ARM Technical Support Knowledge Articles

CONVERTING PORT.BIT CODE FROM IAR

Applies to: C51 C Compiler

Answer


Information in this article applies to:


QUESTION

The IAR C Compiler supports a construct PORT.BIT that lets me set, clear, or test a bit of an SFR port as follows:

P2.3 = 1;       /* Set Bit */
P2.3 = 0;       /* Clear Bit */

if (P2.3 == 1)  /* Test Bit */
  {
  }

Is there a way to do this with the Keil C compiler?

ANSWER

Yes. However, the Keil compiler doesn't support the dot ('.') method of accessing bits within an SFR.

In the Keil compiler, you declare the SFRs and bits as variables and access them that way. For example:

sfr P1 = 0x90;     /* Declare an SFR for Port 1 */
sbit P1_1 = P1^1;  /* Declare a BIT for P1.1 */

void func (void)
{
P1_1 = 0;       /* Clear Bit */
P1_1 = 1;       /* Set Bit */

if (P1_1 == 1)  /* Test Bit */
  {
  }
}

Article last edited on: 2000-09-12 00:00:00

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