1. add sens_struct.h
2. add definition of RTCCNTL and RTCIO
3. modify touch pad examples
4. update example code.
5. add comments add option in menuconfig
6. fix issue that pad index 8 and 9 are mismatched
7. add touch_pad_read_filtered() api to get value filtered by iir filter
8. modify touch pad isr func
9. Make the items in perihperal.ld in the sequence of address
10. delete Kconfig for touch pad
11. add touchpad filter APIs to adjust the filter
12. add touch_pad into index.rst
13. add touch_pad in Doxyfile
14. add touch_pad.rst
- the first characteristic is used to receive data from client.
- the second characteristic is used to notify data to client.
- the third characteristic is used to receive command from client, user
can add code to process the command.
- the fourth characteristic is used to notify status to client.
- the fifth characteristic is used to keep ble connection
component/bt: cherry-pick the bugfix/btdm_api_manage_pair_info_#13119 to this branch.
component/bt: Change the ble gap API code format & added the status judgment in the btc_storage_load_bonded_ble_devices function.
1. Hello World application shows no footprint difference before and
after this change
2. examples/ethernet/ethernet application compiles properly (can't
test with my board)
Remove wifi config option
Remove Wi-Fi enable/disable option from Kconfig. This can be detected by the presence of esp_wifi_init() function in the application. Minimum footprint impact after the change.
See merge request !1098
1. Rename api from rmt_get_ringbuf_handler to rmt_get_ringbuf_handle (Github Issue #274)
2. doxygen param rename
3. change API rmt_wait_tx_done to specify maximum waiting time
4.Change return type of rmt_wait_tx_done API from bool to esp_err_t
5. update doc
SD SPI mode driver
This MR adds functionality to support SD cards connected via SPI interface.
Additionally, two bugs are fixed:
- Definition of `SPI_TRANS_MODE_DIOQIO_ADDR` in spi_master driver
- SD card probing frequency was 4000kHz instead of 400kHz as required by the standard
See merge request !727
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.
unused variable 'lfn'
'isr_handler' defined but not used
'servo_set_angle' defined but not used
'gpio_test_signal' defined but not used
'change_duty' defined but not used
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
- Fix slave initiate service discovery procedure
- Fix master re-discovery every time connection established
- Optimize service discovery char ccc write procedure
- Optimize esp_log_buffer function
- Modify default supervision timeout from 20s to 2s
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.
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
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
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/bt: fix adv stop event bug and add attribute table create
- Fix bug that advertising stop event produced while calling start_adv function
- Modify gatt server adv data and scan rsp data raw setting
- Add create attribute table error msg
- Delete redundant printf in previous commits
See merge request !739
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
error
- Fix bug that advertising stop event produced while calling start_adv function
- Modify gatt server adv data and scan rsp data raw setting
- add create attribute table error msg
- Delete redundant printf in previous commits
I2S driver - fixed support for 24 and 32-bits, fixed tx/rx at the same time
- Modify sample can test with 24, 32-bits audio
- Add i2s sample README
- simply i2s_push function
- change sample rates, bits per sample, channel on fly
See merge request !483
Feature/btdm ble bt separa
@Jack @snake @igrokhotkov @angus @island please help to review the code.
Separate the bt/ble code. After the separate, can save 15k~25k ram & 240k~460k code size(depending on the menuconfig).
See merge request !684
Split common SPI stuff out of master driver; add slave driver; add workaround for DMA issue.
This merge req mainly adds a slave device. In order to do this, the original master driver is refactored into common code shared by master and slave modes, and a slave driver is added.
The other things added are:
- Added a workaround for a 'feature' of the ESP32 silicon that can lock up the receive DMA channel in some situations. This can only be fixed by resetting *both* DMA channels. The workaround implemented makes sure that the reset only happens when both channels are idle
- Got rid of the automatic choice between register- and DMA-based transfers. The master (and slave) code will now always go for a DMA transfer if a DMA channel is given, and always go for register-based transfers if no DMA channel is given.
- Add in a bunch of fixes for outstanding Github issues.
