When the internal LTE radio of nRF9160 wakes up, the initialization phase is applied to the external RFFE device to prepare the RFFE device for transmitting or receiving. The device is set to active low power mode and triggers are disabled. Initialization is needed to avoid long start-up times in later RFFE device control phases.
The syntax of the INIT phase is the following:
%XMIPIRFFECTRL=<dev_id>,0,<n>,<address_0>,<data_0>,…,<address_n-1>,<data_n-1>The following command example initializes an RFFE device with the %XMIPIRFFECTRL AT command:
AT%XMIPIRFFECTRL=1,0,1,28,184The command parameters and their values in the example are the following:
| Parameter name | Parameter description | Value in example | Value description |
|---|---|---|---|
| <dev_id> | The identification number of the MIPI RF Front-End Control Interface (RFFE) device given when it was introduced using %XMIPIRFFEDEV | 1 | |
| <use_case#> | Number of the phase. INIT = 0, ON = 1, OFF = 2, PWR_OFF = 3. All numbers must be given as decimals (hexadecimals not allowed). | 0 | INIT phase |
| <n> | The number of address/data pairs. Valid values are 0, 1, 2, 3, 4. If the value is 0, all the following fields must be omitted. | 1 | Number of register writes in this command |
| <address_x> | The 8-bit address of the internal register in MIPI RFFE device. x = 0, ..., n−1. | 28 | Address of PM_TRIG register (= 0x1C) |
| <data_x> | The 8-bit data to be written to <address_x>. x = 0, ..., n−1. | 184 | Value to write to register address 28. |
The writes in the initialization phase are applied when the modem wakes up. This happens when an initial cell search is started or after a Discontinuous Reception (DRX), Extended Discontinuous Reception (eDRX), or Power Saving Mode (PSM) sleep period.