AN2511
Application note
PMBusTM interface using ST7 I2C
Introduction
The PMBusTM (power management bus) is an open standard protocol that defines a means
of communicating with power conversion and other devices. The PMBus protocol helps to
establish the first truly open communications standard for the digital control of power
systems. Implemented over the industry-standard SMBus (system management bus) serial
interface, the PMBus protocol facilitates the programming, control and real-time monitoring
of compliant power conversion products.
This application note describes how to use the ST7 I2C peripheral for PMBus
communication. The firmware of this application performs the PMBus bus protocols
mentioned in PMBusTM power system management protocol specification v1.0. The device
chosen here is ST72264G1 which has multi-master I2C capability. This microcontroller acts
as the PMBus master. It controls the PMBus compatible slaves. The firmware described in
this application note is in C language.
To show the PMBus capabilities of ST7, a dedicated demonstration board is developed. This
board consists of the ST72F264G1 microcontroller and it works with PC hyperterminal. The
objective of this demonstration board is to show to the user the features and capabilities of
PMBus features using ST7 I2C peripheral, to support the standard PMBus commands. The
results of this demonstration board interfaced with Artesyn's PMBus module are shown in
this application note.
August 2010
Doc ID 13286 Rev 2
1/43
www.st.com
Contents
AN2511
Contents
1
PMBus introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1
1.2
2
4
5
6
SMBus version 1.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1.2
Extensions to SMBus version 1.1 specification . . . . . . . . . . . . . . . . . . . . 6
Hardwired signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.1
Electrical interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2.2
Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Firmware architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.1
I2C initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.2
Slave address and command code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.3
Read and write operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
PMBus commands and source code . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.1
PMBus commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2
Source code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.3
Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.4
Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
PMBus interfacing results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1
Interfacing with Artesyn module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.2
Interfacing with SiLabs module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
PMBus demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.1
System requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.2
Software setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.3
Hardware setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Using the demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.1
2/43
1.1.1
Implementation of PMBus using ST7 I2C . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1
3
PMBus protocol description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Normal operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.1.1
Selection of communication speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.1.2
Selection of packet error checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
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Contents
6.2
7
6.1.3
Selection of slave address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.1.4
Selection of read/write mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1.5
Single read mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1.6
Continuous read mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1.7
Write mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.1.8
Group command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Error conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.2.1
Invalid command code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
6.2.2
Communication timeout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Hardware description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.1
Schematic and layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
7.2
Bill of materials (BOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
7.3
Demonstration board photo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Appendix A Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
A.1
RS232 configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
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List of tables
AN2511
List of tables
Table 1.
Table 2.
Table 3.
Table 4.
Table 5.
Table 6.
Table 7.
Table 8.
Table 9.
Table 10.
Table 11.
Table 12.
Table 13.
Table 14.
Table 15.
Table 16.
Table 17.
Table 18.
Table 19.
Table 20.
Table 21.
Table 22.
Table 23.
Table 24.
Table 25.
Table 26.
Table 27.
Table 28.
Table 29.
Table 30.
Table 31.
Table 32.
Table 33.
Table 34.
Table 35.
Table 36.
Table 37.
Table 38.
Table 39.
Table 40.
Table 41.
Table 42.
Table 43.
Table 44.
4/43
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
ON_OFF_CONFIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
CLEAR_FAULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
RESTORE_DEFAULT_ALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
STORE_USER_ALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
VOUT_MODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
VOUT_COMMAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VOUT_MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VOUT_MARGIN_HIGH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VOUT_MARGIN_LOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VOUT_OV_WARN_LIMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
VOUT_UV_WARN_LIMIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
IOUT_OC_FAULT_LIMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
IOUT_OC_WARN_LIMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
OT_FAULT_LIMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
OT_FAULT_RESPONSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
OT_WARN_LIMIT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
TON_DELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
TON_RISE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
TOFF_DELAY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
TOFF_FALL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
STATUS_BYTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
STATUS_WORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
STATUS_VOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
STATUS_IOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
STATUS_TEMPERATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
STATUS_MFR_SPECIFIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
READ_VOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
READ_IOUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
READ_TEMPERATURE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
PMBUS_REVISION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
MFR_ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
MFR_MODEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
MFR_REVISION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
MFR_LOCATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MFR_DATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MFR_SERIAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MFR_SPECIFIC_00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
MFR_SPECIFIC_01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
MFR_SPECIFIC_02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
PMBus interfacing with Artesyn module: results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
PMBus interfacing with SiLabs module: results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Document revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
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AN2511
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
Figure 9.
Figure 10.
Figure 11.
Figure 12.
Figure 13.
Figure 14.
Figure 15.
Figure 16.
Figure 17.
Figure 18.
Figure 19.
Figure 20.
Figure 21.
Figure 22.
Figure 23.
Figure 24.
Figure 25.
Figure 26.
Figure 27.
Figure 28.
Figure 29.
Figure 30.
Interface diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Flowchart: I2C initialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Flowchart: data length calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Flowchart: read operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Flowchart: write operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
PC hyperterminal application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Baud rate configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Hyperterminal settings - ASCII setup configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Hyperterminal message to show company name and selection of communication speed 30
PEC selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Slave address entry message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Wrong slave address entry - response 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Wrong slave address entry - response 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Options to select read/ write mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Single read operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Continuous read operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Write mode command code entry message from hyperterminal . . . . . . . . . . . . . . . . . . . . 32
Write mode data entry message from hyperterminal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Write mode operation example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Read operation to check data writing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Group command code entry message from hyperterminal. . . . . . . . . . . . . . . . . . . . . . . . . 34
Group command operation example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Invalid command message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Example of invalid command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Communication timeout message . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Demonstration board schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Top view layout of the demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Bottom view layout of the demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
STEVAL-ISQ002V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Pin description of RS232 D9 connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
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PMBus introduction
AN2511
1
PMBus introduction
1.1
PMBus protocol description
The PMBus protocol is intended to cover a wide range of power system architectures and
converters.
