This is no longer required since the functions automatically get
pulled in based on the usage. A quick summary of footprint
comparisions before and after these set of patches is shown below:
Hello-World: (simplified for readability)
old Total image size:~ 104902 bytes (.bin may be padded larger)
old Total image size:~ 105254 bytes (.bin may be padded larger)
Per-archive contributions to ELF file:
Archive File DRAM .data & .bss IRAM Flash code & rodata Total
old libesp32.a 1973 177 4445 3939 2267 12801
new libesp32.a 1973 185 4473 3939 2267 12837
new libnvs_flash.a 0 92 0 274 8 374
new libstdc++.a 0 0 0 24 0 24
For some reason, nvs_flash.a (~400bytes) gets pulled in (particularly
the nvs_flash_init() function).
Power-Save: (simplified for readability)
old Total image size:~ 421347 bytes (.bin may be padded larger)
old Total image size:~ 421235 bytes (.bin may be padded larger)
old libtcpip_adapter.a 0 81 0 1947 115 2143
new libtcpip_adapter.a 0 69 0 1897 115 2081
The size actually shrinks a bit, since the AP interface function
doesn't get pulled in.
Since only the used interface's start function gets called, it pulls
in only the functions that are required in the current application,
thereby saving footprint.
Restart being a lower-layer system-level function, needn't depend on
the higher level Wi-Fi libraries.
This also enables us to get rid of one more WIFI_ENABLED ifdef check
For config-only components, component.mk should now contain "COMPONENT_CONFIG_ONLY := 1"
Also refactored some of the generation of linker paths, library list. This required cleaning up the way the bootloader
project works, it's now mostly independent from the parent.
NVS is used to store PHY calibration data, WiFi configuration, and BT
configuration. Previously BT examples did not call nvs_flash_init,
relying on the fact that it is called during PHY init. However PHY init
did not handle possible NVS initialization errors.
This change moves PHY init procedure into the application, and adds
diagnostic messages to BT config management routines if NVS is not
initialized.
Currently the last 128KB of DRAM is reserved for the bootloader & early boot stacks. This means if >192KB of static DRAM
is allocated, the only available heap is this region - which is disabled until the scheduler starts. As a result, you
get either heap corruption on early boot if the static data overlaps startup heap (leading to very weird errors), or
FreeRTOS will fail to start when it can't malloc() anything.
Long term fix is to move the stacks & bootloader data to the very end of RAM, and only reserve that part for early
boot. This is a little fiddly because of also wanting to make sure this memory is not preemptively fragmented when it
gets reintroduced to the heap. This will become more important if/when we have more static allocation options in the
future.
For now, these errors make it clear why the boot has failed.
Ref TW13909
Because of errata related to BOD reset function, brownout is handled as follows:
- attach an ISR to brownout interrupt
- when ISR happens, print a message and do a software restart
- esp_restart_nonos enables RTC watchdog, so if restart fails,
there will be one more attempt to restart (using the RTC
watchdog)
RTC watchdog didn’t have any actions configured for any of the stages.
This change configures it to use SW_SYSTEM_RESET at stage 0 and a
full reset at stage 1. The timeout is now calculated based on
RTC_SLOW_CLK frequency.
Specifying -fexceptions for the compiler is not enough.
- add necessary zero padding after .eh_frame section
- link .gcc_except_table_table in a way flash script does not complain
- call __registrer_frame_info before global constructors
Kudos jcmvbkbc for the necessary help.
Implements support for system level traces compatible with SEGGER
SystemView tool on top of ESP32 application tracing module.
That kind of traces can help to analyse program's behaviour.
SystemView can show timeline of tasks/ISRs execution, context switches,
statistics related to the CPUs' load distribution etc.
Also this commit adds useful feature to ESP32 application tracing module:
- Trace data buffering is implemented to handle temporary peaks of events load
Bug occurs when core dump destination in menuconfig is set to flash. When
programme crashes, xt_unhandled_exception or panicHandler will both trigger
commonErrorHandler. commonErrorHandler calls esp_core_dump_to_flash which
will attempt to use DPORT functions and hang due to trying to a stall and already
stalled processor (already stalled in xt_unhandled_exception and panicHandler).
Program will eventually be rebooted when wdt expires.
Added esp_dport_access_int_deinit after calls to haltOtherCore() so that DPORT
functions don't try to halt and already halted cpu hence preventing hang.
