Issues with running FOTA and cJSON

[simon belanger]

Hi,

I recently added FOTA support on my project which runs on nRF5340 + nRF7002. I am currently working on a devboard, nRF7002DK.

Previously, I was running the project on NCS 2.7.0 and I was using the cJSON library to generate the payloads for my MQTT messages. When adding FOTA support to the project, I migrated to NCS 2.9.0 to facilitate the switch to sysbuild, which allowed be to embed MCUBoot as the bootloader. I implemented FOTA using the FOTA download library.

However, I am now having issues with the MQTT payload that I send periodically. Whenever a payload is sent, which is formatted in JSON using cJSON library, I know I will be unable to perform an FOTA update if I do not reboot first. My first guess would be memory management but I am not sure about it.

The error I get from the FOTA download is as such : 

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[00:00:26.841,094] <inf> mqtt: topic received gateway/update/0011ce

[00:00:26.841,156] <inf> mqtt: Received: https://to-delete-testing.s3.ca-central-1.amazonaws.com/zephyr.signed.bin

[00:00:26.841,186] <inf> main: Update queried

[00:00:26.841,186] <inf> ota: https://bucket.s3.ca-central-1.amazonaws.com/zephyr.signed.bin

[00:00:26.841,247] <inf> ota: host : bucket.s3.ca-central-1.amazonaws.com

[00:00:26.841,918] <inf> ota: file : zephyr.signed.bin

[00:00:26.844,512] <inf> mqtt: Deiniting MQTT

[00:00:26.844,543] <inf> mqtt: Disconnecting MQTT client

[00:00:26.846,221] <inf> mqtt: MQTT client disconnected: 0

[00:00:26.846,252] <inf> mqtt: mqtt thread suspended

[00:00:26.846,252] <inf> ota: Mqtt was closed. Starting FOTA

[00:00:26.846,313] <inf> ota: FOTA inited

[00:00:26.846,405] <inf> download_client: Downloading: zephyr.signed.bin [0]

[00:00:26.846,405] <inf> ota: FOTA started

[00:00:26.973,480] <err> download_client: DNS lookup failed bucket.s3.ca-central-1.amazonaws.com

[00:00:26.973,510] <err> fota_download: Download client error

[00:00:26.973,510] <inf> ota: Received error from fota_download, 2

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

[00:00:26.841,094] <inf> mqtt: topic received gateway/update/0011ce
[00:00:26.841,156] <inf> mqtt: Received: https://to-delete-testing.s3.ca-central-1.amazonaws.com/zephyr.signed.bin
[00:00:26.841,186] <inf> main: Update queried
[00:00:26.841,186] <inf> ota: https://bucket.s3.ca-central-1.amazonaws.com/zephyr.signed.bin
[00:00:26.841,247] <inf> ota: host : bucket.s3.ca-central-1.amazonaws.com
[00:00:26.841,918] <inf> ota: file : zephyr.signed.bin
[00:00:26.844,512] <inf> mqtt:  Deiniting MQTT
[00:00:26.844,543] <inf> mqtt: Disconnecting MQTT client
[00:00:26.846,221] <inf> mqtt: MQTT client disconnected: 0
[00:00:26.846,252] <inf> mqtt: mqtt thread suspended
[00:00:26.846,252] <inf> ota: Mqtt was closed. Starting FOTA
[00:00:26.846,313] <inf> ota: FOTA inited
[00:00:26.846,405] <inf> download_client: Downloading: zephyr.signed.bin [0]
[00:00:26.846,405] <inf> ota: FOTA started
[00:00:26.973,480] <err> download_client: DNS lookup failed bucket.s3.ca-central-1.amazonaws.com
[00:00:26.973,510] <err> fota_download: Download client error
[00:00:26.973,510] <inf> ota: Received error from fota_download, 2

However, when I do not use the cJSON library prior to starting the update, it works flawlessly.

