COEX

The COEX interface consists of pins 91–93. It is dedicated for RF interference avoidance towards a companion radio device, such as an external positioning device or Bluetooth® Low Energy device.

The COEX interface is powered from VDD_GPIO. To control the COEX interface, the LTE modem must be active. When the LTE modem is not active, the COEX interface floats. Therefore, it is mandatory to use external pull-down resistors in the size range of 100 kΩ in the COEX interface.

The COEX pins have the following functionalities:

• COEX0 (pin 93)
  • Can be configured for external Global Positioning System (GPS) Low-Noise Amplifier (LNA) control (high state) during GPS receive the same way as the %XMAGPIO command with the exception that %XMAGPIO controls only one pin. For more information, see MAGPIO configuration %XMAGPIO in nRF9160 AT Commands Reference Guide.
• COEX1 (pin 92)
  • Can be used during GPS receive to deliver GPS one pulse per second (1PPS) time mark pulse.
    Note: Supported in a future release of the modem firmware.
• COEX2 (pin 91)
  • Can be used as an indicator of LTE or GPS RF activity from the modem to an external device. When COEX2 is high, the LTE or GPS RF is active, and when it is low, the LTE or GPS RF is inactive.
  • Can be used as a “BLE nGrant”. This means that Bluetooth Low Energy should not transmit when COEX2 is high and Bluetooth Low Energy can transmit when COEX2 is low.
  • Can be used with %XRFTEST AT commands. For more information, see Production test features in nRF9160 AT Commands Reference Guide.