Fixes TW#12944 https://github.com/espressif/esp-idf/issues/646
Small changes to clock calibration value will cause increasing errors
the longer the device runs. Consider the case of deep sleep, assuming
that RTC counter is used for timekeeping:
- before sleep:
time_before = rtc_counter * calibration_val
- after sleep:
time_after = (rtc_counter + sleep_count) * (calibration_val + epsilon)
where 'epsilon' is a small estimation error of 'calibration_val'.
The apparent sleep duration thus will be:
time_after - time_before = sleep_count * (calibration_val + epsilon)
+ rtc_counter * epsilon
Second term on the right hand side is the error in time difference
estimation, it is proportional to the total system runtime (rtc_counter).
To avoid this issue, this change makes RTC_SLOW_CLK calibration value
persistent across restarts. This allows the calibration value update to
be preformed, while keeping time after update same as before the update.
This fixes a bug introduced by !848, where APP CPU would not be reset
during esp_restart, if esp_restart was called from a task running on APP
CPU, and wouldn’t be reset by PRO CPU on startup.
This change replaces stalling APP CPU with resetting it.
Also adds a non-automated esp_restart tests.
DPORT access protection can not work when the other CPU is stalled.
Writes to DPORT registers in esp_restart caused the program to hang due
to access protection, and the reset happened due to RTC_WDT, not SW_RST.
This change adds esp_dport_access_int_deinit function and calls it from
esp_restart once the other core is stalled.
This seems to clean up some of the more wrong addr2line output results (not
sure why, something to do with optimisations I think - perhaps the return
address may also be a jump target from some earlier line of the code.)
Previously, this resulted in task stack frames turning up incorrectly in the backtrace, ie
Backtrace: 0x400d22a0:0x3ffb0fa0 0x40085a3c:0x3ffb0fc0 0x400f32c4:0x3ffb0fe0 0x40081965:0x3ffb1010
0x400d22a0: esp_vApplicationIdleHook at /home/esp/esp-idf/components/esp32/./freertos_hooks.c:
52
0x40085a3c: prvIdleTask at /home/esp/esp-idf/components/freertos/./tasks.c:4431
0x400f32c4: i2c_isr_handler_default at /home/esp/esp-idf/components/driver/./i2c.c:598
0x40081965: _xt_lowint1 at xtensa_vectors.o:?
Fix is to implement abort() via an unhandled exception rather than a breakpoint, I think
because of relative priority of exception types.
Another approach would be to assign a software-only INUM to abort()ing and defined a
PANIC_RSN_ABORTED, but this is more complex and interrupt numbers are more scarce than RAM!
When ‘reset halt’ command is executed, OpenOCD will take the APP CPU
out of reset and enable the clock. At this point, user can set a
breakpoint on code which will run on APP CPU. Previously, app startup
code would do another reset of APP CPU, thereby removing any breakpoints
which may have been set. This change makes APP CPU reset conditional on
DPORT_APPCPU_CLKGATE_EN bit, which is 0 by default but is set to 1 by
OpenOCD after reset.
To increase the chances that the examples work out of the box, this
change is raising the default deep sleep wakeup delay to 1ms.
If GPIO15 is low at startup, ROM code takes less time to execute
(because no logging is performed), so more time may be needed to allow
flash chip to become ready.
Fix Dport access in interrupts
Dport accesses would re-enable interrupts unconditionally, breaking things when called in an ISR. This saves and restores the interrupt status, fixing this.
This fixes a crash in the SPI slave driver, and possibly other things.
See merge request !772
1. Name change from chopper to carrier, block diagram update, minor changes to example codes
2. mcpwm_reg.h changed, brought uniformity in comments, worked on suggestions, duty to accept float. Some name changes!
3. Minor readme changes and Indetation
4. Minor change: move mcpwm_reg.h and mcpwm_struct.h to new path
5. Minor change: addition of BLDC example code and Readme
6. Name changed from epwm to mcpwm
7. Improve the reg name in mcpwm_struct.h
8. Name change chopper>carrier, deadband>deadtime
1. Enlarge wifi task stack size by 512Bytes to fix potential stack overflow issue
2. Modify wifi hmac tx queue size from 12 to 32 because we already limit the buffer number in ebuf
management module
add API to get chip info
This change adds an API to get chip info, such as chip model, enabled capabilities, size of embedded flash, silicon revision.
