STEVAL-ISQ002V1 STMicroelectronics, STEVAL-ISQ002V1 Datasheet - Page 9

• Manufacturer Part Number: STEVAL-ISQ002V1
• Description: BOARD EVAL BASED ON ST72264G1
• Manufacturer: STMicroelectronics

Specifications of STEVAL-ISQ002V1

• Main Purpose: Interface, PMBus
• Embedded: Yes, MCU, 8-Bit
• Utilized Ic / Part: ST72F264
• Primary Attributes: The PMBus™ Interface Using the ST7 I2C Peripheral
• Secondary Attributes: Firmware in C Language
• Product: Power Management Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6423

AN2511
2.1.3
Figure 3.
Inside both PMBus_CommandRead and PMBus_CommandWrite functions,
PMBus_DataLengthCalc is called which calculates the data length based on the
command code received.
Read and write operation
PMBus master performs read/ write operations with the slave device. Depending on the
command code, either PMBus_CommandRead or PMBus_CommandWrite is called. Inside
this function, the SMBus transaction type is selected as shown in the following sequence.
Figure 4.
Check if SMBus_Mode for Word
Check if SMBus_Mode for
Check if SMBus_Mode for
Send Block command
Byte command
command
Flowchart: data length calculation
Flowchart: read operation
START
STOP
No
No
No
Check if command code equal
Check if command code equal
Check if command code equal
to Block protocol
to word protocol
to Byte protocol
Doc ID 13286 Rev 2
S
S
1
S
1
1
START
Yes
Yes
Yes
Slave Address
Slave Address
Slave Address
No
No
No
7
7
7
SMBus Read block protocol
SMBus Read byte protocol
SMBus Read word protocol
Data Byte 1
Wr
Wr
Wr
1
1
1
8
A
A
1
1
A
1
Implementation of PMBus using ST7 I2C
Command Code
Command Code
Command Code
A
1
Yes
Yes
8
8
8
Yes
Data Byte 2
Data Byte High
8
for Word Command
for Block Command
for Byte Command
Byte Count=2,
A
1
1
A
1
A
SMBus_Mode
Byte Count=1,
8
SMBus_Mode
Byte Count=6,
SMBus_Mode
Sr
1
S
S
1
Update
1
Update
Update
1
A
Slave Address
Slave Address
Slave Address
1
A
...
...
7
7
7
1
P
Data Byte N
8
Rd
Rd
Rd
1
1
1
1
A
A
1
A
1
A
STOP
1
Count Byte = 1
Data Byte Low
Data Byte
1
P
8
8
8
1
A
1
A
1
A
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P
...
...
1