MCF8315A read transaction over I²C involves the following sequence (see Figure 7-58).

1. I²C Start condition from the controller to initiate the transaction.
2. Start is followed by the I²C target ID byte, made up of 7-bit target ID along with the R/W bit set to 0b. ACK (in yellow box) indicates that MCF8315A has processed the received target ID which has matched with it's I²C target ID and therefore will proceed with this transaction. If target ID received does not match with the I²C ID of MCF8315A, then the transaction is ignored and no ACK is sent by MCF8315A.
3. The target ID byte is followed by the 24-bit control word sent one byte at a time. Bit 23 in the control word is set to 1b as it is a read transaction. ACK (in blue boxes) correspond to acknowledgements sent by MCF8315A to the controller that the previous byte (of control word) has been received and next byte can be sent.
4. The control word is followed by a Repeated Start (RS, start without a preceding stop) or normal Start (P followed by S) to initiate the data (to be read back) transfer from MCF8315A to I²C controller. RS or S is followed by the 7-bit target ID along with R/W bit set to 1b to initiate the read transaction. MCF8315A sends an ACK (in grey box after RS) to the controller to acknowledge the receipt of read transaction request.
5. Post acknowledgement of read transaction request, MCF8315A sends the data bytes on SDA one byte at a time. The number of data bytes sent by MCF8315A depends on the DLEN field in the control word.
   1. While sending data bytes, the LSB byte is sent first. Refer the examples in Section 7.6.2.4 for more details.
   2. 16-bit/32-bit Read – The data from the address mentioned in control word is sent back to the controller.
   3. 64-bit Read – 64-bit is treated as two successive 32-bit reads. The address mentioned in control word is taken as Addr_1. Addr_2 is internally calculated by MCF8315A by incrementing Addr_1 by 0x2. A total of 8 data bytes are sent by MCF8315A. The first 4 bytes (sent in LSB first) are read from Addr_1 and the next 4 bytes are read from Addr_2.
   4. ACK in orange boxes correspond to acknowledgements sent by the controller to MCF8315A that the previous byte has been received and next byte can be sent.
6. If CRC is enabled in the control word, then MCF8315A sends an additional CRC byte at the end. Controller has to read the CRC byte and then send the last ACK (in orange). CRC is calculated for the entire packet (Target ID + W bit, Control Word, Target ID + R bit, Data Bytes).
7. I²C Stop condition from the controller to terminate the transaction.

Figure 7-58 I²C Read Transaction Sequence