So we wrote this program in class that's supposed to turn one of the LEDs on the LPC1768 on/off using the buttons on the TestBed. My question is in regards to how the bits in the FIOPIN register change when the buttons are pressed. This is the program:
LPC_PINCON->PINSEL3 = LPC_PINCON->PINSEL3 & 0xFFFFFCF; //setting LED as GPIO LPC_GPIO1->FIODIR = LPC_GPIO1->FIODIR |(1<<18); //setting LED as output LPC_GPIO1->FIOSET = LPC_GPIO1->FIOSET| (1<<18); //Turning LED on(This line may be redundant at this position) //the buttons BTN1 and BTN2 are by default set to input while(1){ if ((((LPC_GPIO0->FIOPIN)>>16)&0x1)==0){ wait(200); //debounce LPC_GPIO1->FIOSET |= (1<<LED0); } else if(!(((LPC_GPIO0->FIOPIN)>>6)&0x1)){ wait(200); //debounce LPC_GPIO1->FIOCLR |= (1<<LED0); }
Based on my understanding of how the buttons work, this is how I assume the program will run: PS: BTN1 is at P0.6 and BTN2 is at P0.16 1. When the program starts(before any buttons are pressed) FIOPIN bits 6 and 16 are both 0. So the LED is on. 2. Assume we press BTN2. Then FIOPIN bit 6 is 0, and bit 16 is 1, so LED turns off. 3. Now press BTN1. Bit 6 is now 1 and bit 16 is still 1. LED is still off. 4. Press BTN2. Bit 6 is still 1, but bit 16 is now 0. LED will turn on.
Is this correct? PS: I don't have access to the microcontroller at home, that's why I'm assuming and simulating what would/might happen if so and so.
My assumption is that the buttons aren't press and hold buttons, i.e. when you press a button it's state(1/0) gets changed in the FIOPIN register till it gets pressed again.