See merge request !659
Add support 24, 32 bits
@jxmao optimize i2s_zero_buffer
@jxmao correct config support slave mode
@jxmao correct setup pin support tx/rx at the same time
Enhance pin power
@jxmao add dynamic change number of channels
remove nvs_init
remove start log and enhance power pin setup
using enum for i2s_channel and i2s_bits_per_sample, return ESP_ERR_INVALID_ARG when check params
validate i2s_bits_per_sample and channel
check tx & rx buffer before fill zero
remove checking channel as @jxmao suggest
limit dma buffer
modify i2s pin back to gpio mux before configure gpio matrix, resolve github issue #512
Add support 24, 32 bits
reduce push function
Modify sample can test with 24, 32-bits
Add i2s sample README
Fixed i2s_set_clk got reset sometime
can changes bit-wide while running
Fix sample rate calculation for DAC mode from @jeroen
modify example can change bits per sample every 5 seconds
cleanup
add comment for bytes_per_sample
update as @angus suggestions
Add i2s_set_clk api
I2S driver bug fixed as following log:
@jxmao optimize i2s_zero_buffer
@jxmao correct config support slave mode
@jxmao correct setup pin support tx/rx at the same time
Enhance pin power
@jxmao add dynamic change number of channels
remove nvs_init
remove start log and enhance power pin setup
using enum for i2s_channel and i2s_bits_per_sample, return ESP_ERR_INVALID_ARG when check params
validate i2s_bits_per_sample and channel
check tx & rx buffer before fill zero
remove checking channel as @jxmao suggest
limit dma buffer
modify i2s pin back to gpio mux before configure gpio matrix, resolve github issue #512
limit dma buffer to 4092
change gpio_matrix_*_check to inline function, remove some comments and rename test_i2s function to setup_triangle_sine_waves
for change commit title
add support for 32k XTAL as RTC_SLOW_CLK source
- 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.
Ref TW11683.
Ref https://esp32.com/viewtopic.php?f=13&t=1570
Fixes https://github.com/espressif/esp-idf/issues/337.
See merge request !696
- 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.
wear levelling
This MR adds wear levelling component. It presents an interface similar to the interface of spi_flash and esp_partition. Inside, it stores data inside a partition to in a way that reduces worst case number of erase cycles for any given sector.
Also included are APIs similar to the ones provided for SDMMC to mount FAT filesystem on top of the wear levelling partition. A simple example shows how this API can be used.
Ref TW10338.
See merge request !567
Fix device_name check in gatt_client example
`strcmp` was used against `adv_name` array, which was not a zero terminated string, causing `strcmp` check to fail for valid names.
Ref. https://github.com/espressif/esp-idf/pull/502
See merge request !652
Feature/btdm avrc
The source branch "feature/btdm_avrc" includes classic Bluetooth profiles A2DP(sink role) and AVRCP(controller role);
Menuconfig options to control whether to enable classic BT is added.
See merge request !591
wifi performance: add wifi performance examples including TCP&UDP TX/RX
Add wifi performance examples including TCP and UDP send and receive.
See merge request !577
request new lines must be `\r\n` as specified in the HTTP RFC.
Also the following logic checks for the socket to be closed by the server. This only happens with HTTP/1.0 not HTTP/1.1. So I have adjusted the protocol in the request, too.
You can set esp32 as AP/STA, client/sever, sender/recever in menuconfig.
You can set whether to display delay time info in menuconfig.
Now you can transfer data between esp and esp.
examples: Standardise naming of files, symbols, etc. in examples
* Use "example" in all example function & variable names,
ie use i2c_example_xxx instead of i2c_xxx for example functions.
Closes#198https://github.com/espressif/esp-idf/issues/198
* Mark example functions, etc. static
* Replace uses of "test" & "demo" with "example"
* Split the UART example into two
* Rename "main" example files to end with "_main.c" for disambiguation
See merge request !601
* Use "example" in all example function & variable names,
ie use i2c_example_xxx instead of i2c_xxx for example functions.
Closes#198https://github.com/espressif/esp-idf/issues/198
* Mark example functions, etc. static
* Replace uses of "test" & "demo" with "example"
* Split the UART example into two
* Rename "main" example files to end with "_main.c" for disambiguation
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
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.
nvs_flash_init may return an error code in some cases, and applications
should check this error code (or at least assert on it being ESP_OK, to
make potential issues more immediately obvious).
