0001 0000h
0001 0001h
0001 0002h
FFFF FFFFh
0000 0000h
0000 FFFFh
Timer interrupt and
timer event generated
Introduction
1480
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
64-Bit Timer Plus
30.1.5.4.3 Timer Capture Registers
When the timer has a timeout due to a normal expiration of timer, external input event in Event Capture
Mode, or read of timer counter registers in Read Reset Mode, the values of the timer counter registers
(TIM12 and TIM34) are copied onto the timer counter capture registers (CAP12 and CAP34). Note that the
value in TDDR is not captured when a read of TIM34 happens.
30.1.5.4.4 Counter and Period Registers Used in GP Timer Modes
summarizes how the counter registers (TIM
n
) and period registers (PRD
n
) are used in each
GP timer mode.
Table 30-5. Counter and Period Registers Used in GP Timer Modes
Timer Mode
Counter Registers
Period Registers
64-bit general-purpose
TIM34:TIM12
PRD34:PRD12
Dual 32-bit chained:
Prescaler (Timer 3:4)
TIM34
PRD34
Timer (Timer 1:2)
TIM12
PRD12
Dual 32-bit unchained:
Timer (Timer 1:2)
TIM12
PRD12
Timer with prescaler (Timer 3:4)
TDDR34 bits and TIM34
PSC34 bits and PRD34
30.1.5.5 Timer Operation Boundary Conditions
The following boundary conditions affect the timer operation.
30.1.5.5.1 Timer Counter Overflow
Timer counter overflow can happen when the timer counter register is set to a value greater than the value
in the timer period register. The counter reaches its maximum value (FFFF FFFFh or
FFFF FFFF FFFF FFFFh), rolls over to 0, and continues counting until it reaches the timer period. An
example is in
Figure 30-8. 32-Bit Timer Counter Overflow Example
30.1.5.5.2 Writing to Registers of an Active Timer
Writes to most timer registers are not allowed when the timer is active, except for setting the timer period
reload registers (REL12 and REL34) and stopping and resetting the timers. In the 64-bit and dual 32-bit
timer modes, registers that are protected by hardware are:
•
TIM12
•
TIM34
•
PRD12
•
PRD34
•
TCR (except the ENAMODE bit)
•
TGCR (except the TIM12RS and TIM34RS bits)