These directories provide the implementation of the porting layer on the Espressif ESP-IDF platform plus the associated build and board configuration information. Instructions on how to install the necessary tools and perform the build can be found in the MCU directories below.
- app: contains the code that runs the application (both examples and unit tests) on the ESP-IDF platform.
- src: contains the implementation of the porting layers for ESP-IDF.
- mcu: contains the configuration and build files for the MCUs supported on the ESP-IDF platform.
- u_cfg_os_platform_specific.h: task priorities and stack sizes for the platform, built into this code.
- test: contains tests that use ESP-IDF application APIs to check out the integration of
ubxlibinto ESP-IDF, e.g. at PPP level beneath LWIP.
ubxlib depends on very few ESP-IDF components (see the directories beneath this one for how to perform a build) but note that, if you wish to include a PPP-level integration at the base of the ESP-IDF LWIP stack, allowing use of native ESP-IDF clients (e.g. MQTT) with a cellular connection, then you must define U_CFG_PPP_ENABLE when building ubxlib; you can do this by appending it to the COMPILE_DEFINITIONS ESP-IDF CMake variable in your top-level CMakeLists.txt file as follows:
add_compile_definitions(U_CFG_PPP_ENABLE)
...or by including it in the U_FLAGS environment variable which the ubxlib ESP-IDF component looks for. Note that adding U_CFG_PPP_ENABLE to target_compile_options() is NOT sufficient since the target compile options are not applied to components, and ubxlib is brought in as an ESP-IDF component.
You can find an example of how to make a sockets connection using native Espressif function calls in main_ppp_espidf.c.
To bring in the right ESP-IDF components and compilation flags, you can do that through menuconfig by going to Component Config and making sure that ESP NETIF Adapter --> TCP/IP Stack Library (LwIP) --> LwIP is ticked; also make sure that LWIP --> Enable PAP support and, if your network operator requires a user name and password along with the APN AND requires CHAP authentication, then also LWIP --> Enable CHAP support, are ticked.
Alternatively, if you prefer to do this by hand, make sure that your sdkconfig file contains:
CONFIG_LWIP_PPP_SUPPORTCONFIG_ESP_NETIF_TCPIP_LWIPCONFIG_LWIP_PPP_PAP_SUPPORT- if your network operator requires a user name and password along with the APN AND requires CHAP authentication, then also switch on
CONFIG_LWIP_PPP_CHAP_SUPPORT
...and, if you are minimising the components built into your main application then you should add the ESP-IDF component esp_netif to the list. If you fail to do this your code will either fail to link because _g_esp_netif_netstack_default_ppp could not be found, or the initial PPP LCP negotiation phase with the module will fail.
You must also call esp_netif_init() followed by esp_event_loop_create_default(), once only, at start of day (i.e. before opening the ubxlib device) from your application code, otherwise ESP-IDF will not work correctly or will assert because of an invalid mbox somewhere in the IP stack at the point that a cellular connection is made.