LPC55S69 Traffic Light using SCT

[jalal-san]

Hello everyone, 

I am trying to create a traffic light system using SCT using the LPC55S69 Evaluation Board.

The board uses a single RBG LED which can lights up red, green and blue led at a time.

Last time, i posted a topic about problem blinking the Blue LED in "LPC55S69 Blinky Match using SCT" topic. This time, the problem that I encounter is that when I set the LED to RED, the LED did not blink when using SCT.

First of all, in the datasheet, I noticed that the BLUE LED has a function that contains SCT_OUT0. I guess that is why the port is able to use the SCT. However, the RED LED does not have any SCT output function and instead only has input SCT function called SCT_GPI3.

Even though both the RED and BLUE is the same LED, I cannot control the RED LED using the SCT.

Is there any solution/way for me to control the RED LED as well using the SCT output.

I plan to use the blinky match SCT operation to make a traffic light, so that the BLUE,RED,GREEN LED will light up at an interval of 1 second each.

Can I somehow set the SCT_GPI3 to be able to be controlled by the SCT_OUT0 ?

Below is my sample code to try to blink the RED LED using SCT.

Thank you

[jalal-san]

Alright I understand. Thank you for your explanation.

So there is no way for me to make the GPIO_6 blinking like the GPIO_4 using SCT right ? Only output pins with SCT_OUTx can be controlled as PWM output pin.

Thank you again for your assistance !

[xiangjun_rong]

Hi, Jalal

Yes, you are right, you can not configure the SCT0_GPIx pin as PWM output pin, if you want to output PWM signal, you have to select SCT0_OUTx pin. For the P1_6 pin, which can multiplex with SCT0_GPI3, you can NOT use the pin to output SCT0 PWM signal, because it is an input pin for SCT0 module.

BR

Xiangjun Rong

[xiangjun_rong · Accepted solution]

Hi,

As you can the schematic of LPC55S69-EVK board,

the LEDR is connected to P1_4, which can  function as SCT0_OUT4

the LEDG is connected to P1_7, which can function as SCT0_GPI4

the LEDB is connected to P1_6, which can function as SCT0_GPI3

As you know that the SCT0_GPIx is an input pin for SCT0 module, which can function as the SCT clock or capture pin, in any way, the SCT0_GPIx pin can not function as a SCT output pin.

You have to select another SCT0_OUTx pin as PWM output pin.

Hope it can help you

BR

XiangJun Rong