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How to: LTE v2

This article will demonstrate how to upgrade existing CHESTER firmware to the LTE v2 and Cloud v2.

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LTE v2 is currently in the separate lte-v2 branch on GitLab. We are currently working on merging it to the mainline soon.

LTE v2 is using a newer UDP protocol that supports downlink messages and automatically handles fragmentation, confirmation and signing of the packets with SHA-256.

Downlink messages or configuration messages can be sent by API or in the HARDWARIO Cloud v2 user interface.

Configuration messages app config ... can be send to any device using LTE v2. There is no need to add anything to your application, the ctr_cloud subsystem takes care of all.

CHESTER LTE v2 Firmware Examples​

Demo​

Simple example where you need just a CHESTER-M mainboard and you can uplink data and downlink commands to change LED or change configuration.

After you flash LTE modem to v1.7.0 or higer, you can flash APP/BLE MCU with CHESTER Demo with HARDWARIO CLI by typing:

hardwario chester app flash af637aa1c5b842c18f9b10b070cb0292

https://gitlab.hardwario.com/chester/sdk/-/tree/lte-v2/applications/demo

CHESTER Control​

This is an improved CHESTER Input application.

After you flash LTE modem to v1.7.0 or higer, you can flash APP/BLE MCU with CHESTER Control with HARDWARIO CLI by typing:

hardwario chester app flash a1201384db424cb394b5e9130293f708

https://gitlab.hardwario.com/chester/sdk/-/tree/martin/control

  • Added reconfigurable inputs - you can reconfigure any of the 4 inputs to measure voltage, current, count pulses or react to logic level change.
  • Adds a control option with CHESTER-X4 in slot B for switching 4 outputs that are powered from the external DC power supply.

The project also contains example scripts on how to send downlink configuration and messages with curl.

CHESTER Control also contains configuration definitions through macros. So you define config parameters only in app_config.h file and settings, shell, and help commands are generated with macros.

Changes for LTE v2​

Flash LTE Modem Firmware​

You need to update the LTE modem to the v1.7.0 or higher. This firmware is not backward compatible with v1.3.0 that is only for older LTE v1.

Follow the LTE Modem over J-Link article and download firmware v1.7.0.

Use lte-v2 Branch​

Until all is merged in the master. You have to use lte-v2 branch in the chester subfolder. You can also do it by adding revision in your west.yml file:

projects:
  - name: sdk.git
    remote: hardwario-chester
    revision: lte-v2
    path: chester
    import: true

Project Configuration​

In file prj.conf add CONFIG_CTR_CLOUD=y.

In file CMakeLists.txt change shield from ctr_lte to ctr_lte_v2.

Decoders and Encoders​

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Please use Demo and CHESTER Control projects as an example of how new codec files look.

In the codec folder update cbor-decoder.yaml, and optionally create cbor-encoder.yaml

Encoder and decoder .yaml files now have these changes:

  • Added a header.
  • It is fully hierarchical now. You have to define the complete tree that will then become JSON.
  • Modificators like div, fpp, key, tso,... now have $ prefix.

YAML files are generated to the C .h file by using command west gen-codec run from your application folder (where your run west build).

Instead of msg_key.h, now the YAML is generated to the src/app_codec.h file.

Update your app_cbor.c to the new hierarchival definitions. Each level is divided by double underscores, for example, CODEC_KEY_E_NETWORK__PARAMETER__EEST. Also don't forget to include a new header file #include "app_codec.h".

Initialization​

With LTE v2 we've added another layer ctr_cloud that you use instead of ctr_lte.

In the file app_init.c add #include <chester/ctr_cloud.h> and use ctr_cloud_init() instead of ctr_lte_start().

Optionally you can:

  • Call ctr_cloud_set_callback() to set callback for the downlink messages
  • Set polling interval by ctr_cloud_set_pull_interval() which defines how often CHESTER automatically asks Cloud for queued downlink messages.
  • Use ctr_cloud_wait_initialized(K_FOREVER) that will stop the main task until the cloud connection is established and all codecs and configuration is sent.

Send Data​

Instead of ctr_lte_send() now call ctr_cloud_send(). Include new #include <chester/ctr_cloud.h>

In the Demo project, we also removed app_send.c file, because it only created a new worker without really needing one. Sending is now in app_work.c.

Function ctr_cloud_send() now is blocking, so the return code tells you whether the data was sent successfully or not. No callback is needed now, which also added another asynchronous complexity.

IP and Port​

For Vodafone SIM cards, use APN hardwario, IP 192.168.192.4 and port 5002. Don't use the previous hardwario.com APN name.

For the other carriers, the data goes through the public internet, you have to set the server's public IP 20.101.123.47 and port is the same 5002.