This change modifies all the examples which use NVS to check the error
code. Most examples get a simple ESP_ERROR_CHECK assert, while NVS
examples, OTA example, and NVS unit tests get a more verbose check which
may be used in real applications.
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
Examples on using capacitive touch sensors
- `touch_pad_read` - read sensor values and show on terminal
- `touch_pad_interrupt` - perform simple calibration; trigger an interrupt when any pad is touched
See merge request !530
esptool version bump and new "espefuse.py set_flash voltage" command
* New "espefuse.py set_flash_voltage" command to easily set a fix
VDD_SDIO regulator voltage (1.8V, 3.3V or disabled).
* Fixes bugs when flashing files with non-4-byte aligned lengths
(doesn't effect esp-idf image files)
* esptool README improvements
* Detect overlapping files in write_flash
* read_mac now works correctly on ESP32
* Integrates reset fix for older dev boards (formerly the "Windows ESP32R0 reset workaround")
See merge request !481
* New "espefuse.py set_flash_voltage" command to easily set a fix
VDD_SDIO regulator voltage (1.8V, 3.3V or disabled).
* Fixes bugs when flashing files with non-4-byte aligned lengths
(doesn't effect esp-idf image files)
* README improvements
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
Partition/SPI/OTA docs & OTA new functionality
* Update partition, SPI flash & OTA docs to reflect functionality changes
* Refactor OTA implementation to perform checks mentioned in API doc
* Add new functions to OTA API: esp_ota_get_running_partition() & esp_ota_get_next_update_partition() functions
* Add spi_flash_cache2phys() & spi_flash_phys2cache() functions to support esp_ota_get_running_partition()
See merge request !513
1. indicate adv/scan start complete success or failed
2. controller do limit of adv/scan concurrence, so add some codes to report adv/scan start failed or not.
1. add new APIs bt controller enable/disab/deinit
2. make bt controller work need to call two APIs of esp_bt_controller_init and enable
3. modify phy init to make mac reset once
Verify 0xE9 magic byte on first write, verify entire image before
switching.
Enable verification for secure boot signature (was using invalid ifdef
guard)
In the existing tree, after a connected client disconnects the device
will never re-enter the advertising state. Additional clients will not
be able to discover or connect to the device. This patch forces the
device back into the advertising state upon disconnection.
Resolves Pull Request #217https://github.com/espressif/esp-idf/pull/217
Organize examples and API documentation - supplement to !430
This supplement to !430, both intended to replace bulky !421.
1. Fixed broken links
2. Added links to available examples in API documentation, where missing
3. Updated links to point directly to example folder (to show README.md with example description)
4. Added README.md in docs folder info to point reader to ReadTheDocs instead of doc sources, ref. https://github.com/espressif/esp-idf/issues/243
5. Fixed some typo errors / Sphinx warnings
6. Fixed memory leak in example, ref. https://github.com/espressif/esp-idf/issues/209
See merge request !440
If using WIFI_INIT_CONFIG_DEFAULT, error message will point out lack
of WiFi. Otherwise linker errors on WiFi symbols should help give a
clue as to what is broken.
Piggy-backs on changes in !420, ref github #230#237
- low level on GPIO12 corresponds to 3.3V output, not 1.8V
- add espefuse.py commands to burn efuses
- add XPD_SDIO_REG to the list of efuses which must be set
Reported on the forum: http://esp32.com/viewtopic.php?f=2&t=849&start=10#p4170
component bt:Added the create attribute table method to the new API
GATT Server service table APIs.
Have already modify the style and other things as @jeroen suggestion in other MR(the MR have been closed)
See merge request !399
Clean up WiFi & Bluetooth config options
* Splits "WiFi" configuration out from ESP32 configuration submenu to its own menu.
* Renames "BT" to "Bluetooth", enabling Bluetooth is now in this option not the ESP32 submenu.
* Also disables compiling/linking of BT stack if Bluetooth is disabled, saves some build time.
