Sigfox End-Point library (EP_LIB)

Description

The Sigfox End-Point Library is a public example of the Sigfox radio protocol implementation. This is the official open source successor of the old library delivered by Sigfox (versions up to v2.11.0). It provides the middleware to build Sigfox frames and schedule the transmission or reception appropriately.

Most of Sigfox features are implemented:

• Application messages (uplink and optional downlink procedures).
• Control keep alive message.
• Single or multi radio configurations support (individually selectable RCx).
• Single or multi frames per message (N=1, 2 or 3).
• 100 bps and/or 600 bps uplink bitrates support.
• Fixed or dynamic uplink payload size.
• Public key switch.
• Configurable message counter rollover.

This new library has a clear differentiator in term of memory optimization: thanks to a very modular architecture and multiple compilation flags, the code can be optimized to match any device application. The library is designed to operate either in blocking or asynchronous mode, and supports most of MCUs and radio chipsets.

Technical links

• Sigfox End-Point library wiki : please visit the wiki to read more documentation and get started with examples.
• Sigfox 0G technology discussion space : do not hesitate to use this space if you find any bug or want to share a common interest improvement.
• Sigfox device radio specification : this is the input specification of the Sigfox End-Point library, implemented in C langage for embedded device projects. For a better comprehension the code uses the same names and acronyms as the document.

Stack architecture

Compilation flags for optimization

Most of Sigfox radio parameters and features are conditioned to a dedicated flag, so that the stack can be configured to perfectly match your application, without dead code and thus with a minimum memory footprint. The flags are located in the sigfox_ep_flags.h file, but can also be set through the cmake command when building the project (see section How to add Sigfox library to your project).

To have such a flexibility, the stack uses a lot of preprocessor directives, which makes the source code less readable. If you plan to look or modify the source files, we advise you to run the cmake pre-compilation command, that will remove all preprocessor directives according to your flags selection (see section Precompiled source code).

Below is the list of available flags.

Flag name	Value	Description
RCx_ZONE	undefined / defined	Support the RCx radio configuration if defined.
APPLICATION_MESSAGES	undefined / defined	Support uplink application messages if defined.
CONTROL_KEEP_ALIVE_MESSAGE	undefined / defined	Support uplink control keep alive message if defined.
BIDIRECTIONAL	undefined / defined	Support bidirectional procedure (downlink) if defined. Only applicable to application messages. Otherwise all messages will be uplink only.
ASYNCHRONOUS	undefined / defined	Asynchronous mode if defined, blocking mode otherwise.
LOW_LEVEL_OPEN_CLOSE	undefined / defined	Enable MCU and RF open/close functions if defined.
REGULATORY	undefined / defined	Enable radio regulatory control (DC, FH or LBT check) if defined.
LATENCY_COMPENSATION	undefined / defined	Enable radio latency compensation to improve MCU timers accuracy.
SINGLE_FRAME	undefined / defined	Send 1 frame per message (N=1) if defined. Otherwise number of frames per message is dynamically given when sending a message (N=1, 2 or 3).
UL_BIT_RATE_BPS	undefined / 100 / 600	If defined, give the only uplink bit rate supported (100bps or 600bps depending on the RC). Otherwise, value is dynamically given when sending a message.
TX_POWER_DBM_EIRP	undefined / <tx_power_dbm_eirp>	If defined, give the only TX power supported by the radio. Otherwise the value is dynamically given when sending a message.
T_IFU_MS	undefined / <t_ifu_ms>	If defined, give the fixed inter-frame delay used between uplink frames of a same message (0 to 2000ms). Value 0 disables the delay and associated timers to optimize memory space. Otherwise value is dynamically given when sending a message.
T_CONF_MS	undefined / <t_conf_ms>	If defined, give the fixed delay between downlink frame reception and uplink confirmation message (1400 to 4000ms). Otherwise value is dynamically given when sending a message.
UL_PAYLOAD_SIZE	undefined / <ul_payload_size>	If defined, give the only uplink payload length supported (0 to 12). Value 0 enables the bit 0, bit 1 and empty messages. Otherwise, all uplink payload lengths are dynamically supported.
CRC_HW	undefined / defined	If defined, enable hardware CRC through MCU API functions. Otherwise the embedded driver is used.
MESSAGE_COUNTER_ROLLOVER	undefined / 128 / 256 / 512 / 1024 / 2048 / 4096	If defined, give the only message counter rollover value supported. Otherwise, value is dynamically given when opening the library.
PARAMETERS_CHECK	undefined / defined	Enable parameters check if defined.
CERTIFICATION	undefined / defined	Enable certification features if defined.
PUBLIC_KEY_CAPABLE	undefined / defined	Enable public key switch feature if defined.
VERBOSE	undefined / defined	Enable credentials (ID / PAC) API access and version control functions if defined.
ERROR_CODES	undefined / defined	Use return codes if defined, otherwise all functions return void.
ERROR_STACK	undefined / <error_stack_depth>	If defined, store low level errors in a stack (the macro gives the depth). Errors can be read with the SIGFOX_EP_API_unstack_error() function.

