esp_modem: Moved to component folder

components/esp_modem/docs/README.md

@@ -0,0 +1,79 @@
+# ESP MODEM
+
+This component is used to communicate with modems in the command mode (using AT commands), as well as the data mode
+(over PPPoS protocol). 
+The modem device is modeled with a DCE (Data Communication Equipment) object, which is composed of:
+* DTE (Data Terminal Equipment), which abstracts the terminal (currently only UART implemented).
+* PPP Netif representing a network interface communicating with the DTE using PPP protocol.
+* Module abstracting the specific device model and its commands.
+
+```
+   +-----+   
+   | DTE |--+
+   +-----+  |   +-------+
+            +-->|   DCE |
+   +-------+    |       |o--- set_mode(command/data)
+   | Module|--->|       |
+   +-------+    |       |o--- send_commands
+             +->|       |
+   +------+  |  +-------+ 
+   | PPP  |--+ 
+   | netif|------------------> network events
+   +------+ 
+```
+
+## Modem components
+### DCE
+
+This is the basic operational unit of the esp_modem component, abstracting a specific module in software,
+which is basically configured by 
+* the I/O communication media (UART), defined by the DTE configuration
+* the specific command library supported by the device model, defined with the module type
+* network interface configuration (PPPoS config in lwip)
+
+After the object is created, the application interaction with the DCE is in
+* issuing specific commands to the modem
+* switching between data and command mode
+
+### DTE
+Is an abstraction of the connected interface. Current implementation supports only UART
+
+### PPP
+
+Is used to connect the specific network interface to the modem data mode. Currently implementation supports only PPPoS protocol.
+
+### Module
+
+Abstraction of the specific modem device. Currently the component supports SIM800, BG96, SIM7600.
+
+## Use cases
+
+Users could interact with the esp-modem using the DCE's interface, to basically
+* Switch between command and data mode to connect to the internet via cellular network.
+* Send various commands to the device (e.g. send SMS)
+
+The applications typically register handlers for network events to receive notification on the network availability and 
+IP address changes.
+
+Common use cases of the esp-modem are also listed as the examples:
+* `examples/pppos_client` -- simple client which reads some module properties and switches to the data mode to connect to a public mqtt broker.
+* `examples/modem_console` -- is an example to exercise all possible modules commands in a console application.
+* `examples/ap_to_pppos` -- this example focuses on the network connectivity of the esp-modem and provides a WiFi AP
+  that forwards packets (and uses NAT) to and from the PPPoS connection.
+
+## Extensibility
+
+### CMUX
+
+Implementation of virtual terminals is an experimental feature, which allows users to also issue commands in the data mode,
+after creating multiple virtual terminals, designating some of them solely to the data mode, while other to command mode.
+
+### DTE's
+
+Currently we support only UART, but modern modules support other communication interfaces, such as USB, SPI.
+
+### Other devices
+
+Adding a new device is a must-have requirement for the esp-component. Different modules support different commands,
+or some commands might have a different implementation. Adding a new device means to provide a new implementation
+as a class derived from `GenericModule`, where we could add new commands or modify the existing ones.

components/esp_modem/docs/advanced_api.rst

@@ -0,0 +1,48 @@
+Advanced esp-modem use cases
+============================
+
+This chapter outlines basic extensibility of the esp-modem component.
+
+.. _dce_factory:
+
+Custom instantiation with DCE factory
+--------------------------------------
+
+It is possible to create a modem handle in many different ways:
+
+- Build a DCE on top a generic module, user defined module or build the module only (in case the application will only use AT command interface)
+- Create the DCE as a shared, unique or a vanilla pointer
+- Create a generic DCE or a templated DCE_T of a specific module (this could be one of the supported modules or a user defined module)
+
+All the functionality is provided by the DCE factory
+
+.. doxygengroup:: ESP_MODEM_DCE_FACTORY
+   :members:
+
+
+Create custom module
+--------------------
+
+Creating a custom module is necessary if the application needs to use a specific device that is not supported
+and their commands differ from any of the supported devices. In this case it is recommended to define a new class
+representing this specific device and derive from the :cpp:class:`GenericModule`. In order to instantiate
+the appropriate DCE of this module, application could use :ref:`the DCE factory<dce_factory>`, but build the DCE with
+the specific module, using :cpp:func:`esp_modem::dce_factory::Factory::build`.
+
+Please refer to the implementation of the existing modules.
+
+Please note that the ``modem_console`` example defines a trivial custom modem DCE which overrides one command,
+for demonstration purposes only.
+
+
+Create new communication interface
+----------------------------------
+
+In order to connect to a device using an unsupported interface (e.g. SPI or I2C), it is necessary to implement
+a custom DTE object and supply it into :ref:`the DCE factory<dce_factory>`. The DCE is typically created in two steps:
+
+- Define and create the corresponding terminal, which can communicate on the custom interface. This terminal should support basic IO methods defined in :cpp:class:`esp_modem::Terminal` and derive from it.
+- Create the DTE which uses the custom Terminal
+
+Please refer to the implementation of the existing UART DTE.
+

