Question

I’m trying to read certain values from a particular register. The manual specifies that I must access the 16-bit LSB access first and 16-bit MSB access next. Do I just read in all 32 bits at once and then mask the remaining 16 msb/lsb respectively as needed? Or would there be a way to read only 16 bits fist.

Thanks,
Neco

Answer 1

If the manual says to first access the 16-bit LSB and then the 16-bit MSB, do as the manual says.

For example (little endian):

#define REG (*(volatile uint32_t *) 0x1234)

uint16_t val_hi, val_lo;

val_lo = *((volatile uint16_t *) &REG);
val_hi = *((volatile uint16_t *) &REG + 1);

Note that compilers also sometimes provide HI and LO identifiers to access LSB or MSB, like in addition to REG in the example:

#define REGL (*(volatile uint16_t *) 0x1234)
#define REGH (*(volatile uint16_t *) 0x1236)