I was wondering if there are know changes I should know about between versions 2.7.0 and 2.9.0 of NCS whcich affect the way I should configure my project. My configuration file is a such

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CONFIG_GPIO=n

## To remove on production version

# Printing to UART

CONFIG_SERIAL=n

# Logging

CONFIG_LOG=n

# Wi-Fi

CONFIG_WIFI=y

CONFIG_NRF70_SR_COEX=y

CONFIG_NRF70_SR_COEX_RF_SWITCH=y

# WPA supplicant

CONFIG_WIFI_NM_WPA_SUPPLICANT=y

CONFIG_WIFI_NM_WPA_SUPPLICANT_LOG_LEVEL_OFF=y

CONFIG_NRF70_RX_NUM_BUFS=16

CONFIG_NRF70_MAX_TX_AGGREGATION=4

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

CONFIG_GPIO=n

## To remove on production version
# Printing to UART
CONFIG_SERIAL=n
# Logging
CONFIG_LOG=n

# Wi-Fi
CONFIG_WIFI=y
CONFIG_NRF70_SR_COEX=y
CONFIG_NRF70_SR_COEX_RF_SWITCH=y

# WPA supplicant
CONFIG_WIFI_NM_WPA_SUPPLICANT=y
CONFIG_WIFI_NM_WPA_SUPPLICANT_LOG_LEVEL_OFF=y

CONFIG_NRF70_RX_NUM_BUFS=16
CONFIG_NRF70_MAX_TX_AGGREGATION=4


# Wi-Fi credentials
CONFIG_WIFI_CREDENTIALS=y
CONFIG_WIFI_CREDENTIALS_STATIC=n

# Networking Management API
CONFIG_NET_MGMT=y
CONFIG_NET_MGMT_EVENT=y
CONFIG_NET_MGMT_EVENT_INFO=y
CONFIG_NET_MGMT_EVENT_STACK_SIZE=5120
CONFIG_NET_CONNECTION_MANAGER=y
CONFIG_L2_WIFI_CONNECTIVITY=y
CONFIG_NET_CONNECTION_MANAGER_MONITOR_STACK_SIZE=5200
CONFIG_WIFI_MGMT_EXT=y
#CONFIG_WIFI_MGMT_AP_STA_INACTIVITY_TIMEOUT=0
#CONFIG_BSS_MAX_IDLE_TIME=0

# Support for shell commands
#CONFIG_SHELL=y
#CONFIG_WIFI_CREDENTIALS_SHELL=y
#CONFIG_SHELL_STACK_SIZE=4400

# DK library
CONFIG_DK_LIBRARY=y

# System settings
CONFIG_NEWLIB_LIBC=y
CONFIG_NEWLIB_LIBC_NANO=n
CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y
CONFIG_CJSON_LIB=y

# Networking
CONFIG_NETWORKING=y
CONFIG_NET_NATIVE=y
CONFIG_NET_SOCKETS=y
CONFIG_NET_SOCKETS_POSIX_NAMES=y
CONFIG_POSIX_MAX_FDS=16

CONFIG_NET_L2_ETHERNET=y
CONFIG_NET_IPV6=y
CONFIG_NET_IPV4=y
CONFIG_NET_TCP=y
CONFIG_NET_DHCPV4=y
CONFIG_DNS_RESOLVER=y

# Memory
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=8192
CONFIG_MAIN_STACK_SIZE=5200
CONFIG_HEAP_MEM_POOL_SIZE=153600
#CONFIG_HEAP_MEM_POOL_IGNORE_MIN=y

CONFIG_NET_TCP_WORKQ_STACK_SIZE=2048
CONFIG_NET_TX_STACK_SIZE=4096
CONFIG_NET_RX_STACK_SIZE=4096
CONFIG_NET_BUF_RX_COUNT=16
CONFIG_NET_BUF_TX_COUNT=16
CONFIG_NET_BUF_DATA_SIZE=256
CONFIG_NET_TC_TX_COUNT=0

# MQTT
CONFIG_MQTT_LIB=y
CONFIG_MQTT_CLEAN_SESSION=y
CONFIG_MQTT_LIB_TLS=y  # Enable TLS for the MQTT library

# STEP 1.5 - Increase the MQTT keep alive time (seconds)
CONFIG_MQTT_KEEPALIVE=240

CONFIG_MQTT_BROKER_HOSTNAME="iot.elia.one"
CONFIG_MQTT_BROKER_PORT=8883

# TLS
# STEP 1.3 - Enable the TLS library and security relevant configurations
CONFIG_NET_SOCKETS_SOCKOPT_TLS=y
CONFIG_TLS_CREDENTIALS=y
CONFIG_MBEDTLS_RSA_C=y

