PTA 3-Wire Co-Ex Mechanism#

PTA is an external co-existence mechanisms designed to reduce packet collisions between coupled devices using different protocols like Thread®/Zigbee, Wi-Fi, and BT/BLE. In this implementation, SiWG917 acts as the PTA Main controlling the access to the spectrum to itself or the EFR32 based on three handshake signals.

The following three signals are implemented in the proposed 3-Wire PTA solution to establish the handshake between SiWG917 and EFR32MG21, as illustrated in the below figure.

REQUEST

  • Input to SiWG917; Output from EFR32.

  • EFR32 requests GRANT channel access to the 2.4GHz band for transmission and reception (Tx/Rx).

PRIORITY

  • Input to SiWG917; Output from EFR32.

  • EFR32 asserts this signal to indicate high-priority traffic, thereby requesting Grant access to the 2.4 GHz band for Tx/Rx.

GRANT

  • Output from SiW91x; input to EFR32.

  • SiWG917 asserts this signal to grant access to the 2.4 GHz ISM Band for Tx/Rx.

PTA 3-Wire MechanismPTA 3-Wire Mechanism

When the Zigbee device requires access to the spectrum, it asserts the REQUEST signal. Depending on the PTA configuration, the SiWG917 responds by asserting the GRANT signal. In some configurations, GRANT is asserted only when both REQUEST and PRIORITY signals are active.