Arm Enterprises IM-AD1

Reference Design Example

4.2.2 Oscillator lock register

The lock register is used to control access to the oscillator registers, allowing them to

be locked and unlocked. This mechanism prevents the oscillator registers from being

overwritten accidently. Table4-6 describes the lock register bits.

4.2.3 User LEDs control register

The LEDs register is a 9-bit register used to control the nine user LEDs on the logic

module. Writing a 0 to a bit lights the associated LED.

4.2.4 Push button interrupt register

The push button interrupt register contains 1 bit. It is a latched indication that the push

button on the logic module has been pressed. The output from this register is used to

drive an input to the interrupt controller. Table4-7 describes the operation of this

Table4-6 LM_LOCK register

Bits Name Access Function

16 LOCKED Read This bit indicates if the oscillator registers are

locked or unlocked:

0 = unlocked

1 = locked.

15:0 LOCKVAL Read/write Write the value

0x0000A05F

to this register to

enable write accesses to the oscillator

registers.

Write any other value to this register to lock

the oscillator registers.

Table4-7 LM_INT register

Bits Name Access Function

0 LM_INT Read This bit when SET is a latched indication that

the push button has been pressed.

Write Write 0 to this register to CLEAR the latched

indication.

Writing 1 to this register has the same effect as

pressing the push button.