MCT8317A datasheet(69/161 Pages) TI1

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3. The Start Byte is followed by 24-bit Control Word. Bit 23 in the control word has to be 1 as it is a read

operation.

4. The control word is followed by a repeated start or normal start.

5. MCT8317A sends the data bytes on SDA. The number of bytes sent by MCT8317A depends on the DLEN

field value in the control word.

a. While sending data bytes, the LSB byte is sent first. Refer the examples below for more details.

b. 16-bit/32-bit Read – The data from the address mentioned in Control Word is sent back.

c. 64-bit Read – 64-bit is treated as two 32-bit read. The address mentioned in Control Word is taken as

Addr 0. Addr 1 is calculating internally by MCT8317A by incrementing Addr 0 by 2. A total of 8 data

bytes are sent by MCT8317A. The first 4 bytes (sent in LSB first way) are read from Addr 0 and the next

4 bytes are read from Addr 1.

d. MCT8317A takes some time to process the control word and read data from the given address. This

involves some delay. It is quite possible that the repeated start with Target ID will be NACK’d. If the

I2C read request has been NACK’d by MCT8317A, retry after few cycles. During this retry, it is not

necessary to send the entire packet along with the control word. It is sufficient to send only the start

condition with target ID and read bit.

6. If CRC is enabled, then MCT8317A sends an additional CRC byte at the end. If CRC is enabled, external

MCU I2C controller has to read this additional byte before sending the stop bit. CRC is calculated for the

entire packet (Target ID + W bit, Control Word, Target ID + R bit, Data Bytes).

7. I2C stop condition.

TARGET

ID [6:0]

CONTROL

WORD [23:16]

ACK

DATA

BYTES

Read – without CRC

2 / 4 / 8 DATA BYTES

TARGET

ID [6:0]

CRC includes {TARGET ID,0}, CONTROL WORD[23:0], {TARGET ID,1}, DATA BYTES

ACK

CONTROL

WORD [15:8]

ACK

CONTROL

WORD [7:0]

ACK

DATA

BYTES

ACK

TARGET

ID [6:0]

CONTROL

WORD [23:16]

ACK

DATA

BYTES

Read – with CRC

2 / 4 / 8 DATA BYTES

TARGET

ID [6:0]

ACK

CONTROL

WORD [15:8]

ACK

CONTROL

WORD [7:0]

ACK

CRC

DATA

BYTES

ACK

Figure 8-48. I2C Read Operation Sequence

8.6.2.4 Examples of MCT8317A I2C Communication Protocol Packets

All values used in this example section are in hex format. I2C target ID used in the examples is 0x00.

Example for 32-bit Write Operation: Address – 0x00000080, Data – 0x1234ABCD, CRC Byte – 0x45 (Sample

value; does not match with the actual CRC calculation)

Table 8-6. Example for 32-bit Write Operation Packet

Start Byte

Control Word 0

Control Word 1

Control

Word 2

Data Bytes

CRC

Target

I2C

Write

OP_R/

CRC_E

DLEN

MEM_S

MEM_P

AGE

MEM_A

DDR

MEM_A

DDR

DB0

DB1

DB2

DB3

CRC

Byte

A6-A0

CW23

CW22

CW21-

CW20

CW19-

CW16

CW15-

CW12

CW11-

CW8

CW7-

CW0

D7-D0

C7-C0

0x00

0x0

0x1

0x0

0x80

0xCD

0xAB

0x34

0x12

0x45

0x00

0x50

0x00

0x80

0xCD

0xAB

0x34

0x12

0x45

Example for 64-bit Write Operation: Address - 0x00000080, Data Address 0x00000080 - Data 0x01234567,

Data Address 0x00000082 – Data 0x89ABCDEF, CRC Byte – 0x45 (Sample value; does not match with the

actual CRC calculation)

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MCT8317A

SLLSFQ2 – JANUARY 2023

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