3.3 volts to the anode of all 3 LEDs.  The schematic shows that the RGB LED is this one http://www.wenrun.com/uploads/soft/150325/11-150325150134.pdf  but the circuit behaves like the AAA3528BGRS-129-C3  is mounted on the board.   Using a multimeter showed that when all led pins are set low ( #3,#4,#1) all leds are off which should not be the case if the correct LED is installed.  Verified on another LPC43S37 the same behavior. 

Conclude that it is impossible to light the Red LED of the RGB led without a modification of the hardware. Which would be replace the RGB Led with the one specified in the schematic or re route the PCB to match the RGB led that is installed on the board.