components/esp_modem/docs/api_docs.rst

@@ -0,0 +1,54 @@
+.. _c_api:
+
+API Guide for C interface
+=========================
+
+
+C API is very simple and consist of these two basic parts:
+
+- :ref:`lifecycle_api` 
+- :ref:`modem_commands`
+
+Typical application workflow is to:
+
+- Create a DCE instance (using :cpp:func:`esp_modem_new`)
+- Call specific functions to issue AT commands (:ref:`modem_commands`)
+- Switch to the data mode (using :cpp:func:`esp_modem_set_mode`)
+- Perform desired network operations (using standard networking API, unrelated to ESP-MODEM)
+- Optionally switch back to command mode (again :cpp:func:`esp_modem_set_mode`)
+- Destroy the DCE handle (sing :cpp:func:`esp_modem_destroy`)
+
+Note the configuration structures for DTE and DCE, needed for creating the DCE instance, is documented in :ref:`api_config`
+
+.. _lifecycle_api:
+
+Lifecycle API
+-------------
+
+These functions are used to create, destroy and set modem working mode.
+
+- :cpp:func:`esp_modem_new`
+- :cpp:func:`esp_modem_destroy`
+- :cpp:func:`esp_modem_set_mode`
+
+.. doxygengroup:: ESP_MODEM_C_API
+
+
+.. _modem_commands:
+
+Modem commands
+--------------
+
+These functions are the actual commands to communicate with the modem using AT command interface.
+
+
+.. doxygenfile:: esp_modem_api_commands.h
+
+.. _api_config:
+
+Configuration structures
+------------------------
+
+
+.. doxygengroup:: ESP_MODEM_CONFIG
+   :members:

components/esp_modem/docs/conf.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+#
+# English Language RTD & Sphinx config file
+#
+import os
+import os.path
+import re
+import subprocess
+import sys
+
+# General information about the project.
+project = u'esp-modem'
+copyright = u'2016 - 2021, Espressif Systems (Shanghai) Co., Ltd'
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+language = 'en'
+
+extensions = ['breathe']
+
+breathe_projects = {'esp_modem': 'xml'}
+
+breathe_default_project = "esp_modem"
+
+source_suffix = ['.rst', '.md']
+
+source_parsers = {'.md': 'recommonmark.parser.CommonMarkParser', }

components/esp_modem/docs/cxx_api_docs.rst

@@ -0,0 +1,44 @@
+C++ API Documentation
+=====================
+
+Similar to the :ref:`c_api`, the basic application workflow consist of
+
+.. toctree::
+
+- :ref:`Construction of the DCE<cpp_init>`
+- :ref:`Switching modes<cpp_mode_switch>`
+- :ref:`Sending (AT) commands<cpp_modem_commands>`
+- :ref:`Destroying the DCE<cpp_destroy>`
+
+.. _cpp_init:
+
+Create DTE and DCE
+------------------
+
+.. doxygengroup:: ESP_MODEM_INIT_DTE
+
+.. doxygengroup:: ESP_MODEM_INIT_DCE
+
+
+.. _cpp_mode_switch:
+
+Mode switching commands
+-----------------------
+
+.. doxygenclass:: esp_modem::DCE_T
+   :members:
+
+.. _cpp_modem_commands:
+
+Modem commands
+--------------
+
+.. include:: cxx_api_links.rst
+
+.. _cpp_destroy:
+
+Destroy the DCE
+---------------
+
+The DCE object is created as ``std::unique_ptr`` by default and as such doesn't have to be explicitly destroyed.
+It simply gets destroyed and cleaned-up automatically if the object goes out of the block scope.

