1. add network channel switch function.
- users can obtain the new channel through the event MESH_EVENT_CHANNEL_SWITCH.
- the entire network will be moved to the same channel as the router without user intervention.
- if no router is in the network, users can call esp_mesh_switch_channel() on the root side to
move the entire network to their desired channel.
2. support not configuring the network channel.
3. support not configuring the router BSSID even if the router is hidden.
4. add allow_channel_switch to mesh configuration.
- if the channel is not specified, this value will be ignored.
- if the channel is specified and this value is set, when "fail" (mesh_attempts_t) times of parent selection
or look for networks are reached, device will change to perform a full channel scan for networks that could join.
- if the channel is specified and this value is set to 0, when a root is not elected, channel switch is not allowed.
but when a root appears, the root performs a full channel scan during the process of connecting to the router,
so even allow_channel_switch is set to 0, the root may still switch channel and eventually the entire network
changes channel.
5. add allow_router_switch to mesh router configuration.
- if the BSSID of router is not specified, this value will be ignored.
- if the BSSID of router is specified and this value is set, when the router of this specified BSSID fails to be found
after "fail" (mesh_attempts_t) times, the entire network is allowed to switch to another router with the same SSID.
6. modify the root to perform a full channel scan when esp_wifi_connect().
7. support handling beacon without DS Paramter Set.
Introduced in 9c23b8e5 and 4f87a62f. To get higher speed, menuconfig
options are added to put ISR and other functions into the IRAM. The
interrupt flag ESP_INTR_FLAG_IRAM is also mistakenly set when the ISR is
put into the IRAM. However callbacks, which are wrote by the user, are
called in the master and slave ISR. The user may not be aware of that
these callbacks are not disabled during flash operations. Any cache miss
during flash operation will cause panic.
Essentially IRAM functions and intrrupt flag ESP_INTR_FLAG_IRAM are
different, the latter means not disabling the ISR during flash
operations. New bus_config flag intr_flags is offered to help set the
interrupt attribute, including priority level, SHARED, IRAM (not
disabled during flash operations). It introduced a small BREAK to
IDFv3.1 (but the same as IDFv3.0) that the user has to manually set IRAM
flag now (therefore he's aware of the IRAM thing) to void the ISR being
disabled during flash operations.