# mbedTLS
CONFIG_NRF_SECURITY=y
CONFIG_MBEDTLS=y
CONFIG_MBEDTLS_ENABLE_HEAP=y
CONFIG_MBEDTLS_HEAP_SIZE=81920
CONFIG_PSA_WANT_KEY_TYPE_RSA_PUBLIC_KEY=y
CONFIG_PSA_WANT_RSA_KEY_SIZE_2048=y
#CONFIG_MBEDTLS_RSA_C=y
CONFIG_MBEDTLS_TLS_LIBRARY=y

# Certificates storage
CONFIG_FLASH=y
CONFIG_FLASH_MAP=y

CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_LITTLEFS=y

# External Flash SPI NOR
CONFIG_GPIO=y
CONFIG_SPI=y
CONFIG_SPI_NOR=y
CONFIG_SPI_NOR_SFDP_DEVICETREE=y
CONFIG_SPI_NOR_FLASH_LAYOUT_PAGE_SIZE=4096
# QSPI drivers are enabled by default for some chips.
# Disable it explicitly to be sure QSPI is disabled.
CONFIG_NORDIC_QSPI_NOR=n 

# Misc
CONFIG_REBOOT=y
CONFIG_ADC=y #for battery monitoring
CONFIG_SYS_HEAP_RUNTIME_STATS=y

# FOTA
# FOTA library
CONFIG_FOTA_DOWNLOAD=y

# Download client
CONFIG_DOWNLOAD_CLIENT=y
CONFIG_DOWNLOAD_CLIENT_STACK_SIZE=4096

# DFU Target
CONFIG_DFU_TARGET=y

# Image manager
CONFIG_IMG_MANAGER=y
CONFIG_FLASH=y
CONFIG_FLASH_MAP=y
CONFIG_STREAM_FLASH=y
CONFIG_IMG_ERASE_PROGRESSIVELY=y

# Application Upgrade support
CONFIG_BOOTLOADER_MCUBOOT=y

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# Network

CONFIG_NET_L2_WIFI_MGMT=y

CONFIG_NANOPB=y

# Memory

CONFIG_NET_MGMT_EVENT_STACK_SIZE=5120

CONFIG_NET_MGMT_EVENT_QUEUE_TIMEOUT=5000

# Bluetooth LE

CONFIG_BT=y

CONFIG_BT_PERIPHERAL=y

CONFIG_BT_PERIPHERAL_PREF_TIMEOUT=75

CONFIG_BT_WIFI_PROV=y

CONFIG_BT_BONDABLE=n

#CONFIG_BT_DEBUG_LOG=y

CONFIG_BT_SMP=y

CONFIG_BT_BUF_ACL_RX_SIZE=151

CONFIG_BT_L2CAP_TX_MTU=147

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

# Network
CONFIG_NET_L2_WIFI_MGMT=y

CONFIG_NANOPB=y

# Memory
CONFIG_NET_MGMT_EVENT_STACK_SIZE=5120

CONFIG_NET_MGMT_EVENT_QUEUE_TIMEOUT=5000

# Bluetooth LE
CONFIG_BT=y
CONFIG_BT_PERIPHERAL=y
CONFIG_BT_PERIPHERAL_PREF_TIMEOUT=75
CONFIG_BT_WIFI_PROV=y
CONFIG_BT_BONDABLE=n

#CONFIG_BT_DEBUG_LOG=y
CONFIG_BT_SMP=y
CONFIG_BT_BUF_ACL_RX_SIZE=151
CONFIG_BT_L2CAP_TX_MTU=147
CONFIG_BT_BUF_ACL_TX_SIZE=151
CONFIG_BT_RX_STACK_SIZE=5120
CONFIG_BT_DEVICE_NAME_DYNAMIC=y

# Storing credentials
# STEP 1.2 - Enable the necessary NVS and flash configurations
CONFIG_FLASH=y
CONFIG_FLASH_PAGE_LAYOUT=y
CONFIG_FLASH_MAP=y

CONFIG_NVS=y
CONFIG_SETTINGS=y
CONFIG_SETTINGS_NVS=y

# STEP 1.3 - Enable the necessary Wi-Fi credential configurations
CONFIG_WIFI_CREDENTIALS=y
CONFIG_WIFI_CREDENTIALS_MAX_ENTRIES=1
CONFIG_WIFI_CREDENTIALS_BLE=y

