Mediatek Labs LinkIt Connect 7681 Developer's Manual page 38

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WIFI_STATE_ASSOC
MT7681 sends a Management frame (Assoc Request) to AP and waits for a response:
if the Assoc Response is received with the status code =0 (Assoc successful), then:
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if AuthMode is 0 (Open mode), MT7681 goes to WIFI_STATE_CONNED.
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if the AuthMode is 4 (WPAPSK mode), 7 (WPA2PSK mode), or 9 (WPA/WPA2PSK
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mixed mode), MT7681 goes to WIFI_STATE_4WAY.
if Assoc Response is received with status code not equal 0, a Deassoc frame is
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received from the target AP, or an Assoc response frame isn't received within 300ms
after retrying 5 times, MT7681 goes to WIFI_STATE_INIT.
There are sub-states for the Assoc process:
Sub-state = 0, MT7681 is preparing to send an Assoc request.
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Sub-state = 1, MT7681 is waiting for an Assoc response.
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WIFI_STATE_4WAY
MT7681 and the target AP undertake a 4 Way Handshake process and negotiate the PTK
(Pairwise Key) and GTK (Group Key) used for encrypting/decrypting unicast and broadcast
frames when MT7681 and AP communicate:
if the 4 Way Handshake is successful, MT7681 goes to WIFI_STATE_CONNED.
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if 4 Way Handshake fails or the 4 Way Handshake process times out (>10s), MT7681
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goes to WIFI_STATE_INIT.
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WIFI_STATE_CONNED
When MT7681 enters into this state from WIFI_STATE_ASSOC or WIFI_STATE_4WAY it sends
a DHCP discovery request to apply for an IP address from the AP and the AP should assign
an IP address to MT7681.
Once the IP address has been acquired MT7681 should stay in this state until powered
down, however it will go to WIFI_STATE_INIT if:
Beacon is not received from target AP within 20 seconds.
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Deauth or Deassoc is received through a unicast from the AP.
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IP address is not received from DHCP and a retry times out (1 minute).
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AT command AT#Reboot is received.
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Unauthorized reproduction or disclosure of this information in whole or in part is strictly prohibited.
MediaTek LinkIt™ Connect 7681 Developer's Guide
© 2015, 2016 MediaTek Inc. Page 33 of 65