components/esp_modem/docs/cxx_api_links.rst

@@ -0,0 +1,25 @@
+
+- :cpp:func:`esp_modem::DCE::sync` 
+- :cpp:func:`esp_modem::DCE::get_operator_name` 
+- :cpp:func:`esp_modem::DCE::store_profile` 
+- :cpp:func:`esp_modem::DCE::set_pin` 
+- :cpp:func:`esp_modem::DCE::read_pin` 
+- :cpp:func:`esp_modem::DCE::set_echo` 
+- :cpp:func:`esp_modem::DCE::sms_txt_mode` 
+- :cpp:func:`esp_modem::DCE::sms_character_set` 
+- :cpp:func:`esp_modem::DCE::send_sms` 
+- :cpp:func:`esp_modem::DCE::resume_data_mode` 
+- :cpp:func:`esp_modem::DCE::set_pdp_context` 
+- :cpp:func:`esp_modem::DCE::set_command_mode` 
+- :cpp:func:`esp_modem::DCE::set_cmux` 
+- :cpp:func:`esp_modem::DCE::get_imsi` 
+- :cpp:func:`esp_modem::DCE::get_imei` 
+- :cpp:func:`esp_modem::DCE::get_module_name` 
+- :cpp:func:`esp_modem::DCE::set_data_mode` 
+- :cpp:func:`esp_modem::DCE::get_signal_quality` 
+- :cpp:func:`esp_modem::DCE::set_flow_control` 
+- :cpp:func:`esp_modem::DCE::hang_up` 
+- :cpp:func:`esp_modem::DCE::get_battery_status` 
+- :cpp:func:`esp_modem::DCE::power_down` 
+- :cpp:func:`esp_modem::DCE::reset` 
+- :cpp:func:`esp_modem::DCE::set_baud`

components/esp_modem/docs/esp_modem_api_commands.h

@@ -0,0 +1,99 @@
+// cat ../include/generate/esp_modem_command_declare.inc | clang -E -P -CC  -xc -I../include -DGENERATE_DOCS  - | sed -n '1,/DCE command documentation/!p' > c_api.h
+// cat ../include/generate/esp_modem_command_declare.inc | clang -E -P  -xc -I../include -DGENERATE_DOCS -DGENERATE_RST_LINKS - | sed 's/NL/\n/g' > cxx_api_links.rst
+
+// call parametrs by names for documentation
+
+
+//  --- DCE command documentation starts here ---
+/**
+ * @brief Sends the initial AT sequence to sync up with the device
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_sync (); /**
+ * @brief Reads the operator name
+ * @param[out] name module name
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_get_operator_name (char* name); /**
+ * @brief Stores current user profile
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_store_profile (); /**
+ * @brief Sets the supplied PIN code
+ * @param[in] pin Pin
+ * @return OK, FAIL or TIMEOUT
+ */command_result esp_modem_set_pin (const char* pin); /**
+ * @brief Checks if the SIM needs a PIN
+ * @param[out] pin_ok true if the SIM card doesn't need a PIN to unlock
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_read_pin (bool* pin_ok); /**
+ * @brief Sets echo mode
+ * @param[in] echo_on true if echo mode on (repeats the commands)
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_echo (const bool echo_on); /**
+ * @brief Sets the Txt or Pdu mode for SMS (only txt is supported)
+ * @param[in] txt true if txt mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_sms_txt_mode (const bool txt); /**
+ * @brief Sets the default (GSM) charater set
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_sms_character_set (); /**
+ * @brief Sends SMS message in txt mode
+ * @param[in] number Phone number to send the message to
+ * @param[in] message Text message to be sent
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_send_sms (const char* number, const char* message); /**
+ * @brief Resumes data mode (Switches back to th data mode, which was temporarily suspended)
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_resume_data_mode (); /**
+ * @brief Sets php context
+ * @param[in] x PdP context struct to setup modem cellular connection
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_pdp_context (struct PdpContext* x); /**
+ * @brief Switches to the command mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_command_mode (); /**
+ * @brief Switches to the CMUX mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_cmux (); /**
+ * @brief Reads the IMSI number
+ * @param[out] imsi Module's IMSI number
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_get_imsi (char* imsi); /**
+ * @brief Reads the IMEI number
+ * @param[out] imei Module's IMEI number
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_get_imei (char* imei); /**
+ * @brief Reads the module name
+ * @param[out] name module name
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_get_module_name (char* name); /**
+ * @brief Sets the modem to data mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_data_mode (); /**
+ * @brief Get Signal quality
+ * @param[out] rssi signal strength indication
+ * @param[out] ber channel bit error rate
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_get_signal_quality (int* rssi, int* ber); /**
+ * @brief Sets HW control flow
+ * @param[in] dce_flow 0=none, 2=RTS hw flow control of DCE
+ * @param[in] dte_flow 0=none, 2=CTS hw flow control of DTE
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_flow_control (int dce_flow, int dte_flow); /**
+ * @brief Hangs up current data call
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_hang_up (); /**
+ * @brief Get voltage levels of modem power up circuitry
+ * @param[out] voltage Current status in mV
+ * @param[out] bcs charge status (-1-Not available, 0-Not charging, 1-Charging, 2-Charging done)
+ * @param[out] bcl 1-100% battery capacity, -1-Not available
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_get_battery_status (int* voltage, int* bcs, int* bcl); /**
+ * @brief Power down the module
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_power_down (); /**
+ * @brief Reset the module
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_reset (); /**
+ * @brief Configures the baudrate
+ * @param[in] baud Desired baud rate of the DTE
+ * @return OK, FAIL or TIMEOUT
+ */ command_result esp_modem_set_baud (int baud);