Hello_world example is modified to print out the information about the chip. The example is also simplified by moving all code into the main task.
Ref TW12031.
See merge request !549
esp32: update wifi lib for some bugfix
1. Fix wifi ebuf free twice issue
2. Fix wifi internal assert issue
3. Fix a bug in esp_wifi_stop
4. Fix wifi crash issue
5. Fix wifi run out of memory when 10 udp connection stability test
See merge request !745
Optimize configuration of base MAC address
Application developer can call APIs to configure base MAC address
instead of using menuconfig.
See merge request !744
component/esp32 : fix dualcore bug
1. When dual core cpu run access DPORT register, must do protection.
2. If access DPORT register, must use DPORT_REG_READ/DPORT_REG_WRITE and DPORT_XXX register operation macro.
See merge request !742
1. When dual core cpu run access DPORT register, must do protection.
2. If access DPORT register, must use DPORT_REG_READ/DPORT_REG_WRITE and DPORT_XXX register operation macro.
SPI: Various fixes (examples, mem leak, arg check)
- Fix SPI master example to use DMA-capable memory for display initialization. Fixes https://github.com/espressif/esp-idf/issues/551
- SPI master: Do not leak DMA descriptor pointer array on free
- SPI Master/Slave: Check if DMA'ed buffers actually live in DMA-capable memory
See merge request !735
component/bt: fix some bugs related to bluetooth sniff mode in controller
1. fix some bugs in bluetooth sniff mode in controller
2. export some symbols to esp32.rom.ld including functions and global variables in ROM code
3. update libbtdm.a which includes "IRAM_ATTR" addition or removal for some functions
See merge request !729
1. fix some bugs in bluetooth sniff mode in controller
2. export some symbols to esp32.rom.ld including functions and global variables in ROM code
3. update libbtdm.a which includes "IRAM_ATTR" addition or removal for some functions
esp32: select 8M clock as RTC_FAST_CLK on startup
Even though RTC_CLK_CONFIG_DEFAULT correctly had RTC_FAST_FREQ_8M as the
fast clock, the bootloader modified fast_freq field to the currently
selected RTC_FAST_CLK (so that the clock choice is not affected by the
bootloader). The application startup code never switched to 8M clock,
which caused the default (XTAL/4) to be used as RTC_FAST_CLK. This had
caused a number of issues, such as touch pads not working in deep sleep.
Fixes https://github.com/espressif/esp-idf/issues/542.
Ref TW12053.
See merge request !709
optimize scan before station connecting to AP
1. Store the information of AP(ssid, password, bssid, channel, etc)
into nvs when station connects to AP successfully. If station
connects to the same AP next time, it will scan the stored channel of the AP
first.
2. Add a parameter of channel for scanning before connecting to AP.
If the channel is set to 0, station will scan full channels. If it
is set to 1~13, station will only scan the channel.
See merge request !704
1. Store the information of AP(ssid, password, bssid, channel, etc)
into nvs when station connects to AP successfully. If station
connects to the same AP next time, it will scan the stored channel of the AP
first.
2. Add a parameter of channel for scanning before connecting to AP.
If it is set to 1~13, station will scan starting from the channel.
If the channel of AP is unknown, set it to 0.
Even though RTC_CLK_CONFIG_DEFAULT correctly had RTC_FAST_FREQ_8M as the
fast clock, the bootloader modified fast_freq field to the currently
selected RTC_FAST_CLK (so that the clock choice is not affected by the
bootloader). The application startup code never switched to 8M clock,
which caused the default (XTAL/4) to be used as RTC_FAST_CLK. This had
caused a number of issues, such as touch pads not working in deep sleep.
Fixes https://github.com/espressif/esp-idf/issues/542.
Ref TW12053.
esp32: Core dump sanity checks
Adds sanity checks when doing core dump to flash
- CRC for core dump flash partition config
- Tasks with corrupted TCBs are skipped
- Assertions to check that nothing is written beyond core dump flash partition
Ref TW11879
See merge request !686
- CRC for core dump flash partition config
- Tasks with corrupted TCBs are skipped
- Assertions to check that nothing is written beyond core dump flash partition
- RTC_CNTL_SLOWCLK_FREQ define is removed; rtc_clk_slow_freq_get_hz
function can be used instead to get an approximate RTC_SLOW_CLK
frequency
- Clock calibration is performed at startup. The value is saved and used
for timekeeping and when entering deep sleep.