PMBus devices must use the system management bus (SMBus), version 1.1. Implemented
over the industry-standard SMBus serial interface, the PMBus protocol facilitates the
programming, control and real-time monitoring of compliant power conversion products.
1.1.1
SMBus version 1.1
The system management bus (SMBus) is a two-wire interface through which various system
component chips can communicate with each other and with the rest of the system. It is
based on the principles of operation of I2C.
For more information about SMBus, refer to AN1713, available from www.st.com.
1.1.2
Extensions to SMBus version 1.1 specification
1.
Block write-block-read process call
To support certain commands of the PMBus command language, PMBus devices must
support the "Block write-block-read process call" described in Section 5.5.8 of Version
2.0 of the SMBus Specification.
2.
Host notify protocol
PMBus devices may support the host notify protocol described in Section 5.5.9 of
Version 2.0 of the SMBus Specification. If a PMBus device supports the host notify
protocol, the two data bytes sent to the host are the same as the data bytes returned by
the STATUS_WORD command.
3.
Group command protocol
PMBus devices must support the group command protocol. The group command
protocol is used to send commands to more than one PMBus device. The commands
are received in one transmission. When the devices detect the STOP condition that
ends the command, they all begin executing the command they received.
4.
Addressing
PMBus devices use seven bit addresses.
5.
Packet error checking (PEC)
Support for the SMBus packet error checking (PEC) protocol is optional.
1.2
Hardwired signals
1.2.1
Electrical interface
The following diagram shows the interface between different PMBus devices. ST72264G1 is
the selected microcontroller, which has a multi-master I2C interface. This microcontroller
acts as PMBus master. It communicates with any compatible PMBus slave using a 4-pin
interface. SMBC is the clock from the master. SMBD is the data pin. Both SMBC and SMBD
should be pulled up with a 4.7 kΩ resistor. SMBALERT is the SMBus alert pin, which helps
6/43
Doc ID 13286 Rev 2
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PMBus introduction
the slave to alert the master whenever it wants to communicate. The control pin is used to
switch ON or OFF a PMBus slave.
Figure 1.
Interface diagram
PMBus Master
PMBus Slave
(ST72F264G1)
SMBC (SCL)
SMBD (SDA)
SMBC
SMBD
SMBA (PA3)
CONTROL (PC0)
SMBA
CONTROL
The CONTROL signal is an input signal on a power converter. It is used to turn the unit on
and off in conjunction with commands received via the serial bus. It can be configured as an
active high or active low signal through the ON_OFF_CONFIG command (refer to
Section 3.1).
This signal is optional but recommended.
1.2.2
Timing
No specific requirements are made when a PMBus device must respond to a state change
of a hardwired signal.
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Implementation of PMBus using ST7 I2C
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2
Implementation of PMBus using ST7 I2C
2.1
Firmware architecture
This section explains sequence of operation for different software modules.
2.1.1
I2C initialization
To use ST7 I2C for PMBus communication, the peripheral is initialized for 100 kHz
communication speed. The I2C is configured with an address of 0x30, as it can act as a
slave due to its multi-master capability. The following flowchart shows the sequence.
Figure 2.
Flowchart: I2C initialization
START
Initialize I2C CR, CCR,
OAR1 and OAR2 registers
Configure slave addresses
in OAR1 and OAR2
Enable I2C peripheral and
acknowledge in I2CCR register
Set communication speed as
100kHz in I2CCCR register
STOP
The above flowchart is implemented in the function PMBus_Init.
2.1.2
Slave address and command code
The PMBus master addresses the slave with a 7-bit address. Once the slave device
acknowledges the address, the command code is sent corresponding to the PMBus
command and SMBus protocol (refer to Section 3.1).
Then, the microcontroller decodes the command code as shown in the following sequence.
Simultaneously, the SMBus_Mode variable is updated.
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Implementation of PMBus using ST7 I2C
Figure 3.
Flowchart: data length calculation
START
Byte Count=6,
Update
SMBus_Mode
for Block Command
Yes
Check if command code equal
to Block protocol
No
Byte Count=1,
Update
SMBus_Mode
for Byte Command
Yes
Check if command code equal
to Byte protocol
No
Yes
Check if command code equal
to word protocol
Byte Count=2,
Update
SMBus_Mode
for Word Command
No
STOP
Inside both PMBus_CommandRead and PMBus_CommandWrite functions,
PMBus_DataLengthCalc is called which calculates the data length based on the
command code received.
2.1.3
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.
Flowchart: read operation
START
Yes
Check if SMBus_Mode for
Byte command
SMBus Read byte protocol
1
7
1
1
8
1
1
7
1
1
8
1
1
S
Slave Address
Wr
A
Command Code
A
S
Slave Address
Rd
A
Data Byte
A
P
No
Check if SMBus_Mode for Word
command
Yes
SMBus Read word protocol
1
7
1
1
8
1
1
7
1
1
8
1
S
Slave Address
Wr
A
Command Code
A
S
Slave Address
Rd
A
Data Byte Low
A
...
