I2C clock low level=1.4V

[Emil]

I have an I2C bus with an ESP32 master and two devices (TMP1075 and MM7660).

SCL has a high level of ~3.3V and a low level of ~1.4V. (SDA is normal at ~3.3V high and ~0.1V low.)

I use 4.7K pull-ups on both SCL and SDA. I have also tried removing the resistors and using only the internal pull-ups of the ESP32, with the same result.

Measuring SCL with CH1 gives the same result, so not a problem with the probe or channel settings.

Any suggestions as to what may be causing this?

Code: [Select]

i2c_config_t conf = {0};
conf.mode = I2C_MODE_MASTER;
conf.sda_io_num = 21;
conf.sda_pullup_en = GPIO_PULLUP_DISABLE;
conf.scl_io_num = 22;
conf.scl_pullup_en = GPIO_PULLUP_DISABLE;
conf.master.clk_speed = 100000;
i2c_param_config(i2c_master_port, &conf);
i2c_driver_install(i2c_master_port, conf.mode, 0, 0, 0);

[magic]

Disconnect each device and see what happens?