- When using the 32k XTAL, startup code will wait for the oscillator to
start up. This can be possibly optimized by starting a separate task
to wait for oscillator startup, and performing clock switch in that
task.
- Fix a bug that 32k XTAL would be disabled in rtc_clk_init.
- Fix a rounding error in rtc_clk_cal, which caused systematic frequency
error.
- Fix an overflow bug which caused rtc_clk_cal to timeout early if the
slow_clk_cycles argument would exceed certain value
- Improve 32k XTAL oscillator startup time by introducing bootstrapping
code, which uses internal pullup/pulldown resistors on 32K_N/32K_P
pins to set better initial conditions for the oscillator.
XTAL frequency detection, support for selecting XTAL frequency
This MR adds more robust XTAL frequency detection code (which gets run in the bootloader) and an option to set XTAL frequency in Kconfig. By default we still use autodetection, since it is more reliable than the one used in ROM code.
This will help with issues about XTAL frequency detection in high ambient temperature conditions.
Ref TW12008
See merge request !694
esp32: update wifi lib for limitting dynamic wifi buffer
Add limit for all dynamic wifi ebuf to avoid wifi run out of memory in some extreme scanrio.
The default max allocated dynamic tx buffer is 32
The default max allocated dynamic rx buffer is 64, make default value is bigger because when all packets we received are small packets, e.g. the length is 64Bytes, then 64K can hold 1000 packets, so 64 maybe a good candidate default value, anyway the customer can configure it via menuconfig.
The default dynamic wifi internal long/long-long mgmt is 32, generally 32 is enough for mgmt packet (beacon/auth/assoc/probe/null etc). Generally when all the 32 mgmt buffer is run out of memory, it means internal wifi state machine may has problem, we need to debug it.
See merge request !683
There are some RODATAs of libphy.a that are called in ISR. So need
to put them into DRAM to avoid access them when R/W SPI flash. Due
to the RODATAs which are called in ISR haven't been picked out to
put into DRAM, put all of the RODATA of libphy.a into DRAM. This
will be optimized in the future.
Base MAC address can be stored in default manufacture-defined or customer
pre-defined place in EFUSE and other place e.g. flash or EEPROM.
If choose to use base MAC address which is stored in other place, please
call esp_base_mac_addr_set_external() before initializing WiFi/BT/Ehternet.
Remove ESP_EARLY_LOGI before bss is initialized; it crashes the CPU
There's an ESP_EARLY_LOGI line that can get called before the BSS is initialized; the early logging code doesn't cope well with that: it checks if FreeRTOS is up, but the variables it uses for that contains garbage because it isn't cleared yet, giving the wrong result. The logging code then tries to set a mux, crashing the entire system. This patch removes the log line and adds a warning at the BSS initialization line not to do anything complex before that point.
Fixes https://github.com/espressif/esp-idf/issues/523
See merge request !671
- Implements application tracing module which allows to send arbitrary
data to host over JTAG. This feature is useful for analyzing
program modules behavior, dumping run-time application data etc.
- Implements printf-like logging functions on top of apptrace module.
This feature is a kind of semihosted printf functionality with lower
overhead and impact on system behaviour as compared to standard printf.
Detect invalid cache access
This MR adds always-on feature which detects cache invalid access and triggers panic handler when invalid access interrupt is raised.
See merge request !660
Confusion here is that original ROM has two functions:
* SPIReadModeCnfig() - sets mode, calls enable_qio_mode/disable_qio_mode
* SPIMasterReadModeCnfig() - As above, but doesn't set QIO mode in status register
However we never want to use the ROM method to set/clear QIO mode flag, as not all flash chips work this way. Instead we
do it in flash_qio_mode.c in bootloader.
So in both cases (ROM or "patched ROM") we now call SPIMasterReadModeCnfig(), which is now named
esp_rom_spiflash_config_readmode().
Introduce soc component, add source of rtc_clk and rtc_pm libraries
This MR adds parts of the RTC library source code (initialization, clock selection functions, sleep functions). WiFi-related power management functions are kept inside the precompiled library. Most of RTC library APIs have been renamed.
