Hi, I am trying to get to grips with the Keil C compiler. I understand that not all SFR's are bit addressable, if not evenly divisible by 0 or 8 - a pain if you ask me! - you can tell i am new to this ;) I grabbed this code from the forum for reading bits from SFR's, which i follow ok: unsigned char mask_table[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 }; //bit_n = ( byte & mask_table[ n ] ) != 0x00; Can someone assist me in writing something similar (easy to use) for writing to a specified bit in a non bit addressable SFR - as I am struggling to come up with something that works... Thanks Barry
You could do the following: Set bit n: sfr |= mask_table[n]; Clear bit n: sfr &= ~mask_table[n]; Stefan
Or with 0 <= n <= 7 /* Set bit n: */ sfr |= (1<<n); /* Clear bit n: */ sfr &= ~(1<<n); That doesn't require mask_table[] cu, Walter Ochs