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Hi, in the 802.11 reference design lower MAC code, it looks like the lower MAC core is polling PHY Rx pipeline to detect the start of a PHY reception, using this function `wlan_mac_low_poll_frame_rx()`.
At which particular point in PHY reception (energy detection high, auto-correlation detection, or preamble LTS detection) does this function returns the PHY status? What are the available MAC-PHY statuses that can be polled?
Thank you for your help.
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At which particular point in PHY reception (energy detection high, auto-correlation detection, or preamble LTS detection) does this function returns the PHY status? What are the available MAC-PHY statuses that can be polled?
We use the 802.11 definition of RX_START, when the PHY has decoded a SIGNAL field and is proceeding with a packet reception attempt. This can only occur after a successful packet detection, LTS correlation and decoding of the first OFDM symbol, which contains the 3-byte SIGNAL field.
You can poll the Rx PHY's packet detection status with wlan_phy_rx_get_pkt_det_status(). This will return a 5-bit value, where each bit indicates a packet detection state. Bits 0:3 are RFA/B/C/D. Bit 4 is the external packet detection circuit. Typically only the RF A bit will assert. It asserts when either packet detection subsystem (auto-corr or RSSI) asserts and stays asserted until the Rx PHY is done. The PHY will finish when:
-LTS correlation fails, otherwise
-SIGNAL decoding fails, otherwise
-Payload decoding completes
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