Default CPU frequency option in Kconfig is set to 160MHz, pending qualification of 240MHz mode at high temperatures.
Register header files are moved into the new soc component, which will contain chip-specific header files and low-level non-RTOS-aware APIs (such as rtc_ APIs). Some of the files from ESP32 component were also moved: cpu_util.c, brownout.c, and the corresponding header files. Further refactoring of ESP32 component into more meaningful layers (chip-specific low level functions; chip-specific RTOS aware functions; framework-specific RTOS-related functions) will be done in future MRs.
See merge request !633
1) fixed SPI_read_status: added check for flash busy flag in matrix mode
2) fixed SPI_page_program: enable write before writing data to SPI FIFO
3) SPI flash ROM funcs replacement is controlled via menuconfig option
esp32: initialize cross-core interrupt in single core mode
The software interrupt originally used as the cross-core interrupt is
now also used to yield from a FreeRTOS critical section; therefore it
must be initialized for single core mode as well.
Fixes https://github.com/espressif/esp-idf/issues/496
See merge request !640
fix warnings generated by ESP_ERROR_CHECK(variable) in release builds
This uses the same pattern as “assert” in release builds to silence the
warning. At the same time, we make sure that if a statement is wrapped
into ESP_ERROR_CHECK, it is executed in release build as well.
Fixes https://github.com/espressif/esp-idf/issues/497
See merge request !641
This uses the same pattern as “assert” in release builds to silence the
warning. At the same time, we make sure that if a statement is wrapped
into ESP_ERROR_CHECK, it is executed in release build as well.
The software interrupt originally used as the cross-core interrupt is
now also used to yield from a FreeRTOS critical section; therefore it
must be initialized for single core mode as well.
Fixes https://github.com/espressif/esp-idf/issues/496
If static tx buffer is selected, WiFi tx buffers are allocated when WiFi is initialized and released
when WiFi is de-initialized. If dynamic tx buffer is selected, WiFi tx buffer is allocated when tx
data is delivered from LWIP to WiFi and released when tx data is sent out by WiFi.
The size of each static tx buffers is fixed to about 1.6KB and the size of dynamic tx buffers is
depend on the length of the data delivered from LWIP.
If PSRAM is enabled, "STATIC" should be selected to guarantee enough WiFi tx buffers.
If PSRAM is disabled, "DYNAMIC" should be selected to improve the utilization of RAM.
ULP coprocessor toolchain integration
- build system support for ULP coprocessor toolchain
- documentation for ULP coprocessor instruction set
- documentation for ULP code execution flow, loading programs, exchanging data
- example: counting pulses using ULP
See merge request !394
Reset WIFI mac when wifi start and update wifi lib
1. reset wifi mac when wifi start
2. roll back rx hung workaround for beacon timeout
3. fix amsdu ap interface wrong issue
4. fix amsdu header parse error
5. fix amsdu flag wrong issue
6. PHY: V350, fix BT rssi bug
7. RTC: V225, fix bt will be not work when wifi is reset
See merge request !606
SPI flash operations lock for shorter periods
Based on bug report here:
https://esp32.com/viewtopic.php?f=13&t=1489&p=6816#p6773
Long SPI flash erase (and possibly write/read) cycles block all tasks on both CPUs for an extended period, and can lead to WiFi dissassociation (and general priority inversion.)
This MR inserts preemption breaks into large operations (all erases, writes every 8KB, reads every 16KB).
Overhead of a single spi_flash_guart_start()/spi_flash_guard_end() cycle measured at approx 67us (assuming no preemption.)
See merge request !600
Error handling in NVS initialization
Previously nvs_flash_init worked under an assumption that there should always be at least one free page available. This is true during normal operation, but in some cases (such as when changing application partition table from a non-OTA to an OTA one), NVS partition may get truncated, which will cause empty pages to be lost.
This MR adds error checks for this condition, and updates code which calls `nvs_flash_init` to check for the return code.
For most examples, a simple `ESP_ERROR_CHECK` is added around `nvs_flash_init`. For NVS examples and the OTA example, more robust error handling is added.
This change also removes nvs_flash_init calls from examples which don't use NVS.
See merge request !582
idf_monitor: Small fixes (baud rate, EOL, /dev/tty.X on macOS, Ctrl-T on failure)
* "make monitor" now passed the configured baud rate.
