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NBO2_PID_EGO_EXPERIMENT

This is very special, only for people who want to try PID control for NBO2 sensors instead of the bangbang: maybe useful for PNP install on factory cars that have the inferior NBO2

* add NBO2_PID_EGO_EXPERIMENT to my_make

* smartly fill the 5 config parameters below, they are kp, ki, kd, i_limit and deadband, no matter what there names are (reused config variables!)

* make sure MegaTune does not crash mt_unused (forget megatune)

* set config.ego_conf bit0=1 for enabling PID

<code>

// note that NBO2 EGO PID reuses all the 5 values below

uint8_t ego_pid_kp; // ego, incredible speed limit (or pid kp)

uint8_t mt_unused; // Unused, megatune trashes it

uint8_t ego_delta; // ego, step size (percent) [0.4%]

uint8_t ego_target; // ego, target voltage (NBO2)

uint8_t ego_pid_window; // ego, minimum window for pid to react

</code>