SPIFlashWrite is called when WiFi config is changed. If you are joining the same network, you don't need to call WiFi.begin, SDK will join the last network without writing anything to flash.
Flash is also written when using SPIFFS, EEPROM, and doing OTA.
By the way, this is related to #836. As a summary, PWM needs the following things fixed:
move timer handler and PWM routines into RAM (need to free up some RAM to do that, possibly by removing espconn from liblwip.a, or moving some strings into flash)
use NMI instead of regular interrupt
refactor existing critical sections in PWM routines
To restart the the Arduino, tap the button next to the Ethernet port two times.
To reset the WiFi press the button located next to the USB-A connector, for longer longer than 5 seconds, but less than 30. The Yún will start its own wiFi network Arduino Yún-XXXXXXXXXXXX. Any other modification/configuration will be retained.
To reset the Linino distribution to its default state, press the WiFi reset button for at least 30 seconds. The board reverts to the original settings as if it had been reflashed or taken out of the box. Among other things, this removes all installed files and network settings.
Bookmarks on this page are managed by an admin user. 