# Support for shell commands
CONFIG_SHELL=n
CONFIG_WIFI_CREDENTIALS_SHELL=n
#CONFIG_SHELL_STACK_SIZE=4400

# Fixes bug where some devices would have trouble connecting 
CONFIG_BT_AUTO_PHY_UPDATE=n

and here is an excerpt of the app code that uses the cJSON library

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void device_publish_status(void) {

int err;

char *json_payload = NULL;

cJSON *response = NULL;

// Root section

if ((response = cJSON_CreateObject()) == NULL) {

goto end;

}

if (cJSON_AddStringToObject(response, "device_id", device_id) == NULL) {

goto end;

}

if (cJSON_AddStringToObject(response, "device_type", "room-lp") == NULL) {

goto end;

}

if (cJSON_AddStringToObject(response, "topic", MQTT_TOPIC_STR[TOPIC_GATEWAY_STATUS]) == NULL) {

goto end;

}

if (cJSON_AddNumberToObject(response, "uptime_mins", k_uptime_seconds()/60) == NULL) {

goto end;

}

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

void device_publish_status(void) {
    int err;
    char *json_payload = NULL;
    cJSON *response = NULL;

    // Root section
    if ((response = cJSON_CreateObject()) == NULL) {
        goto end;
    }
    if (cJSON_AddStringToObject(response, "device_id", device_id) == NULL) {
        goto end;
    }
    if (cJSON_AddStringToObject(response, "device_type", "room-lp") == NULL) {
        goto end;
    }
    if (cJSON_AddStringToObject(response, "topic", MQTT_TOPIC_STR[TOPIC_GATEWAY_STATUS]) == NULL) {
        goto end;
    }
    if (cJSON_AddNumberToObject(response, "uptime_mins", k_uptime_seconds()/60) == NULL) {
        goto end;
    }
    if (cJSON_AddNumberToObject(response, "mqtt_uptime_mins", mqtt_uptime()/60) == NULL) {
        goto end;
    }
    if (cJSON_AddNumberToObject(response, "net_uptime_mins", net_uptime_seconds()/60) == NULL) {
        goto end;
    }
    int battery_voltage_mv = 0;
    if ((err = battery_monitor_read_battery_voltage(&battery_voltage_mv)) != 0) {
        //LOG_ERR("Failed to read battery voltage : %d", err);
    }
    if (cJSON_AddNumberToObject(response, "battery_voltage_mv", battery_voltage_mv) == NULL) {
        //goto end;
    }

    // App section
    cJSON *app = NULL;
    if ((app = cJSON_CreateObject()) == NULL) {
        goto end;
    }
    if (cJSON_AddStringToObject(app, "version", TOSTRING(APP_BUILD_VERSION)) == NULL) {
        goto end;
    }
    if (cJSON_AddStringToObject(app, "time", __TIME__) == NULL) {
        goto end;
    }
    if (cJSON_AddStringToObject(app, "date", __DATE__) == NULL) {
        goto end;
    }
    if (cJSON_AddItemToObject(response, "app", app) == NULL) {
        goto end;
    }

    // Network status
    cJSON *net;
    if ((net = network_serialize_wifi_iface_status()) == NULL) {
        //goto end;
    }
    if (cJSON_AddItemToObject(response, "wifi_status", net) == NULL) {
        goto end;
    }

    //PS config
    cJSON* ps_status;
    if ((ps_status = network_serialize_wifi_ps_status()) == NULL) {
        goto end;
    }
    if (cJSON_AddItemToObject(response, "ps_status", ps_status) == NULL) {
        //goto end;
    }
   
    if ((json_payload = cJSON_Print(response)) == NULL) {
        LOG_ERR("Failed to format response to JSON.");
        goto end;
    }

    // send payload to response topic
    if ((err = publish_to_topic(TOPIC_GATEWAY_STATUS_RESPONSE, json_payload, strlen(json_payload))) != 0) {
        LOG_ERR("Failed to send message, %d", err);
    }
    cJSON_FreeString(json_payload);
end:
    cJSON_Delete(response);
    return;
}