No
Yes
Check if SMBus_Mode for
Send Block command
No
8
1
1
Data Byte High
A
P
SMBus Read block protocol
1
7
1
1
8
1
1
7
1
1
8
1
S
Slave Address
Wr
A
Command Code
A
Sr
Slave Address
Rd
A
Count Byte = 1
A
...
STOP
8
1
8
1
...
8
1
1
Data Byte 1
A
Data Byte 2
A
...
Data Byte N
A
P
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Implementation of PMBus using ST7 I2C
Figure 5.
AN2511
Flowchart: write operation
START
Yes
Check if SMBus_Mode for
Send Byte command
SMBus Send byte protocol
1
7
1
1
8
1
1
S
Slave Address
Wr
A
Data Byte
A
P
No
Yes
Check if SMBus_Mode for Write
Byte command
Check if SMBus_Mode for Write
Word command
SMBus Write byte protocol
1
7
1
1
8
1
8
1
1
S
Slave Address
Wr
A
Command Code
A
Data Byte
A
P
Yes
SMBus Write word protocol
1
7
1
1
8
1
8
1
8
1
1
S
Slave Address
Wr
A
Command Code
A
Data Byte Low
A
Data Byte HIgh
A
P
No
Yes
Check if SMBus_Mode for
Write Block command
No
SMBus Write block protocol
1
7
1
1
8
1
8
1
1
8
1
S
Slave Address
Wr
A
Command Code
A
Byte Count = N
Rd
A
Data Byte 1
A
...
STOP
8
1
...
8
1
1
Data Byte 2
A
...
Data Byte N
A
P
During the PMBus communication, if there are any errors in communication (acknowledge
failure, arbitration loss, bus error or SMBus timeout), the I2C peripheral is disabled. It is reinitialized again inside the PMBus write/ read functions.
In case the SMBus Alert pin is pulled low by the slave to inform the master that it wants to
communicate, the slave address is programmed with the alert response address (0x18).
This is acknowledged by the slave that alerted the master. After the communication between
the master and slave is complete, the slave address is programmed with the user-defined
slave address. The default value of this user-defined address is 0x30.
In case of group operation, the write operation flowchart is followed without the stop
condition.
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PMBus commands and source code
3
PMBus commands and source code
3.1
PMBus commands
The Part II - command language document of PMBus™ Power System Management
Protocol Specification v1.0 provides the list of PMBus commands. This driver supports the
following list of commands. For each command a table is given.
Table 1.
Operation
Command name
OPERATION
Command code
01h
Description
The OPERATION command is used to turn the
unit on and off in conjunction with the input from
the CONTROL (OUTEN) pin.
SMBus transaction type
Read/ Write byte
Number of data bytes
1
Table 2.
ON_OFF_CONFIG
Command name
ON_OFF_CONFIG
Command code
02h
Description
The ON_OFF_CONFIG command configures the
combination of CONTROL (OUTEN) pin input
and serial bus commands needed to turn the unit
on and off.
SMBus transaction type
Read/ Write byte
Number of data bytes
1
Table 3.
CLEAR_FAULTS
Command name
CLEAR_FAULTS
Command code
03h
Description
CLEAR_FAULTS is used to clear any fault bits
that have been set.
SMBus transaction type
Send byte
Number of data bytes
0
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PMBus commands and source code
Table 4.
RESTORE_DEFAULT_ALL
Command name
RESTORE_DEFAULT_ALL
Command code
12h
Description
The RESTORE_DEFAULT_ALL command
instructs the PMBus device to copy the entire
contents of the non-volatile default store memory
to the matching locations in the operating
memory. Any items in default store that do not
have matching locations in the operating memory
are ignored.
SMBus transaction type
Send byte
Number of data bytes
0
Table 5.
STORE_USER_ALL
Command name
STORE_USER_ALL
Command code
15h
Description
The STORE_USER_ALL command instructs the
PMBus device to copy the entire contents of the
operating memory to the matching locations in
the non-volatile user store memory. Any items in
operating memory that do not have matching
locations in the user store are ignored.
SMBus transaction type
Send byte
Number of data bytes
0
Table 6.
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VOUT_MODE
Command name
VOUT_MODE
Command code
20h
Description
VOUT_MODE command, used for commanding
and reading output voltage, consists of a three bit
mode (only linear format is supported.) and a
five-bit parameter representing the exponent
used in output voltage Read/Writes.
SMBus transaction type
Read/ Write byte
Number of data bytes
1
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PMBus commands and source code
Table 7.
VOUT_COMMAND
Command name
VOUT_COMMAND
Command code
21h
Description
VOUT_COMMAND is used to set the output
voltage, in volts (linear format).
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 8.
VOUT_MAX
Command name
VOUT_MAX
Command code
24h
Description
The VOUT_ MAX command sets an upper limit
on the output voltage the unit can command
regardless of any other commands or
combinations.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 9.
VOUT_MARGIN_HIGH
Command name
VOUT_MARGIN_HIGH
Command code
25h
Description
This VOUT_MARGIN_HIGH command loads the
unit with the voltage to which the output is to be
changed when the OPERATION command is set
to "Margin High".
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 10.
VOUT_MARGIN_LOW
Command name
VOUT_MARGIN_LOW
Command code
26h
Description
This VOUT_MARGIN_LOW command loads the
unit with the voltage to which the output is to be
changed when the OPERATION command is set
to "Margin Low".
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 11.
VOUT_OV_WARN_LIMIT
Command name
VOUT_OV_WARN_LIMIT
Command code
42h
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PMBus commands and source code
Table 11.