components/esp_modem/docs/esp_modem_dce.hpp

@@ -0,0 +1,111 @@
+// cat ../include/generate/esp_modem_command_declare.inc | clang -E -P -CC  -xc -I../include -DGENERATE_DOCS  - | sed -n '1,/DCE command documentation/!p' > c_api.h
+// cat ../include/generate/esp_modem_command_declare.inc | clang -E -P  -xc -I../include -DGENERATE_DOCS -DGENERATE_RST_LINKS - | sed 's/NL/\n/g' > cxx_api_links.rst
+
+// call parametrs by names for documentation
+
+
+//  --- DCE command documentation starts here ---
+
+class esp_modem::DCE: public DCE_T<GenericModule> {
+public:
+    using DCE_T<GenericModule>::DCE_T;
+
+
+
+
+
+
+
+/**
+ * @brief Sends the initial AT sequence to sync up with the device
+ * @return OK, FAIL or TIMEOUT
+ */ command_result sync (); /**
+ * @brief Reads the operator name
+ * @param[out] name module name
+ * @return OK, FAIL or TIMEOUT
+ */ command_result get_operator_name (std::string& name); /**
+ * @brief Stores current user profile
+ * @return OK, FAIL or TIMEOUT
+ */ command_result store_profile (); /**
+ * @brief Sets the supplied PIN code
+ * @param[in] pin Pin
+ * @return OK, FAIL or TIMEOUT
+ */command_result set_pin (const std::string& pin); /**
+ * @brief Checks if the SIM needs a PIN
+ * @param[out] pin_ok true if the SIM card doesn't need a PIN to unlock
+ * @return OK, FAIL or TIMEOUT
+ */ command_result read_pin (bool& pin_ok); /**
+ * @brief Sets echo mode
+ * @param[in] echo_on true if echo mode on (repeats the commands)
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_echo (const bool echo_on); /**
+ * @brief Sets the Txt or Pdu mode for SMS (only txt is supported)
+ * @param[in] txt true if txt mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result sms_txt_mode (const bool txt); /**
+ * @brief Sets the default (GSM) charater set
+ * @return OK, FAIL or TIMEOUT
+ */ command_result sms_character_set (); /**
+ * @brief Sends SMS message in txt mode
+ * @param[in] number Phone number to send the message to
+ * @param[in] message Text message to be sent
+ * @return OK, FAIL or TIMEOUT
+ */ command_result send_sms (const std::string& number, const std::string& message); /**
+ * @brief Resumes data mode (Switches back to th data mode, which was temporarily suspended)
+ * @return OK, FAIL or TIMEOUT
+ */ command_result resume_data_mode (); /**
+ * @brief Sets php context
+ * @param[in] x PdP context struct to setup modem cellular connection
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_pdp_context (PdpContext& x); /**
+ * @brief Switches to the command mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_command_mode (); /**
+ * @brief Switches to the CMUX mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_cmux (); /**
+ * @brief Reads the IMSI number
+ * @param[out] imsi Module's IMSI number
+ * @return OK, FAIL or TIMEOUT
+ */ command_result get_imsi (std::string& imsi); /**
+ * @brief Reads the IMEI number
