Set/Get Maximum Read Length (SETMRL/GETMRL)

The Controller uses the Direct and Broadcast SETMRL CCC to set the maximum data read length and maximum IBI payload size for the Target, which are stored in the I3CxMRL and I3CxIBIPSZ registers respectively.

The Controller uses the Direct GETMRL CCC to read the maximum data read length and maximum IBI payload size from the Target. This CCC transmits the I3CxMRL and I3CxIBIPSZ registers from the Target with the Most Significant bit first.

The frame format for Direct SETMRL/GETMRL CCC is shown in Figure 1, whereas the frame format for the Broadcast SETMRL is shown in Figure 2.

Important:
  1. 1.The minimum I3CxMRL Maximum Read Length value the Controller can set is 16.
  2. 2.The I3CxIBIPSZ register value is the size of the IBI payload (excluding Mandatory Data Byte) in bytes. The minimum IBI payload size is ‘1’ (just the Mandatory Data Byte when I3CxIBIPSZ = 0) and the maximum IBI payload size is 256 (including the Mandatory Data Byte when I3CxIBIPSZ = 0xFF = 255). Refer to IBI Payload and Mandatory Data Byte for details.
Figure 1. Direct SETMRL/GETMRL Frame Format
Figure 2. Broadcast SETMRL Frame Format