How to add Sigfox library to your project

Submodule

The best way to embed the Sigfox End-Point library into your project is to use a Git submodule. The library will be seen as a sub-repository with independant history. It will be much easier to upgrade the library or to switch between versions when necessary, by using the common git pull and git checkout commands within the sigfox-ep-lib folder.

In order to keep the repository clean, it is recommended to select the compilation flags in your project settings, without modifying the sigfox_ep_flags.h file (which is only included if the USE_SIGFOX_EP_FLAGS_H flag is defined). This way, you can change the compilation flags when you want, in order to add features or save code memory. The source code will be set up automatically according to your flags selection, without any action or diff in the submodule folder. You will also need to exclude the src/manuf folder from build (where the manufacturer templates are defined) and implement the functions in another location of your project, so that the repository is kept clean.

To add the Sigfox library submodule, go to your project location and run the following commands:

mkdir lib
cd lib/
git submodule add https://github.com/sigfox-tech-radio/sigfox-ep-lib.git

This will clone the Sigfox End-Point library repository. At project level, you can commit the submodule creation with the following commands:

git commit --message "Add Sigfox End Point library submodule."
git push

With the submodule, you can easily:

• Update the library to the latest version:

cd lib/sigfox-ep-lib/
git pull
git checkout master

• Use a specific release:

cd lib/sigfox-ep-lib/
git pull
git checkout <tag>

Raw source code

You can download or clone any release of the Sigfox End-Point library and copy all files into your project. Then you can either define the USE_SIGFOX_EP_FLAGS_H flag and select your compilation flags in the sigfox_ep_flags.h file, or define them in your project settings.

git clone https://github.com/sigfox-tech-radio/sigfox-ep-lib.git

Precompiled source code

You can download or clone any release of the Sigfox End-Point library and copy all files into your project. If you do not plan to change your compilation flags in the future, you can perform a precompilation step before copying the file in your project. The precompilation will remove all preprocessor directives according to your flags selection, in order to produce a more readable code. Then you can copy the new files into your project.

git clone https://github.com/sigfox-tech-radio/sigfox-ep-lib.git

To perform the precompilation, you have to install cmake and unifdef tools, and run the following commands:

cd sigfox-ep-lib/
mkdir build
cd build/

• Precompiling by reading the sigfox_ep_flags.h file:

cmake -DUSE_SIGFOX_EP_FLAGS_H=ON ..
make precompil

• Precompiling by entering the flags selection on command line:

cmake -DUSE_SIGFOX_EP_FLAGS_H=OFF \
      -DRC1_ZONE=ON \
      -DRC2_ZONE=ON \
      -DRC3C_ZONE=ON \
      -DRC3D_ZONE=ON \
      -DRC4_ZONE=ON \
      -DRC5_ZONE=ON \
      -DRC6_ZONE=ON \
      -DRC7_ZONE=ON \
      -DAPPLICATION_MESSAGES=ON \
      -DCONTROL_KEEP_ALIVE_MESSAGE=ON \
      -DBIDIRECTIONAL=ON \
      -DASYNCHRONOUS=ON \
      -DLOW_LEVEL_OPEN_CLOSE=ON \
      -DREGULATORY=ON \
      -DLATENCY_COMPENSATION=ON \
      -DSINGLE_FRAME=ON \
      -DPARAMETERS_CHECK=ON \
      -DCERTIFICATION=ON \
      -DPUBLIC_KEY_CAPABLE=ON \
      -DVERBOSE=ON \
      -DCRC_HW=OFF \
      -DERROR_CODES=ON \
      -DUL_BIT_RATE_BPS=OFF \
      -DT_IFU_MS=OFF \
      -DT_CONF_MS=OFF \
      -DUL_PAYLOAD_SIZE=OFF \
      -DMESSAGE_COUNTER_ROLLOVER=OFF \
      -DERROR_STACK=12 ..
make precompil

The new files will be generated in the build/precompil folder.

