Introduction
1483
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
64-Bit Timer Plus
After a hardware reset, the watchdog timer is disabled; however, reads or writes to the watchdog timer
registers are allowed. Once the WDEN bit is set (enabling the watchdog timer) and A5C6h is written to the
WDKEY bits, the watchdog timer enters the Pre-active state. In the Pre-active state:
•
A write to WDTCR is allowed only when the write comes with the correct key (A5C6h or DA7Eh) to the
WDKEY bits.
•
A write of DA7Eh to the WDKEY bits when the WDEN bit is set to 1 resets the counters and activates
the watchdog timer.
The watchdog timer must be configured before the watchdog timer enters the Active state. The WDEN bit
must be set to 1 before writing DA7Eh to the WDKEY bits in the Pre-active state. Every time the watchdog
timer is serviced by the correct WDKEY sequence, the watchdog timer counter is automatically reset.
30.1.6.4 Watchdog Timer Register Write Protection
Once the watchdog timer enters the Pre-active state (see
), writes to TIM12, TIM34, PRD12,
PRD34, and WDTCR are write protected (except for the WDKEY field). While the watchdog timer is in the
Timeout state, writing to the WDEN bit has no effect.
Once the watchdog timer enters its Initial state (see
), do not write to TGCR.
30.1.6.5 Watchdog Timer Power Management
The watchdog timer cannot be placed in power-down mode.
30.1.7 Reset Considerations
The timer has two reset sources: hardware reset and the timer reset (TIM12RS and TIM34RS) bits in the
timer global control register (TGCR).
30.1.7.1 Software Reset Considerations
When the TIM12RS bit in TGCR is cleared to 0, the TIM12 register is held with the current value.
When the TIM34RS bit in TGCR is cleared to 0, the TIM34 register is held with the current value.
30.1.7.2 Hardware Reset Considerations
When a hardware reset is asserted, all timer registers are set to their default values.
30.1.8 Interrupt Support
Each of the timers can send either one of two separate interrupt events (TINT
n
) to the CPU, depending on
the operating mode of the timer. The timer interrupts are generated when the count value in the counter
register reaches the value specified in the period register.
When the PLUSEN bit in the timer global control register (TGCR) is set, matches between TIM12 and
CMP
n
in dual 32-bit unchained mode will also generate interrupts. Setting the PLUSEN bit also enables
additional features for control, status, and generation of interrupts. See
for more
information.
30.1.9 DMA Event Support
Each of the timers can send either one of two separate timer events (TEVT
n
) to the DMA engine,
depending on the operating mode of the timer. The timer events are generated when the count value in
the counters register reaches the value specified in the period register.
When the PLUSEN bit in the timer global control register (TGCR) is set, matches between TIM12 and
CMP
n
in dual 32-bit unchained mode will also generate DMA events. Setting the PLUSEN bit also enables
additional features for control, status, and generation of dma events are enabled. See
for
more information.