+ * @param[out] imei Module's IMEI number
+ * @return OK, FAIL or TIMEOUT
+ */ command_result get_imei (std::string& imei); /**
+ * @brief Reads the module name
+ * @param[out] name module name
+ * @return OK, FAIL or TIMEOUT
+ */ command_result get_module_name (std::string& name); /**
+ * @brief Sets the modem to data mode
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_data_mode (); /**
+ * @brief Get Signal quality
+ * @param[out] rssi signal strength indication
+ * @param[out] ber channel bit error rate
+ * @return OK, FAIL or TIMEOUT
+ */ command_result get_signal_quality (int& rssi, int& ber); /**
+ * @brief Sets HW control flow
+ * @param[in] dce_flow 0=none, 2=RTS hw flow control of DCE
+ * @param[in] dte_flow 0=none, 2=CTS hw flow control of DTE
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_flow_control (int dce_flow, int dte_flow); /**
+ * @brief Hangs up current data call
+ * @return OK, FAIL or TIMEOUT
+ */ command_result hang_up (); /**
+ * @brief Get voltage levels of modem power up circuitry
+ * @param[out] voltage Current status in mV
+ * @param[out] bcs charge status (-1-Not available, 0-Not charging, 1-Charging, 2-Charging done)
+ * @param[out] bcl 1-100% battery capacity, -1-Not available
+ * @return OK, FAIL or TIMEOUT
+ */ command_result get_battery_status (int& voltage, int& bcs, int& bcl); /**
+ * @brief Power down the module
+ * @return OK, FAIL or TIMEOUT
+ */ command_result power_down (); /**
+ * @brief Reset the module
+ * @return OK, FAIL or TIMEOUT
+ */ command_result reset (); /**
+ * @brief Configures the baudrate
+ * @param[in] baud Desired baud rate of the DTE
+ * @return OK, FAIL or TIMEOUT
+ */ command_result set_baud (int baud);
+};

components/esp_modem/docs/generate_docs

@@ -0,0 +1,23 @@
+# Cleanup the generated html
+rm -rf html
+
+# Cleans example and test build dirs (to reduce the component size before upload)
+rm -rf ../examples/ap_to_pppos/build/ ../examples/simple_cmux_client/build/ ../examples/pppos_client/build/ ../examples/linux_modem/build/ ../examples/modem_console/build ../test/host_test/build/ ../test/target/build/
+
+# Generate C++ API header of the DCE
+cat ../include/generate/esp_modem_command_declare.inc | clang++ -E -P -CC  -xc++ -I../include -DGENERATE_DOCS  - | sed -n '1,/DCE command documentation/!p' > esp_modem_dce.hpp
+
+# Generate C API header of the modem_api.h
+cat ../include/generate/esp_modem_command_declare.inc | clang -E -P -CC  -xc -I../include -DGENERATE_DOCS  - | sed -n '1,/DCE command documentation/!p' > esp_modem_api_commands.h
+
+# RST with links to C++ API
+cat ../include/generate/esp_modem_command_declare.inc | clang -E -P  -xc -I../include -DGENERATE_DOCS -DGENERATE_RST_LINKS - | sed 's/NL/\n/g' > cxx_api_links.rst
+
+# Run doxygen
+doxygen
+
+# Generate the docs
+python -u -m sphinx.cmd.build -b html  . html
+
+# Cleanup the doxygen xml's
+rm -rf xml