See merge request !397
examples/10_openssl_server: fixup SSL server with method of specific version
1. add method of any version supporting at OpenSSL and add API in header file
2. change OpenSSL server context method to be method of any version
Fixes http://esp32.com/viewtopic.php?f=14&t=696.
See merge request !369
SPI master driver
This merge requests adds an SPI Master driver. This driver is (of course) multithread capable, has device abstraction, has command queueing, DMA support and all other sorts of nice things you'd expect from a SPI driver.
See merge request !332
1. add fading functions.
2. clear up ledc.c and ledc.h
3. update api doc.
4. add ledc example
5. edit ledc.rst and add readme for example code.
6. add s_ prefix for static global values.
7. add mutex for fade functions
8. minor changes according to the comments.
1. add method of any version supporting at OpenSSL and add API in header file
2. change OpenSSL server context method to be method of any version
Fixes http://esp32.com/viewtopic.php?f=14&t=696.
2. update example comments and other minor changes
3. rename API: i2c_cmd_link_create/i2c_cmd_link_delete (+4 squashed commits)
Squashed commits:
[2e0ac3e] 1. coding style: add one space after condition key words.
2. modify i2c.h, use gpio_num_t instead of int, improve comments of return values
3. add i2c index in index.rst
4. add readme for i2c example
[4991d92] update i2c.doc
[88b672e] driver: i2c
1. add mux and spin lock to run in a thread-safe way.
2. modify example code
[4eb15fe] driver: i2c code
1. add i2c master code
2. add i2c slave code
3. add i2c example code
4. add DRAM_ATTR for I2C array
1. add ISR handler apis so that users of different layers can hook their own isr handler on different GPIO.
Audio project has different software layers, they need different gpio isr handler for layer instead of processing all GPIO interrupts in one handler.
If this kind of calling a handler from isr is not proper, please kindly point out.
2. add gpio example code.
3. improve gpio.rst
4. add readme for gpio example
Squashed commits:
[278e50f] update: GPIO
1. coding style, add a space between conditional or loop keyword and an opening paren.
2. modify some return value and doc
3. use printf in example code
Squashed commits:
[efb23bb] minor change of comment
1. The transmitting mode of the packets from LWIP to MAC is changed from synchronous to asynchronous.
2. The receive buf mode : support pointer mode and copy mode.
3. Add get phy status func used to config mac register.
1. change all gatt cb function to 3 args and function type. add gattc_if/gatts_if as second argument
2. delete gatt_if of "gatt cb param"
3. separate conn_id and gatt_if from conn_id
4. change the demo code as the gatt changed
1. add sigma-delta code and example.
2. add gpio output signal in io matrix.
Squashed commits:
[a25e7d4] minor changes for doc
[6a03a1e] minor changes on comments and doc.
[97dd9e4] Add doc.
update index.rst
change example index
Add dynamic interrupt allocation mechanism
This adds:
- Dynamic allocation of interrupts. Pass it the features of the interrupt you want, it'll set you up with an int.
- Shared interrupts. Enables multiple peripheral drivers to use the same interrupt.
- Marking what interrupts are fully executable from IRAM; if an int isn't marked like that it will get disabled once flash cache gets disabled.
Also:
- Modifies driver to be in line with these changes
See merge request !254
Fail CI build on warnings
This allows developers to add CFLAGS for -Wno-error=XXX while developing, but before code passes the CI build then it must be warning-free.
See merge request !279
Feature/btdm bluedroid
This branch contain the bluedroid host code.
Currently, Only GAP/GATT SERVER/GATT CLIENT release to users.
Actually, the content of the codes is further more than GAP/GATT and etc.
In this release version, users only need to concern about the APIs which are in "api/include/".
Now, suggestions in comment have been resolved are following:
1. The APIs use callback function. Ivan , Jeroen and me have discussed it. Currently the code will not be changed.
2. The APIs use OPEN/CLOSE. I have ask Ivan, besides bluedroid do this, we will keep the name.
3. Coding style. I have run format.sh to handle the style. And some spell error have been fixed.
4. APIs doxygen. I have clean the warning by doxygen. But bt.rst is still need to be completed.
5. Other comment without resolved face to face that I have to add response in the comment and fix them in the code
6. Fix some incorrect things. See the git log for details.
This 1st version of bluedroid release still have lots of things to do. But it can be done after this merge.
