LM3S3748 Datasheet, PDF (47/753 Pages) List of Unclassifed Manufacturers – Microcontroller

LM3S3748 Microcontroller
Bit/Field
0
Name
ENABLE
Type Reset Description
R/W 0 Enable
Value Description
0 Counter disabled.
1 Counter operates in a multi-shot way. That is, counter loads with the Reload
value and then begins counting down. On reaching 0, it sets the
COUNTFLAG to 1 and optionally pends the SysTick handler, based on
TICKINT. It then loads the Reload value again, and begins counting.
SysTick Reload Value Register
Use the SysTick Reload Value Register to specify the start value to load into the current value
register when the counter reaches 0. It can be any value between 1 and 0x00FF.FFFF. A start value
of 0 is possible, but has no effect because the SysTick interrupt and COUNTFLAG are activated
when counting from 1 to 0.
Therefore, as a multi-shot timer, repeated over and over, it fires every N+1 clock pulse, where N is
any value from 1 to 0x00FF.FFFF. So, if the tick interrupt is required every 100 clock pulses, 99
must be written into the RELOAD. If a new value is written on each tick interrupt, so treated as single
shot, then the actual count down must be written. For example, if a tick is next required after 400
clock pulses, 400 must be written into the RELOAD.
Bit/Field Name Type Reset Description
31:24 reserved RO
0 Software should not rely on the value of a reserved bit. To provide compatibility with
future products, the value of a reserved bit should be preserved across a read-modify-write
operation.
23:0 RELOAD W1C - Reload
Value to load into the SysTick Current Value Register when the counter reaches 0.
SysTick Current Value Register
Use the SysTick Current Value Register to find the current value in the register.
Bit/Field Name Type Reset Description
31:24 reserved RO
0 Software should not rely on the value of a reserved bit. To provide compatibility with
future products, the value of a reserved bit should be preserved across a
read-modify-write operation.
23:0 CURRENT W1C - Current Value
Current value at the time the register is accessed. No read-modify-write protection is
provided, so change with care.
This register is write-clear. Writing to it with any value clears the register to 0. Clearing
this register also clears the COUNTFLAG bit of the SysTick Control and Status Register.
SysTick Calibration Value Register
The SysTick Calibration Value register is not implemented.
April 08, 2008
47
Preliminary