Nordic Thingy:91

Configs

wakaama

Wakaama LwM2M demo using descriptors/examples/thingy91_wakaama_lte.yaml. Brings up LTE, registers with the public Eclipse Leshan sandbox, and exposes the on-board sensors as LwM2M objects:

Sensor

Reading

LwM2M

uorb topic

BME680

Temperature

3303/0/5700

sensor_ambient_temp0

BME680

Humidity

3304/0/5700

sensor_humi0

BME680

Pressure

3315/0/5700

sensor_baro0

BME680

Gas

3300/0/5700

sensor_gas0

BH1749

Colour R

33001/0/0

sensor_rgb0

BH1749

Colour G

33001/0/1

sensor_rgb0

BH1749

Colour B

33001/0/2

sensor_rgb0

Lightwell

Colour (rw)

33002/0/0

rgbled0

Sense LED

Colour (rw)

33003/0/0

rgbled1

GNSS

Latitude

6/0/0

sensor_gnss0

GNSS

Longitude

6/0/1

sensor_gnss0

GNSS

Altitude

6/0/2

sensor_gnss0

GNSS

Radius/eph

6/0/3

sensor_gnss0

GNSS

Time (UTC)

6/0/5

sensor_gnss0

GNSS

Speed

6/0/6

sensor_gnss0

GNSS

Satellites

33005/0/0

sensor_gnss0

GNSS

Course

33005/0/1

sensor_gnss0

GNSS

Accuracy V

33005/0/2

sensor_gnss0

GNSS

HDOP

33005/0/3

sensor_gnss0

GNSS

PDOP

33005/0/4

sensor_gnss0

GNSS

VDOP

33005/0/5

sensor_gnss0

Notes:

  • Runs non-secure behind the dedicated Thingy:91 miniboot_s bootloader, which grants I2C2 to the non-secure app (CONFIG_NRF91_SERIAL2_NS) and the RGB-LED PWMs (CONFIG_NRF91_PWM0_NS, CONFIG_NRF91_PWM1_NS).

  • The BH1749 and both RGB LEDs are on the 3.3 V rail; nrf91_pmic.c enables the ADP5360 buck-boost at bring-up (off at power-on reset). BME680 is on 1.8 V.

  • The board has two RGB LEDs, driven by nrf91_rgbled.c: the lightwell LED (the large LED in the enclosure light pipe) on PWM0 (P0.29/30/31) as /dev/rgbled0, and the sense LED (next to the sensors) on PWM1 (P0.0/1/2) as /dev/rgbled1. Objects 33002/0/0 (lightwell) and 33003/0/0 (sense) are writable packed 0xRRGGBB colours: write e.g. 0xFF0000 (16711680) from Leshan to set a LED red.

  • Each sensor is cached by a latest program into a virt IO so on-demand reads always return the last sample (uorb reads return -EAGAIN between samples). The BH1749 RGB vector is split by a vecsplit program.

  • GNSS shares the modem with LTE-M (AT%XSYSTEMMODE=1,0,1,0). The nRF91 GNSS driver defers starting the engine until the LTE stack has powered the modem (CFUN), so opening sensor_gnss0 early does not fail.

  • GNSS uses four dedicated sub-IOs (dawn::CIOSensorGnss), all reading sensor_gnss0: gnss (position+velocity), gnss_time (UTC, uint64 seconds), gnss_info (accuracy + DOP) and gnss_sats (uint32 satellite count). The gnss and gnss_info vectors are fanned out by vecsplit into the LwM2M Location object (6) and the custom object 33005; gnss_time / gnss_sats are cached by a latest program so reads return the last value (0 until the first fix) rather than -ENODATA. A position fix requires sky view, so all GNSS resources read 0 until the modem locks.

  • CONFIG_NRF91_MODEM_GNSS_BOOST_PRIO is enabled, but the boost is bounded and satellite-gated: GNSS only preempts LTE idle once it actually sees satellites (CONFIG_NRF91_MODEM_GNSS_BOOST_MINSV, default 4), and the priority is released after a timeout if no fix arrives, with a cool-down before retrying (..._BOOST_TIMEOUT / ..._BOOST_COOLDOWN). Indoors GNSS sees nothing, so LTE is never preempted and the device stays reachable; outdoors GNSS grabs window time, gets the fix, then yields back to LTE.

  • LTE power-save is configurable via CONFIG_DAWN_SYSTEM_LTE_PSAVE (0 = none, 1 = PSM, 2 = eDRX), applied through the LTE API. The default (none) disables PSM/eDRX so the device stays reachable for server-initiated reads.

  • The on-board 24CW160 (16-Kbit / 2 KB) I2C EEPROM (I2C2, 0x50) is registered as /dev/eeprom0 via nrf91_eeprom.c (generic 24xx16 geometry). It is not yet consumed by Dawn – exposed for later use.

Flashing

This non-secure application runs behind the miniboot_s secure bootloader. Build both images and flash over the external J-Link:

source .venv/bin/activate

python -m dawnpy build build_thingy91_wakaama \
  boards/arm/nrf91/thingy91/configs/wakaama \
  -e CXX=g++-14 -e CC=gcc-14

python -m dawnpy build build_thingy91_miniboot_s \
  boards/arm/nrf91/thingy91/configs/miniboot_s \
  -e CXX=g++-14 -e CC=gcc-14

nrfutil device recover
nrfutil device program --firmware build_thingy91_miniboot_s/nuttx.hex \
    --options chip_erase_mode=ERASE_ALL
nrfutil device program --firmware mfw_nrf9160_<ver>.zip
nrfutil device program --firmware build_thingy91_wakaama/nuttx.hex \
    --options chip_erase_mode=ERASE_RANGES_TOUCHED_BY_FIRMWARE
nrfutil device reset

  • nrfutil device recover clears access-port protection and also erases the modem firmware – re-flash mfw_nrf9160_<ver>.zip after a recover.

  • The application is flashed with ERASE_RANGES_TOUCHED_BY_FIRMWARE to keep the bootloader intact.

RTT log

Console and syslog are on RTT channel 0 (there is no UART). View it with JLinkRTTViewer (device nRF9160_xxAA, SWD, channel 0), or:

JLinkExe -device nRF9160_xxAA -if SWD -speed 4000 -autoconnect 1
# in another terminal:
JLinkRTTClient