Dear all

Since few days (and weeks) I try to managed by myself with an I2C issue, but I now freezed.
I made an 5V I2C network with one master and many slaves : some PCF8574 devices and one Teensy 3.2.
I used for Teensy:
- i2c_t3 - I2C library for Teensy 3.x & LC - (v11.0) Modified 01Dec18 by Brian (nox771 at
- a I2C level translator, a PCA9517 with 2.2k pull-up resistors on 3.3V side

All works fine, except that at least once by day, the SCL line stay low. After investigation, I realised that the SCL low is due to the Teensy.
Jumpers on my Teensy's "mother board" allow me to disconnect SDA et SCL of the Teensy to the I2C network.
So, when I disconnect Teensy's SCL of the rest of the network, other I2C re-works, but freeze when I reconnect it.
The only solution was to manualy restart the Teensy (power off and after on).

I have two questions :
1- In a slave mode, what are the reasons for the Teensy act on SCL line?
2- The more importante, because it could happen : How, can I automatically maneged the "I2C module" restart?

Many thanks in advance for your ideas