Compliance to SMBus Specifications

Hardware-Specific Restrictions

Section 2 of the SMBus 2.0 specifications states that powered-down devices must provide no leakage path to ground. There are ESD diodes placed between VDD and the pads used for SCL and SDA on this device. Assuming VDD is equivalent to ground when powered down, these ESD diodes provide a path to ground.

Implementation in Software

The following elements of the SMBus 2.0 specifications are not implemented in hardware:
  • Table 1 of the SMBus 2.0 specifications gives a maximum clock low timeout (Ttimeout) of 25-35 ms, which can be implemented by connecting the SCL pin to the TCB peripheral using the Event System. Configure the TCB in Time-Out Check mode with the desired timeout value.
  • Layer 3 (network layer) features such as packet error checking (PEC), address resolution protocol (ARP). These can be implemented in software if required.