VOUT_OV_WARN_LIMIT (continued)
Description
The VOUT_OV_WARN_LIMIT command sets the
value of the output voltage at the sense or output
pins that causes an output voltage high warning.
This value is typically less than the output
overvoltage threshold.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 12.
VOUT_UV_WARN_LIMIT
Command name
VOUT_UV_WARN_LIMIT
Command code
43h
Description
The VOUT_UV_WARN_LIMIT command sets the
value of the output voltage at the sense or output
pins that causes an output voltage low warning.
This value is typically greater than the output
undervoltage fault threshold
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 13.
IOUT_OC_FAULT_LIMIT
Command name
IOUT_OC_FAULT_LIMIT
Command code
46h
Description
The IOUT_OC_FAULT_LIMIT command sets the
value of the sense output current, in amps (literal
format), that causes an overcurrent fault.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 14.
IOUT_OC_WARN_LIMIT
Command name
IOUT_OC_WARN_LIMIT
Command code
4Ah
Description
The IOUT_OV_WARN_LIMIT command sets the
value of the output current that causes an output
overcurrent warning.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 15.
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OT_FAULT_LIMIT
Command name
OT_FAULT_LIMIT
Command code
4Fh
Description
The OT_FAULT_LIMIT command sets the value
of the sense temperature, in °C (literal format),
that causes an overtemperature fault
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PMBus commands and source code
Table 15.
OT_FAULT_LIMIT (continued)
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 16.
OT_FAULT_RESPONSE
Command name
OT_FAULT_RESPONSE
Command code
50h
Description
The OT_FAULT_RESPONSE command instructs
the device on what action to take in response to
an overtemperature fault.
SMBus transaction type
Read/ Write byte
Number of data bytes
1
Table 17.
OT_WARN_LIMIT
Command name
OT_WARN_LIMIT
Command code
51h
Description
The OT_WARN_LIMIT command sets the value
of the sense temperature, in °C (literal format),
that causes an overtemperature warning.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 18.
TON_DELAY
Command name
TON_DELAY
Command code
60h
Description
The TON_DELAY sets the time, in ms, from when
a start condition is received (CONTROL signal
asserted and a valid OPERATION command
received) until the output voltage starts to rise.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 19.
TON_RISE
Command name
TON_RISE
Command code
61h
Description
The TON_RISE sets the time, in ms, from when
the output starts to rise until the voltage has
entered the regulation band.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 20.
TOFF_DELAY
Command name
TOFF_DELAY
Command code
64h
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PMBus commands and source code
Table 20.
TOFF_DELAY (continued)
Description
The TOFF_DELAY sets the time, in ms, from
when a stop condition is received (CONTROL
signal negated or a valid OPERATION command
received) until the unit stops transferring energy
to the output.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 21.
TOFF_FALL
Command name
TOFF_FALL
Command code
65h
Description
The TOFF_FALL sets the time, in ms, from the
end of the turnoff delay time until the voltage is
commanded to zero. Note that this command can
only be used with a device whose output can sink
enough current to cause the output voltage to
decrease at a controlled rate.
SMBus transaction type
Read/ Write word
Number of data bytes
2
Table 22.
STATUS_BYTE
Command name
STATUS_BYTE
Command code
78h
Description
The STATUS_BYTE command returns one byte
of information with a summary of the most critical
faults
SMBus transaction type
Read byte
Number of data bytes
1
Table 23.
STATUS_WORD
Command name
STATUS_WORD
Command code
79h
Description
The STATUS_WORD command returns two
bytes of information with a summary of the units
fault condition.
SMBus transaction type
Read word
Number of data bytes
2
:
Table 24.
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AN2511
STATUS_VOUT
Command name
STATUS_VOUT
Command code
7Ah
Description
The STATUS_VOUT commands returns one byte
with status information on Vout.
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PMBus commands and source code
Table 24.
STATUS_VOUT (continued)
SMBus transaction type
Read byte
Number of data bytes
1
Table 25.
STATUS_IOUT
Command name
STATUS_IOUT
Command code
7Bh
Description
STATUS_IOUT commands returns one byte with
status information on Iout.
SMBus transaction type
Read byte
Number of data bytes
1
Table 26.
STATUS_TEMPERATURE
Command name
STATUS_TEMPERATURE
Command code
7Dh
Description
STATUS_TEMPERATURE commands returns
one byte with status information on temperature.
SMBus transaction type
Read byte
Number of data bytes
1
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PMBus commands and source code
Table 27.
STATUS_MFR_SPECIFIC
Command name
STATUS_MFR_SPECIFIC
Command code
80h
Description
STATUS_MFR_SPECIFIC commands returns
one byte with the manufacturer specific status
information.
SMBus transaction type
Read byte
Number of data bytes
1
Table 28.
READ_VOUT
Command name
READ_VOUT
Command code
8Bh
Description
The READ_VOUT command returns the actual
measured output voltage in the same format as
set by the VOUT_MODE command.
SMBus transaction type
Read word
Number of data bytes
2
Table 29.
READ_IOUT
Command name
READ_IOUT
Command code
8Ch
Description
The READ_IOUT command returns the
measured output current in amperes.
SMBus transaction type
Read word
Number of data bytes
2
Table 30.
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READ_TEMPERATURE
Command name
READ_TEMPERATURE
Command code
8Dh
Description
Up to three temperature readings can be
returned for each device.
SMBus transaction type
Read word
Number of data bytes
2
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PMBus commands and source code
Table 31.
PMBUS_REVISION
Command name
PMBUS_REVISION
Command code
98h
Description
PMBUS_REVISION command stores or reads
the revision of the PMBus to which the device is
compliant.
