ARM IM-AD1 - Manual (Page 57)

Reference Design Example
ARM DUI 0163B Copyright © 2001-2003. All rights reserved. 4-11
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. Table 4-6 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. Table 4-7 describes the operation of this
register.
Table 4-6 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.
Table 4-7 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.