1. Compelete the BLUFI(Bluetooth config wifi connection) documents, security, application protocol and other.
2. Add SPP-LIKE profile.
3. Do more examples codes to cover most of the APIs.
4. Test and fix bug.
Another thing：
1. Do the document of APIs.(xml->bt.rst->html)
(I will do this before merge as Ivan's suggestion)
This is already done. Besides, the union type in doxygen have something error. Ivan will fix it.
See merge request !239
driver: PCNT
1. add PCNT module in periph_ctrl.c/.h
2. add description of PCNT status in pcnt_struct.h
3. add PCNT driver code
4. add PCNT example code.
See merge request !229
system_* APIs cleanup
This changeset is mostly about cleaning up `system_*` APIs and moving them from libcore. It has dragged a few more changes along, however.
- `system_deep_sleep` deprecated, new name is `esp_deep_sleep`
- `system_efuse_read_mac` deprecated, new name is `esp_efuse_read_mac`
- `system_read/write_rtc_mem` removed (reason: we use linker to place code/data into RTC memory now)
- `system_get_sdk_version` deprecated. Returns "master" for now. Support for compile-time and runtime version detection will be done in a separate MR.
- `system_get_time` and variations have been deprecated. `gettimeofday` should be used instead.
- `system_restart` deprecated, new name is `esp_restart`. Rewritten code to work correctly from any of the cores.
- `system_restore` deprecated, `esp_wifi_restore` should be used instead.
- `system_get_rst_info` removed (it wasn't in a header file)
- RTC library has been updated to latest version
- Logging output from `libfoo.a` goes through `foo_printf` function now, where `foo ` is any of the library names. For libraries other than rtc and phy, this is a temporary measure, until we finish switching to esp_log library and clean up all uses of printf/ets_printf.
- ESP-IDF build will fail if any of the libraries have printf/ets_printf reference.
- Added `esp_random` function which gets values from HW RNG. I have added code which makes sure the value is not polled too often (allows at least 16 APB cycles). Also added a header file for HW RNG (just one register).
- Moved random number generation functions used by wpa library into wpa_supplicant component.
See merge request !234
Refs:
http://esp32.com/viewtopic.php?f=13&t=550http://esp32.com/viewtopic.php?f=13&t=551
rmt.c should include stdlib.h for malloc, esp_bignum,c &
https_request_main.c for abort().
FreeRTOSConfig.h is only including stdlib if
CONFIG_FREERTOS_ASSERT_ON_UNTESTED_FUNCTION is set. However, it is
included for abort() so needs to be included whenever
CONFIG_FREERTOS_ASSERT_FAIL_ABORT is set.
This change includes unconditionally in FreeRTOSConfig.h. This is to
avoid this kind of bug where compiler errors are dependent on config. I
suggest we don't change this to be more selective until we have 'make
randomconfig' style tests in CI.
NVS examples
Add two examples for working with NVS.
One is reading and writing an integer value, another is reading and writing a blob.
See merge request !194
Updated previusly submitted example, saved it as "07_nvs_rw_value" and
added a new one.
Overview of examples:
* 07_nvs_rw_value - simple read and write a single value
* 08_nvs_rw_blob - read and write a blob that is extened with new data
on each restart of ESP32
Removed LICENSE files
New makefile component_wrapper.mk allows some variables to be set
before component.mk is evaluated. This properly fixes problems with
sdkconfig being hard to access in all phases of the build.
Including component_common.mk is no longer necessary and will print a
deprecation warning for components which use it.
Simplifies examples of embedding a certificate file or a root cert.
This is a much cruder mechanism than the full flash filesystem we want
eventually, but still sometimes useful.
Demonstrates how to read and write a value using NVS.
The value tracks number of ESP32 module restarts.
Example also shows how to use basic diagnostics if read / write
operation was successful.
1. add new example for A2DP and the related btif layer source code is ported
2. modification on osi_alarm_new API to support periodic timer
3. enable macro BTA_AR_INCLUDED, BTA_AV_INCLUDED, BTA_AV_SINK_INCLUDED
4. The A2DP example cannot work and can only be built successfuly