components/esp_modem/docs/index.rst

@@ -0,0 +1,11 @@
+ESP-MODEM Programmers manual
+============================
+
+.. toctree::
+
+   Brief intro <README>
+   C interface <api_docs>
+   C++ interface <cxx_api_docs>
+   Advanced use cases <advanced_api>
+   Internal design <internal_design>
+   Internal implementation <internal_docs>

components/esp_modem/docs/internal_design.md

@@ -0,0 +1,36 @@
+# Internal design
+
+## Design decisions
+
+* Use C++ with additional C API
+
+* Use exceptions
+  - Use macro wrapper over `try-catch` blocks when exceptions off (use `abort()` if `THROW()`) 
+
+* Initializes and allocates in the constructor (might throw)
+  - easier code with exceptions ON, with exceptions OFF alloc/init failures are not treated as runtime error (program aborts)
+  - break down long initialization in constructor into more private methods
+
+* Implements different devices using inheritance from `GenericModule`, which is the most general implementation of a common modem
+  - Internally uses templates with device specialization (modeled as `DCE<SpecificModule>`) which could be used as well for some special cases, 
+  such as implantation of a minimal device (ModuleIf), add new AT commands (oOnly in compile time), or using the Module with DTE only (no DCE, no Netif) for sending AT commands without network
+  
+## DCE collaboration model
+
+The diagram describes how the DCE class collaborates with DTE, PPP and the device abstraction
+
+![DCE_architecture](DCE_DTE_collaboration.png)
+
+## Terminal inheritance
+
+Terminal is a class which can read or write data, and can handle callbacks when data are available. UART specialization
+is provided implementing these method using the uart driver.
+
+## CMUX terminal
+
+The below diagram depicts the idea of using CMUX terminal mode using the CMuxInstance class which is a terminal
+(it implements the basic read/write methods) interfacing arbitrary number of virtual terminals,
+but at the same time it is also composed of CMux class, which consumes the original terminal and uses its read/write methods
+to multiplex the terminal.
+
+![CMUX Terminal](CMux_collaboration.png)

components/esp_modem/docs/internal_docs.rst

@@ -0,0 +1,85 @@
+DCE Internal implementation
+===========================
+
+This chapter provides a detailed description of the classes and building blocks of the esp-modem component and their responsibilities.
+
+The esp-modem actually implements the DCE class, which in turn aggregates these thee units:
+
+- :ref:`DTE<dte_impl>` to communicate with the device on a specific Terminal interface such as UART.
+- :ref:`Netif<netif_impl>` to provide the network connectivity
+- :ref:`Module<module_impl>` to define the specific command library
+
+------------
+
+.. doxygengroup:: ESP_MODEM_DCE
+   :members:
+
+.. _dte_impl:
+
+DTE abstraction
+---------------
+
+DTE is a basic unit to talk to the module using a Terminal interface. It also implements and uses the CMUX to multiplex
+terminals. Besides the DTE documentation, this section also refers to the
+
+- :ref:`Terminal interface<term_impl>`
+- :ref:`CMUX implementation<cmux_impl>`
+
+
+------------
+
+.. doxygengroup:: ESP_MODEM_DTE
+   :members:
+
+.. _term_impl:
+
+Terminal interface
+^^^^^^^^^^^^^^^^^^
+
+.. doxygengroup:: ESP_MODEM_TERMINAL
+   :members:
+
+.. _cmux_impl:
+
+CMUX implementation
+^^^^^^^^^^^^^^^^^^^
+
+.. doxygengroup:: ESP_MODEM_CMUX
+   :members:
+
+.. _netif_impl:
+
+Netif
+-----
+
+.. doxygengroup:: ESP_MODEM_NETIF
+   :members:
+
+.. _module_impl:
+
+Module abstraction
+------------------
+
+.. doxygengroup:: ESP_MODEM_MODULE
+   :members:
+
+Command library
+^^^^^^^^^^^^^^^
+
+This is a namespace holding a library of typical AT commands used by supported devices.
+Please refer to the :ref:`c_api` for the list of supported commands.
+
+.. doxygengroup:: ESP_MODEM_DCE_COMMAND
+   :members:
+
+
+Modem types
+-----------
+
+.. doxygengroup:: ESP_MODEM_TYPES
+   :members:
+
+
+
+
+