I2C Bus Stuck When Slave Holds Clock Low (STM32F401) #5
Description
I2C Bus Stuck When Slave Holds Clock Low (STM32F401)
Description:
I’m encountering intermittent I2C bus lock-ups with the SparkFun Optical Tracking Odometry Sensor when using an STM32F401 as the master. The issue manifests either:
On the very first acknowledge byte of a transaction, or
After several successful transactions, communication randomly fails.
In these cases, the slave appears to hold the SCL line low, causing the master to hang.
Setup:
STM32F401 as I2C master.
Pull-ups are configured correctly.
I2C speed: 100 kHz.
Slave: SparkFun Optical Tracking Odometry Sensor.
Steps to Reproduce:
Initialize I2C communication at 100 kHz.
Attempt to read or write data to the sensor.
Sometimes the transaction works; other times, the slave holds SCL low either immediately on the first ACK or after a few successful reads/writes.
Expected Behavior:
The bus should function reliably at 100 kHz without hanging.
Actual Behavior:
Slave occasionally holds SCL low.
Software attempts to reset the bus (disabling/enabling the peripheral, clearing CR1/CR2, sending STOP conditions) do not release the bus.
Attempts to Resolve:
Verified pull-ups are present and strong.
Tried software resets and STOP generation.
Tried multiple retries from the master.
Request:
Guidance on reliably recovering the bus or avoiding this intermittent SCL hold issue would be greatly appreciated. Is this a known issue with certain slaves, or is additional master-side handling required?