SMBus transaction type
Read byte
Number of data bytes
1
Table 32.
MFR_ID
Command name
MFR_ID
Command code
99h
Description
The MFR_ID commands loads the unit with
ASCII characters that contain the manufacturer's
ID (name, abbreviation or symbol that identifies
the unit's manufacturer). This is typically only
done once at the time of manufacture.
SMBus transaction type
Read/Write block
Number of data bytes
7
Table 33.
MFR_MODEL
Command name
MFR_MODEL
Command code
9Ah
Description
The MFR_MODEL command loads the unit with
ASCII characters that contain the manufacturer's
model number. This is typically done once at the
time of manufacture.
SMBus transaction type
Read/Write block
Number of data bytes
6
Table 34.
MFR_REVISION
Command name
MFR_REVISION
Command code
9Bh
Description
The MFR_REVISION command loads the unit
with ASCII characters that contain the
manufacturer's revision number. This is typically
done once at the time of manufacture.
SMBus transaction type
Read/Write block
Number of data bytes
2
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PMBus commands and source code
Table 35.
MFR_LOCATION
Command name
MFR_LOCATION
Command code
9Ch
Description
The MFR_REVISION command loads the unit
with ASCII characters that contain the
manufacturer's revision number. This is typically
done once at the time of manufacture.
SMBus transaction type
Read/Write block
Number of data bytes
2
Table 36.
MFR_DATE
Command name
MFR_DATE
Command code
9Dh
Description
The MFR_DATE command loads the unit with
ASCII characters that identify the unit's date of
manufacture. This is typically done once at the
time of manufacture.
SMBus transaction type
Read/Write block
Number of data bytes
6
Table 37.
MFR_SERIAL
Command name
MFR_SERIAL
Command code
9Eh
Description
The MFR_SERIAL command loads the unit with
a serial number to uniquely identify the unit
SMBus transaction type
Read/Write block
Number of data bytes
6
Table 38.
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MFR_SPECIFIC_00
Command name
MFR_SPECIFIC_00
Command code
D0h
Description
The MFR_SPECIFIC_00 command provides
access control for NVM register writes.
SMBus transaction type
Read byte
Number of data bytes
1
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PMBus commands and source code
Table 39.
Command name
MFR_SPECIFIC_01
Command code
D1h
Description
The MFR_SPECIFIC_01 command provides
access control for configuration register writes.
SMBus transaction type
Read byte
Number of data bytes
1
Table 40.
3.2
MFR_SPECIFIC_01
MFR_SPECIFIC_02
Command name
MFR_SPECIFIC_02
Command code
D2h
Description
The MFR_SPECIFIC_02 is a manufacturer
defined command.
SMBus transaction type
Read byte
Number of data bytes
1
Source code
The source code is attached in the zip file along with the application note. This source code
is organized as shown below.
' Workspace directory
' Debug
' object files, list files, map files, executable files (.elf), hex code
(.s19)
' Sources
' Main.c: Contains main source code. In this file, PMBus interface functions
are
called (refer to section 3.3).
' Main.h: Contains prototype of all functions used in Main.c.
' PMBus.c: Contains functions for PMBus write and read operation. The data
length calculator function and I2C and Alert signal interrupt subroutines are also written inside this file.
' PMBus.h: Contains prototype of all functions and enumerated data
types used in PMBus.c.
' SMBus_Master.c: Contains source code for differnet SMBus master
transaction bus protocols.
' SMBus_Master.h: Contains prototype of all functions and enumerated data
types used in SMBus_Master.c.
' st72264g1.h: Contains register mapping for ST72F264G1 device.
' ST7_hr.h: Contains hardware register bit definitions for ST7 MCU
' ST7_Config.h: Contains compiler selection, peripheral register inclusion,
header files inclusion for linking, macros for assembly instructions
and Fcpu Definition.
' interrupt_vector.c: Contains general Interrupt vector table for ST7 devices
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PMBus commands and source code
3.3
AN2511
Example
This section explains how to use the PMBus driver. An example operation of write/ read
commands are shown.
/*****************************************************************************
COPYRIGHT 2005 STMicroelectronics
Source File Name : Main.c
Group
: IMS Systems Lab
Author
: Telecom Team
Date First Issued: 01/09/2006
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*THE SOFTWARE INCLUDED IN THIS FILE IS FOR GUIDANCE ONLY. STMicroelectronics
SHALL NOT BE HELD LIABLE FOR ANY DIRECT, INDIRECT OR CONSEQUENTIAL
DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM USE OF THIS SOFTWARE.
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*********************************Documentation**********************************
General Purpose - Contains main source code. In this file, the PMBus command files
are written.
******************************************************************************/
#include "ST7_config.h"
/* Fcpu defined as 8MHz */
#include "main.h"
/* Contains the global variables used in main.c */
#include "ST7_hr.h"
/* Contains the register and flags for ST7 */
extern volatile unsigned int SMB_TimeCount;
/* Time count variable */
#pragma space extern [] @tiny
/* To force following variables into short
addressing memory */
extern unsigned char Data_Buff [32] ;
/* Buffer to store data */
/* Variables to differentiate the different SMBus transaction types */
extern volatile unsigned char SMBus_Mode ;
extern volatile unsigned char SMB_Err_Status ;
/* Error status */
/* Master to address slave with this
address */
static volatile unsigned char PMBus_SlaveAdd = 0x80;
/* Master to address slave with this
address */
static volatile unsigned char PMBus_SlaveAdd = 0x80;
/*----------------------------------------------------------------------------ROUTINE NAME : Main
INPUT
: None
OUTPUT
: None
DESCRIPTION : Using this file, user can write/ read PMBus commands.