Static library

You can also download or clone any release of the Sigfox End-Point library and build a static library.

git clone https://github.com/sigfox-tech-radio/sigfox-ep-lib.git

To build a static library, you have to install cmake tool and run the following commands:

cd sigfox-ep-lib/
mkdir build
cd build/

• Building by reading the sigfox_ep_flags.h file:

cmake -DUSE_SIGFOX_EP_FLAGS_H=ON ..
make sigfox_ep_lib

• Building by entering the flags selection on command line:

cmake -DUSE_SIGFOX_EP_FLAGS_H=OFF \
      -DRC1_ZONE=ON \
      -DRC2_ZONE=ON \
      -DRC3C_ZONE=ON \
      -DRC3D_ZONE=ON \
      -DRC4_ZONE=ON \
      -DRC5_ZONE=ON \
      -DRC6_ZONE=ON \
      -DRC7_ZONE=ON \
      -DAPPLICATION_MESSAGES=ON \
      -DCONTROL_KEEP_ALIVE_MESSAGE=ON \
      -DBIDIRECTIONAL=ON \
      -DASYNCHRONOUS=ON \
      -DLOW_LEVEL_OPEN_CLOSE=ON \
      -DREGULATORY=ON \
      -DLATENCY_COMPENSATION=ON \
      -DSINGLE_FRAME=ON \
      -DPARAMETERS_CHECK=ON \
      -DCERTIFICATION=ON \
      -DPUBLIC_KEY_CAPABLE=ON \
      -DVERBOSE=ON \
      -DCRC_HW=OFF \
      -DERROR_CODES=ON \
      -DUL_BIT_RATE_BPS=OFF \
      -DT_IFU_MS=OFF \
      -DT_CONF_MS=OFF \
      -DUL_PAYLOAD_SIZE=OFF \
      -DMESSAGE_COUNTER_ROLLOVER=OFF \
      -DERROR_STACK=12 ..
make sigfox_ep_lib

The archive will be generated in the build/lib folder.

Addons

RF & Protocol

In order to test your implementation against Sigfox specifications, you can use the Sigfox End-Point RF & Protocol addon which will drive the library to perform Sigfox test modes.

The addon can be directly generated from the Sigfox End-Point library cmake by using the ADDON_RFP option:

cmake <all previous flags> -DADDON_RFP=ON ..
make precompil_sigfox_ep_addon_rfp
make sigfox_ep_addon_rfp

Type Approval

In order to pass radio regulatory certifications on your device, you can use the Sigfox End-Point Type Approval addon which will drive the library to perform regulatory test modes.

The addon can be directly generated from the Sigfox End-Point library cmake by using the ADDON_TA option:

cmake <all previous flags> -DADDON_TA=ON ..
make precompil_sigfox_ep_addon_ta
make sigfox_ep_addon_ta

RF API implementation examples

In this organization you will find some example of RF_APIimplementation

ST S2LP

The S2LP RF API example code can be directly generated from the Sigfox End-Point library cmake by using the S2LP_RF_API option:

cmake <all previous flags> -DS2LP_RF_API=ON ..
make precompil_s2lp_rf_api
make s2lp_rf_api

Semtech LR11XX

The LR11XX RF API example code can be directly generated from the Sigfox End-Point library cmake by using the LR11XX_RF_API option:

cmake <all previous flags> -DLR11XX_RF_API=ON ..
make precompil_lr11xx_rf_api
make lr11xx_rf_api

Semtech SX126X

The SX126X RF API example code can be directly generated from the Sigfox End-Point library cmake by using the SX126X_RF_API option:

cmake <all previous flags> -DSX126X_RF_API=ON ..
make precompil_sx126x_rf_api
make sx126x_rf_api