8051F312 microcontroller

Question

I have the 8051F312 microcontroller, and I have to turn on the led (on the 7.bit of the P2 port). My code is not working, maybe you have some ideas.

 #include < C8051F310.H >
 #include < stdio.h >

sbit LED_16 = P2^7; // P2^7-->green LED: 1 = ON; 0 = OFF
void init(void)
    {

    // XBRN registers_init
      XBR1    = 0x40;                  // Enable the crossbar
      PCA0MD  &= 0X40;                 // Disable Watchdog  
      P2MDOUT |= 0xF0;
      ADC0CN  = 0x80;   
      ADC0CF  = 0xFC;   
      REF0CN  = 0x08;
    }

void main(void)
{
  init();

  while (1)
  {

    LED_16 = 1;                       // LED continuously illuminated

  }
}

(sorry for the format, but I had problem with the text editor)

Answer 1

First you need to set input/output to the GPIO. For 8051 micro controller family(According to my knowledge)(I don't know about 8051F312), assigning 1 to a pin sets that gpio as input and assigning 0 sets that gpio as output. So in your case first you need to set P2.7 as output. For that you need to do LED_16 = 0; in your init function. After that you need to consider how your LED is connected to your micro controller pin. If anode of LED connected to micro controller pin you need to make it HIGH to glow the LED. If cathode of LED connected to micro controller pin you need to make it LOW to glow the LED. If anode of led connected to micro controller your code should be

void main(void)
{
  init();

  while (1)
  {

    LED_16 = 1;                       // LED continuously illuminated

  }
}

If cathode of led connected to micro controller, then your code should be

void main(void)
{
  init();

  while (1)
  {

    LED_16 = 0;                       // LED continuously illuminated

  }
}

Answer 2

Please find AN101 application note from Silicon Labs. I have compared example source code with your code and I have noticed that:

1. They use XBR2 = 0x40 for crossbar initialization.
2. They enable /SYSCLK by XBR1 = 0x80.
3. They configure output pin to push-pull mode by PRT1CF |= 0x40 (I think it should be PRT1CF |= 0x80 in your case).