I'm using a T3.5 to manage an array of seven ST Micro VL53L0X ToF distance sensors, 3 on Wire1 and 4 on Wire2. All seven are powered from the 3.3V output pin. The T3.5 and the sensors are mounted on an autonomous wall-following robot. The robot knows how to connect to a charging station when its battery gets low, and the connection process involves driving itself onto a charging probe with enough velocity to ensure it connects, and this event is somewhat 'energetic'.
I am using pin headers on the T3.5, so occasionally when the robot connects to its charging station, the jumper wire connected to the +3.3V output exhibits contact bounce sufficient to take the sensors offline very briefly. Unfortunately, the I2C architecture used by the VL53L0X device is very intolerant of any power disruption, and one or more of the sensors will restart in their default configuration, and they all wind up at the same I2C address.
One solution I am considering is to install a BAC (Big-Assed Capacitor) on the 3.3V output to flywheel through any 'contact bounce' events on the 3.3V line when the robot hits the physical stop as it connects to the charging station. I have looked at the datasheet for the LP38691 LDO regulator specified for the T3.5, and it appears it has a 'foldback' mechanism to prevent damage to the regulator due to high charging current when the main power is first applied. Does anyone have any additional information that would indicate this will be a problem?
Here's the schematic for the sensor array sub-system:
TIA,
Frank
I am using pin headers on the T3.5, so occasionally when the robot connects to its charging station, the jumper wire connected to the +3.3V output exhibits contact bounce sufficient to take the sensors offline very briefly. Unfortunately, the I2C architecture used by the VL53L0X device is very intolerant of any power disruption, and one or more of the sensors will restart in their default configuration, and they all wind up at the same I2C address.
One solution I am considering is to install a BAC (Big-Assed Capacitor) on the 3.3V output to flywheel through any 'contact bounce' events on the 3.3V line when the robot hits the physical stop as it connects to the charging station. I have looked at the datasheet for the LP38691 LDO regulator specified for the T3.5, and it appears it has a 'foldback' mechanism to prevent damage to the regulator due to high charging current when the main power is first applied. Does anyone have any additional information that would indicate this will be a problem?
Here's the schematic for the sensor array sub-system:
TIA,
Frank