Nordic nRF91
The nRF91 series of chips from Nordic Semiconductor are based around an ARM Cortex-M33 core with integrated LTE-M/NB-IoT modem and GNSS.
Modem Support
Modem is supported in the nRF91 using Nordic’s Modem library.
Supported modem features:
Modem feature |
Support |
Notes |
|---|---|---|
AT |
Yes |
|
Socket |
Yes |
via |
SIOCLTECMD |
Partial |
|
GNSS |
Yes |
|
AGPS |
No |
|
Bootloader |
No |
|
Delta DFU |
No |
|
Modem Trace |
No |
At this point there is no application that would configure and enable the modem
automatically at the boot, so it has to be done manually via AT commands on /dev/modem.
IMPORTANT: modem firmware works only in TZ non-secure environment.
Peripheral Support
The following list indicates peripherals supported in NuttX:
Peripheral |
Support |
Notes |
|---|---|---|
CRUPTOCELL |
No |
|
DPPI |
No |
|
EGU |
No |
|
GPIO |
Yes |
|
GPIOTE |
Yes |
|
IPC |
Yes |
nrfx compatible |
I2S |
No |
|
KMU |
No |
|
PDM |
No |
|
PWM |
Yes |
|
RTC |
Yes |
|
SPIM |
Yes |
|
SPIS |
No |
|
SPU |
Yes |
|
TIMER |
Yes |
|
TWIM |
Yes |
|
TWIS |
No |
|
UART |
Yes |
|
UARTE |
No |
|
WDT |
No |
I2C
I2C is supported both in polling and interrupt mode (via EasyDMA).
Note
The I2C peripheral does not support sending two transfers without sending a START nor RSTART. For this reason, this is supported via an internal buffer where messages will be first copied to and sent together.
The lower-half of I2C bus is initialized by nrf91_i2cbus_initialize().
SPI
SPI is supported both in polling and interrupt-based (via EasyDMA) mode. The latter supports arbitrarily long transfers using Nordic’s list-mode EasyDMA (intermediate transfers are currently still manually started).
It is possible to use SPI without either MOSI/MISO pin defined by simply not providing
the relevant BOARD_SPI*_MISO/MOSI_PIN definition.
This implementation support power management hooks, which will disable SPI peripheral when entering either SLEEP or STANDBY modes and reconfigure it when going back to NORMAL mode.
UART
UART is implemented using polling. UARTE EasyDMA feature is not yet supported. This may introduce a large number of interrupts which may be undesirable.
PWM
PWM is supported via standard driver. This means that more advanced features such as complex sequences or waveform modes are not yet supported.
TIMER
The TIMER peripheral is exposed as standard timer.
RTC
The RTC peripheral is exposed as a standard timer, since it is really a low-power timer, without any date handling capabilities.
Tool Issues
OpenOCD
There is no official support for Nordic Cortex M33 chips (nRF9160 or nRF5340).
Segger J-Link
To start the GDB servers for the application core, use these commands:
JLinkGDBServer -device nRF9160 -if SWD -speed 4000 -port 2331
Then you can connect GDB to targets:
(gdb) target remote localhost:2331