COMMENTS
: Programs jumpts into this routine when microcontroller is reset
-----------------------------------------------------------------------------*/
void main()
{
unsigned char temp ;
SMBs_Address_t PMBus_Err ; /* To check errors in PMBus communication */
/*----------------------- Port A configuration ----------------------------*/
PADDR &= (unsigned char)~PORTA_DEFAULT;
PADDR = PORTA_DEFAULT ;
/* Other pins configured as floating input */
PAOR = (unsigned char)(PORTA_DEFAULT) ;
/*----------------------- Port C configuration ----------------------------*/
PCDDR = CONTROL ;
/* PC0 floating input, others push pull output */
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PMBus commands and source code
PCOR = CONTROL ;
PCDR = CONTROL ;
/*----------------------- Alert Interrupt configuration ------------------------------*/
EnableInterrupts;
/* Resets interrupt mask */
MISCR1 = 0x10 ;
/* EI0 on falling edge low level for Alert interrupt */
/*---------------------PMBus communication configuration-------------------*/
while (1)
{
/* I2C configuration: ST7 I2C address 0x30, communication speed 100kHz */
PMBus_Init (SMBs_MISC, SLAVEADD, 0x40, 0x23);
/* Checking if an alert signal is received from slave */
if (SMBus_Mode & SMB_ARA)
{
/* ST7 I2C sends the alert response address to check which slave
alerted */
PMBus_Err = SMBm_ReceiveByte (ALERTRESPONSEADD, Data_Buff);
/* Alerted slave address will be used for any further communication */
PMBus_SlaveAdd = *Data_Buff ;
SMBus_Mode &= (unsigned char) ~SMB_ARA ;
}
Command_Code = 0x01;
/* User should enter the PMBus command code here */
PMBus_CommandWrite (Command_Code);
/* Writes data from Data_Buff */
Command_Code =
0x02;
/* User should enter the PMBus command code here */
/* Read data and store it in Data_Buff */
PMBus_CommandRead (Command_Code);
if (SMB_Err_Status)
{
errors */
SMB_Err_Status = I2CSR2 ;
SMB_Err_Status = 0 ;
}
}
}
3.4
/* I2C status register read to clear any
/* End of while (1) */
/* End of main */
Limitations
1.
The SMBus driver used in this application note is tested only for write word, read word
and write block protocols with PEC disabled.
2.
The SMBus driver doesn't meet the clock low extending feature of SMBus v1.1 due to
the limitation of the I2C peripheral.
3.
In case of PEC, when slave is acting as receiver, the ACK bit is not disabled if the PEC
received from master transmitter is different from slave. It is stored in the user address
as the last byte. It is the responsibility of the user to check the master PEC with the
slave PEC to decide on data validity.
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PMBus interfacing results
4
AN2511
PMBus interfacing results
This section describes the results of interfacing the demonstration board with Artesyn and
SiLabs modules.
4.1
Interfacing with Artesyn module
The following table shows the different PMBus commands and ST demonstration board
results compared to the Artesyn DPL20C PMbus module.
Table 41.
Command
code
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PMBus interfacing with Artesyn module: results
PMBus command
SMBus transaction
type
Number
of data
bytes
Data
(Si8250)
Data
(ST7)
01
OPERATION
Read/ write byte
1
80
80
02
ON_OFF_CONFIG
Read/ write byte
1
14
14
03
CLEAR_FAULTS
Send byte
0
12
RESTORE_DEFAULT_
ALL
Send byte
0
15
STORE_USER_ALL
Send byte
0
20
VOUT_MODE
Read/ write byte
1
1A
1A
21
VOUT_COMMAND
Read/ write word
2
00 60
00 60
24
VOUT_MAX
Read/ write word
2
01 60
01 60
25
VOUT_MARGIN_HIGH
Read/ write word
2
00 6 A
00 6 A
26
VOUT_MARGIN_LOW
Read/ write word
2
00 56
00 56
42
VOUT_OV_WARN_LIM
IT
Read/ write word
2
00 6E
00 6E
43
VOUT_UV_WARN_LIM
IT
Read/ write word
2
00 56
00 56
46
IOUT_OC_FAULT_LI
MIT
Read/ write word
2
00 19
00 19
4A
IOUT_OC_WARN_LIM
IT
Read/ write word
2
00 17
00 17
4F
OT_FAULT_LIMIT
Read/ write word
2
00 78
00 78
50
OT_FAULT_RESPONS
E
Read/ write byte
1
B1
B1
51
OT_WARN_LIMIT
Read/ write word
2
00 6E
00 6E
60
TON_DELAY
Read/ write word
2
00 00
00 00
61
TON_RISE
Read/ write word
2
00 0A
00 0A
64
TOFF_DELAY
Read/ write word
2
00 00
00 00
65
TOFF_FALL
Read/ write word
2
00 00
00 00
Doc ID 13286 Rev 2
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PMBus interfacing results
Table 41.
