I am struggling to figure out this practice problem and using an HCS12 Microcont

Question

I

am struggling to figure out this practice problem and using an HCS12 Microcontrollers and Embedded Systems, 1st Edition. Reviewing the chapters was a bit challenging to find an accurate answer. I need help to solve this practice problem and it is due today. Thank you

BRCLR Branch if Bits Cleared-This performs a logical AND on the content of a mask byte and the content of a memory location, bit by bit, then branches if and only if all bits with a value of 1 in the mask byte correspond to bits with a value of 0 in the tested byte

Data Direction Register DDRB is used to configure PORTB as either an input or output port. Clear the bits in DDRB will make PORTB an input port, set the bits in DDRA will make it an output port

this exercise relates to the HCS12 Microcontrollers and Embedded Systems but does not say what the microcontroller type. just ask what is the results after BSET    DDRB,%10000001.

Does this answer your question?

After BCLR    DDRB,%00010001

PORTB pin4 and pin0 are configured as output pins

PORTB pin4 and pin0 are configured as input pins

PORTB pin7, 6, 5, 3, 2, 1 are configured as output pins

PORTB pin7, 6, 5, 3, 2, 1 are configured as input pins

Explanation / Answer

Answer:- BSET DDRB %10000001 will make pin 7 and pin 0 of PORTB as output pin, rest pins function is same as earlier i.e no change for rest pins whether they were input or output, they will work same.

BCLR DDRB, %00010001 This will make PORTB pin 0 and pin 4 as input port. Rest pin functions are not changed whether they were input or output they will do as defined earlier.

Note:- If earlier not defined then default operation of pin will be perfomed by port pin.

so for BSET and BCLR only the bit of given address is affected for which the mask bit is set, rest bits are unaffected. The syntax for these two instruction is-

BSET MemAddr MaskBits

BCLR MemAddr MaskBits

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.