9.7 Timers
A large selection of timers are available as part of the CC2652PSIP device. These timers are:
•
Real-Time Clock (RTC)
A 70-bit 3-channel timer running on the 32 kHz low frequency system clock (SCLK_LF)
This timer is available in all power modes except Shutdown. The timer can be calibrated to compensate for
frequency drift when using the LF RCOSC as the low frequency system clock. If an external LF clock with
frequency different from 32.768 kHz is used, the RTC tick speed can be adjusted to compensate for this.
When using TI-RTOS, the RTC is used as the base timer in the operating system and should thus only be
accessed through the kernel APIs such as the Clock module. The real time clock can also be read by the
Sensor Controller Engine to timestamp sensor data and also has dedicated capture channels. By default, the
RTC halts when a debugger halts the device.
•
General Purpose Timers (GPTIMER)
The four flexible GPTIMERs can be used as either 4× 32 bit timers or 8× 16 bit timers, all running on up to 48
MHz. Each of the 16- or 32-bit timers support a wide range of features such as one-shot or periodic counting,
pulse width modulation (PWM), time counting between edges and edge counting. The inputs and outputs of
the timer are connected to the device event fabric, which allows the timers to interact with signals such as
GPIO inputs, other timers, DMA and ADC. The GPTIMERs are available in Active and Idle power modes.
•
Sensor Controller Timers
The Sensor Controller contains 3 timers:
AUX Timer 0 and 1 are 16-bit timers with a 2
N
prescaler. Timers can either increment on a clock or on each
edge of a selected tick source. Both one-shot and periodical timer modes are available.
AUX Timer 2 is a 16-bit timer that can operate at 24 MHz, 2 MHz or 32 kHz independent of the Sensor
Controller functionality. There are 4 capture or compare channels, which can be operated in one-shot or
periodical modes. The timer can be used to generate events for the Sensor Controller Engine or the ADC, as
well as for PWM output or waveform generation.
•
Radio Timer
A multichannel 32-bit timer running at 4 MHz is available as part of the device radio. The radio timer is
typically used as the timing base in wireless network communication using the 32-bit timing word as the
network time. The radio timer is synchronized with the RTC by using a dedicated radio API when the device
radio is turned on or off. This ensures that for a network stack, the radio timer seems to always be running
when the radio is enabled. The radio timer is in most cases used indirectly through the trigger time fields
in the radio APIs and should only be used when running the accurate 48 MHz high frequency crystal is the
source of SCLK_HF.
•
Watchdog timer
The watchdog timer is used to regain control if the system operates incorrectly due to software errors. It is
typically used to generate an interrupt to and reset of the device for the case where periodic monitoring of the
system components and tasks fails to verify proper functionality. The watchdog timer runs on a 1.5 MHz clock
rate and cannot be stopped once enabled. The watchdog timer pauses to run in Standby power mode and
when a debugger halts the device.
SWRS263A – FEBRUARY 2021 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
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