Command
code
4.2
PMBus interfacing with Artesyn module: results (continued)
PMBus command
SMBus transaction
type
Number
of data
bytes
Data
(Si8250)
Data
(ST7)
78
STATUS_BYTE
Read byte
1
41
41
79
STATUS_WORD
Read word
2
00 41
00 41
7A
STATUS_VOUT
Read byte
1
00
00
7B
STATUS_IOUT
Read byte
1
00
00
7D
STATUS_TEMPERATU
RE
Read byte
1
00
00
80
STATUS_MFR_SPECI
FIC
Read byte
1
02
02
8B
READ_VOUT
Read word
2
00 01
00 01
8C
READ_IOUT
Read word
2
D7 C3
D7 C3
8D
READ_TEMPERATURE
Read word
2
00 20
00 1D
98
PMBUS_REVISION
Read byte
1
01
01
99
MFR_ID
Read block
7
41 52 54
41 52 54 45
45 53 59
53 59 4E
4E
9A
MFR_MODEL
Read block
6
44 50 4C 32 44 50 4C
30 43
32 30 43
9B
MFR_REVISION
Read/ write block
2
31 02
31 41
9C
MFR_LOCATION
Read/ write block
2
5A 02
5A 53
9D
MFR_DATE
Read/ write block
6
32 34 30 33 32 34 30
36 06
33 36 36
9E
MFR_SERIAL
Read/ write block
6
31 32 33 34 31 32 33
35 06
34 35 36
D0
MFR_SPECIFIC_00
Read byte
1
28
28
D1
MFR_SPECIFIC_01
Read byte
1
10
10
D2
MFR_SPECIFIC_02
Read byte
1
0A
0A
Interfacing with SiLabs module
The following table shows the different PMBus commands and ST demonstration board
results compared to Silicon Labs Si8250 - TB module.
Table 42.
Command
code
PMBus interfacing with SiLabs module: results
PMBus command
SMBus transaction
type
Number
of data
bytes
Data
(Si8250)
Data
(ST7)
01
OPERATION
Read/ write byte
1
C0
C0
02
ON_OFF_CONFIG
Read/ write byte
1
1E
1E
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PMBus interfacing results
Table 42.
Command
code
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PMBus interfacing with SiLabs module: results (continued)
PMBus command
SMBus transaction
type
Number
of data
bytes
Data
(Si8250)
Data
(ST7)
03
CLEAR_FAULTS
Send byte
0
12
RESTORE_DEFAULT_ALL
Send byte
0
15
STORE_USER_ALL
Send byte
0
20
VOUT_MODE
Read/ write byte
1
11
11
21
VOUT_COMMAND
Read/ write word
2
7F F6
7F F6
24
VOUT_MAX
Read/ write word
2
89 94
89 94
25
VOUT_MARGIN_HIGH
Read/ write word
2
00 6A
00 6A
25
VOUT_MARGIN_HIGH
Read/ write word
2
86 5C
86 5C
26
VOUT_MARGIN_LOW
Read/ write word
2
79 90
79 90
42
VOUT_OV_WARN_LIMIT
Read/ write word
2
89 94
89 94
43
VOUT_UV_WARN_LIMIT
Read/ write word
2
76 58
76 58
4F
OT_FAULT_LIMIT
Read/ write word
2
EB 20
EB 20
50
OT_FAULT_RESPONSE
Read/ write byte
1
00
00
51
OT_WARN_LIMIT
Read/ write word
2
EA D0
EA D0
60
TON_DELAY
Read/ write word
2
00 0A
00 0A
61
TON_RISE
Read/ write word
2
00 32
00 32
64
TOFF_DELAY
Read/ write word
2
00 0A
00 0A
65
TOFF_FALL
Read/ write word
2
00 C8
00 C8
78
STATUS_BYTE
Read byte
1
04
04
79
STATUS_WORD
Read word
2
00 04
00 04
7A
STATUS_VOUT
Read byte
1
00
00
7B
STATUS_IOUT
Read byte
1
00
00
7D
STATUS_TEMPERATURE
Read byte
1
20
20
80
STATUS_MFR_SPECIFIC
Read byte
1
00
00
8B
READ_VOUT
Read word
2
80 4E
80 76
8C
READ_IOUT
Read word
2
D7 C3
00 00
8D
READ_TEMPERATURE
Read word
2
EF 56
EF 56
98
PMBUS_REVISION
Read byte
1
00
00
D0
MFR_SPECIFIC_00
Read byte
1
67
67
D1
MFR_SPECIFIC_01
Read byte
1
EF
EF
D2
MFR_SPECIFIC_02
Read byte
1
08
08
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5
PMBus demonstration board
PMBus demonstration board
To show the features of the ST7 I2C working as a PMBus, a demonstration board is
available on request. Please contact the nearest ST office to get this board. The evaluation
board has an ST72F264G1 MCU that has 4 KBytes Flash memory. All PMBus
functionalities are not shown, as this evaluation board has hyperterminal interface which
requires lot of messages to be stored in program memory.
5.1
System requirements
In order to use the PMBus demonstration board with the Windows operating system. The
PC should support hyperterminal software and RS232 communication using DB9
connector.
5.2
Software setup
To configure the PC hyperterminal software, the user should follow the steps as mentioned
below.
1.
Click on Start -> Programs -> Accessories -> Communications -> HyperTerminal
as shown below.
Figure 6.
PC hyperterminal application
2.
Select the correct port in which RS232 (9-pin cable) is connected (refer to Section 3).
3.
Configure the following baud rate (bits per second) in hyperterminal: File -> Properties
-> Connect to -> Configure. If the user configures any baud rate other than 38400,
then RS232 communication fails.
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PMBus demonstration board
Figure 7.
4.
5.3
Baud rate configuration
Configure the following settings in hyperterminal: File -> Properties -> Settings ->
ASCII setup
Figure 8.
5.
AN2511
Hyperterminal settings - ASCII setup configuration
Press call in hyperterminal to establish a connection with the board.
Hardware setup
To configure the hardware board, the user should follow these steps:
1.