Closes#436https://github.com/espressif/esp-idf/issues/436
* Pass toolchain prefix from sdkconfig into monitor tool
* Allow setting EOL in idf_monitor.py, use CRLF by default
* Detect if /dev/tty.X is used on macOS, warn and replace with /dev/cu.X
* If a build fails or gdb exits, ignore Ctrl-T (allowing Ctrl-T Ctrl-A/F to be same key sequence everywhere)
* Add a note about winpty on Windows.
Ref 02fdf8271d (commitcomment-21369196)
* Fix problems with Console.cancel() not existing in older pyserial
* Print more user-friendly symbols for "start of iram" and "start of flash"
See merge request !594
1. reset wifi mac when wifi start
2. roll back rx hung workaround for beacon timeout
3. fix amsdu ap interface wrong issue
4. fix amsdu header parse error
5. fix amsdu flag wrong issue
6. PHY: V350, fix BT rssi bug
7. RTC: V225, fix bt will be not work when wifi is reset
This is to avoid confusion when idf_monitor prints the first symbol in each section, ie "WindowOverflow4" or similar,
when bootloader prints the section mapping address.
Closes#447https://github.com/espressif/esp-idf/issues/447
1. Add low speed channels for LEDC module.
2. Improve fade object allocate mechanism.
3. Improve ledc example, add 2 low speed channels in example.
4. Remove debug code
5. Improve the register bit field name of slow clock.
1. add options to disable nvs
2. add station keepalive with softap
3. fix beacon rx start time not accurate issue
4. set wifi rx desc/buffer boundary check to internal memory boundary
add wakeup from touch sensor, and deep sleep example
- add new deep sleep wakeup mode
- change documentation to explain incompatibilities between different wakeup mode, add error checks
- add new ULP instructions necessary for ULP wakeup scenario
- fix issues with I_WR_REG, I_SLEEP, I_END instructions
- add deep sleep example, illustrating the use of timer, gpio, touch, and ULP wakeup triggers
See merge request !461
component/bt: optimize stack size of Bluetooth Tasks and make them be configurab…
Bluetooth tasks' stack size are optimized and can be configured by the CONFIG_NEWLIB_NANO_FORMAT option.
See merge request !559
Allow separate ethernet & wifi configuration
If only 1/2 of ethernet & WiFi are enabled in config, the other interface is no longer linked into the firmware.
* Fixes bug where enabling Ethernet but not WiFi would fail to compile.
* Also means that enabling WiFi but not Ethernet no longer links some unused ethernet interface functions.
See merge request !525
Feature/add user set mac
1. Add menuconfig for user to set mac address of wifi, bt and ethernet.
2. Add the number of MAC address generated from efuse for user to choose.
3. Add MAC address derive method.
See merge request !542
1. RTC V214: modify APLL function for the chip of ECO version.
2. Add API phy_close_rf() and use it in esp_phy_deinit() instead of pm_close_rf().
3. RTC V213: fix BT will not work when BT-init is called more than once.
Optimize or release memory in bluetooth
1. add option to release about 30K from BT if BLE only
2. later BT/BLE will be separated by BT/BLE macro, but this option should use when user make sure that in BLE only mode.
See merge request !520
This change adds esp_deep_sleep_get_wakeup_cause, which returns the
source which has caused wakeup from deep sleep.
Similar to esp_deep_sleep_get_ext1_wakeup_status, a function is added
to check touch pad wakeup status: esp_deep_sleep_get_touchpad_wakeup_status.
This function returns the touch pad which has caused wakeup.
ULP and touch FSMs in ESP32 revisions 0 and 1 do not operate correctly
if RTC_PERIPH power domain is force powered on (ESP_PD_OPTION_ON).
Both ULP and touch still work, but clock frequency of the ULP may be
incorrect and touch values may be off by considerable amount. As such,
when these wakeup modes are used, RTC_PERIPH power domain has to be set
to ESP_PD_OPTION_AUTO (or, in the current implementation,
ESP_PD_OPTION_OFF — though this will change in the future when _OFF will
actually *force* the power domain to be powered off).
Because EXT0 wakeup source requires RTC_PERIPH to be powered ON, mark
ULP and touch wakeup sources as incompatible with EXT0. Workaround for
this is to use EXT1 wakeup source instead, which offers similar or
better functions without having to keep RTC_PERIPH powered on.
