Questions regarding Generic three-wire coexistence pulses on nRF54L15

RE: Questions regarding Generic three-wire coexistence pulses on nRF54L15

Amanda Hsieh — Fri, 16 Jan 2026 21:47:52 GMT

Hi,

[quote user="David Duan"]Should the PTA switch to BT when the req-gpios signal is high, and switch to Wi-Fi when the req-gpios is low?[/quote]

It depends on its internal arbitration and configuration, not just the REQ level. In the Shared Antenna mode, the PTA makes priority decisions, controls the switch between Bluetooth LE/IEEE 802.15.4 and Wi-Fi. The PTA also grants TX/RX requests from the Bluetooth LE/IEEE 802.15.4 device. Only one interface, either Bluetooth LE/IEEE 802.15.4 or or Wi-Fi is connected to the antenna at any time. See Coexistence.

[quote user="David Duan"]Does the grant-gpio signal level follow the req-gpios? Specifically, does grant-gpio go high when req-gpios is high, and go low when req-gpios is low?[/quote]

GRANT is driven by the PTA according to its timing and arbitration rules (e.g., it may stay low/negated even while REQ is high if Wi‑Fi keeps the medium, or be asserted only during an allowed window). See Bluetooth LE/IEEE 802.15.4 timing

-Amanda H.

RE: Questions regarding Generic three-wire coexistence pulses on nRF54L15

David Duan — Fri, 16 Jan 2026 01:09:07 GMT

Hi Amanda,

Thank you for your reply. My client has two additional questions that require your confirmation:

Should the PTA switch to BT when the req-gpios signal is high, and switch to Wi-Fi when the req-gpios is low?
Does the grant-gpio signal level follow the req-gpios? Specifically, does grant-gpio go high when req-gpios is high, and go low when req-gpios is low?

RE: Questions regarding Generic three-wire coexistence pulses on nRF54L15

Amanda Hsieh — Wed, 14 Jan 2026 14:48:49 GMT

Hi David,

[quote user=""]Is the pulse on req-gpios exactly the duration for which the Bluetooth radio needs to be used? For example, if the pulse on req-gpios is 519us during a Bluetooth connection, can it be understood that the nRF54L15 requires the RF for 519us?[/quote]

Yes, there are some added delays, etc., to ensure that any external circuitry is being switched/told about this change, but generally, yes.

[quote user=""]If my understanding of the first question is correct, can the Wi-Fi host perform RF switching according to the following logic: When the Wi-Fi host detects a transition from low to high on req-gpios, it sets grant-gpios to high to switch the RADIO to the nRF54L15. When req-gpios transitions from high to low, the Wi-Fi host sets grant-gpios to low to switch the RF back to Wi-Fi.[/quote][quote user=""]Currently, we are attempting to use the Generic three-wire coexistence (refer link: https://docs.nordicsemi.com/bundle/ncs-2.9.2/page/nrf/app_dev/device_guides/wifi_coex.html )feature on the nRF54L15 to implement PTA (Packet Traffic Arbitration) control with a Wi-Fi host (BES2610).[/quote]

That wifi host is a non-Nordic device. I would recommend that you ask the manufacturer.

Regards,
AmandaH.