Tool/software:
Hi,
We are using a SN65DSI83 chip connected to an I2C bus running at 1.8V. This same bus also connects to other devices through a FXMA2102 bus level translator to adapt to 3.3V signals. When the system is used at room temperature or at negative temperatures, all is well. When exposed to +70°C, the SCL bus signal gets degraded by the SN65DSI83 when accessing the other devices on the bus:
Channel 1 : SDA, channel 2 : SCL
The oscilloscope did not decode the I2C bus because of the garbled clock signal. It occurs at every byte once the SDA signal is pulled low (near the center of the frame).
This degradation seems to only occur when the SDA line is pulled low by the addressed I2C device for some time (like just before it starts sending its data). We narrowed it down to the SN65DSI83 chip by heating only this device, leaving the rest of the board at room temperature using a hot air generator locally on the chip. The MIPI DSI bridge is initialized once at power up and its I2C bus is not accessed any more. Reading the time or the EEPROM contents of the devices connected on the same bus show the garbled signal.
Below are the schematics extracts :
MIPI to LVDS bridge
I2C level adapter
Other devices on the bus
