Architecture specific RTT functions for ESP32. More...
Detailed Description
Architecture specific RTT functions for ESP32.
The RTT peripheral driver implements a 32-bit RTT counter with a frequency of 32.768 kHz. It uses either
- the 48-bit RTC counter if an external 32.678 kHz crystal is connected or
- the 64-bit microsecond system timer.
For this purpose, a hardware abstraction layer is defined by a driver interface of the type rtt_hw_driver_t, which generally provides a 48-bit RTC counter with a frequency of 32.678 kHz. This way the RTT implementation always sees a 48-bit counter with a frequency of 32.768 kHz regardless of which hardware implementation is actually used.
If pseudomodule esp_rtc_timer_32 is enabled by the board definition and the 32.768 kHz crystal is actually connected, the 48-bit RTC counter is used. Otherwise, the 64 bit microsecond system timer is used.
Since the 64-bit microsecond system timer does not work during light/deep or during a reboot, the status of the 64-bit microsecond system timer is saved in RTC memory before entering a sleep mode or reboot. When leaving the sleep mode or after a reboot, it will be updated from the RTC counter.
Definition in file rtt_arch.h.
#include "periph/rtt.h"
Include dependency graph for rtt_arch.h:Go to the source code of this file.
Data Structures | |
| struct | rtt_hw_driver_t |
| RTT hardware abstraction layer driver. More... | |
| #define | RTT_HW_COUNTER_MAX ((1ULL << 48) - 1) |
| Maximum value of the 48-bit RTT hardware counter. | |
| uint64_t | rtt_pm_sleep_enter (unsigned mode) |
| Called before the power management enters a light or deep sleep mode. More... | |
| void | rtt_pm_sleep_exit (uint32_t cause) |
| Called after the power management left light sleep mode. More... | |
Function Documentation
◆ rtt_pm_sleep_enter()
| uint64_t rtt_pm_sleep_enter | ( | unsigned | mode | ) |
Called before the power management enters a light or deep sleep mode.
- Parameters
-
mode sleep mode that is entered
- Returns
- time to sleep in us
◆ rtt_pm_sleep_exit()
| void rtt_pm_sleep_exit | ( | uint32_t | cause | ) |
Called after the power management left light sleep mode.
- Parameters
-
cause wake-up cause