28/43
Jumper settings: There are four jumpers (JP1, JP2, JP3 and JP4) available on the
board. The detail of these connectors is as follows:
a)
JP1: JP1 pins should be connected using the jumper if there is no pull-up
connected in the clock line of the I2C bus. Once connected, the I2C clock line is
pulled up with a resistor value of 4.7 kΩ.
b)
JP2: JP2 pins should be connected using the jumper if there is no pull-up
connected in the data line of the I2C bus. Once connected, the I2C data line is
pulled up with a resistor value of 4.7 kΩ.
c)
JP3: JP3 is used to select the clock source for the ST7 microcontroller. From the
JP3 side, if the jumper is connected between pins 1 and 2 then the application
Doc ID 13286 Rev 2
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PMBus demonstration board
runs using the resonator clock (16 MHz). If the jumper is connected between pins
2 and 3 then the application is stopped and ST7 MCU can be re-programmed.
d)
2.
JP4: JP4 is used to select the power supply as described below. From the JP4
side, if the jumper is connected between pins 2 and 3 then the application runs
using the direct supply given from `POWER' connector. If the jumper is connected
between pins 1 and 2 then the application runs using the DC adapter supply given
from J1.
Power settings: The demonstration board can be powered by one of the following
options:
a)
DC adapter: Connect a DC adapter to J1. The DC adapter should supply a
minimum of 7 V and maximum of 18 V, 1 A. This supply is regulated to 5 V supply
using an L7805 regulator.
b)
Regulated supply: The user can use a direct 3 V to 5 V supply. The supply and
Gnd points should be connected to the `POWER' connector pins 1 and 2. Here,
`POWER' connector pin 1 is referred from the JP4 jumper side (from the right
side).
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Using the demonstration board
6
AN2511
Using the demonstration board
After installing the setup as explained in Section 1, the following message appears in
hyperterminal.
Figure 9.
Hyperterminal message to show company name and selection of
communication speed
If there is any problem in getting the message, press the switch provided in the
demonstration board. This switch re-starts the application.
6.1
Normal operation
The following sections explain how to initiate PMBus communication and how to read/ write
PMBus commands with hyperterminal.
6.1.1
Selection of communication speed
After the message appears as shown in Figure 9, the user should enter 1 or 2 to select the
PMBus communication speed as 100 kHz or 400 kHz respectively. The default speed value
selected is 100 kHz.
If the user enters any other value other than 1 and 2, the previous speed value is retained.
6.1.2
Selection of packet error checking
After the message appears as shown in Figure 10, the user should enter 1 or 2 to enable
PEC and disable PEC respectively. If PEC is enabled, all address, command code and data
communications are checked through CRC-8 check. The default PEC value is PEC
disabled.
If the user enters any other value other than 1 and 2, the previous speed value is retained.
Figure 10. PEC selection
6.1.3
Selection of slave address
The user should enter the slave address of the PMBus device. The slave address should be
in hexadecimal format. The slave addresses of different competitor’s module are given
below. Artesyn DPL20C module: 0x30 SiLabs Si8250-TB module : 0x80.
The slave address could change from one device to another device. The user must refer to
the product datasheet and development kit documents to decide on the slave address. An
example entry of slave address with Artesyn DPL20C module is shown below.
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Using the demonstration board
Figure 11. Slave address entry message
If the user enters a wrong slave address then one of the following error messages shown in
Figure 12 or Figure 13 appears.
Figure 12. Wrong slave address entry - response 1
Figure 13. Wrong slave address entry - response 2
6.1.4
Selection of read/write mode
Data can be written into or data can be read back from the PMBus salve device connected.
The following figure provides the key option to select one of the modes.
Figure 14. Options to select read/ write mode
6.1.5
Single read mode
The user can press 1 to select read mode. Then the user can enter any command code with
reference to Section 3 to read byte/ word/ block of data. An example of this is shown below.
Figure 15. Single read operation
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Using the demonstration board
6.1.6
AN2511
Continuous read mode
The user can press 0 to read all PMBus commands. The lists of supported commands are
shown in the following figure.
Figure 16. Continuous read operation
Command codes 0xD0, 0xD1 and 0xD2 are not supported in continuous read mode. If the
user wants to read these commands, they can be read by using single read mode.
6.1.7
Write mode
The user can press 2 to select write mode. After the following figure appears, the user can
enter any command code with reference to Section 2.1 on page 8 to write byte/ word/ block
of data.
Figure 17. Write mode command code entry message from hyperterminal
Then the user can enter any command code with reference to Section 4 to write byte/ word/
block of data. The user can enter data after the following message.
Figure 18. Write mode data entry message from hyperterminal
Data should be entered in hex format. If the user wants to enter date/ serial numbers, they
should be entered in ASCII format.
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Doc ID 13286 Rev 2
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Using the demonstration board
For example, to enter a date as “15 -12-1991”, then data should be entered as
313531323931 (where 31h=ASCII ”1”, 35h=ASCII “5”, etc., and the date will read “151291”).
An example of this operation is shown below.
Figure 19. Write mode operation example
When reading back the date written using single read commands, the following message is
displayed:
Figure 20. Read operation to check data writing
6.1.8
Group command
The user can press 3 to select group command mode. In this demonstration board, the user
can write multiple commands for multiple slave addresses.
After Figure 21 appears, the user can enter any command code and data with reference to
Section 3.1: PMBus commands to write byte/ word/ block of data. The user can enter 5
commands and data for the group command. If the user wants to write less than 5
commands, the user can press * to terminate the group command operation.
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Using the demonstration board
AN2511
Figure 21. Group command code entry message from hyperterminal
An example of this operation is shown below.
Figure 22. Group command operation example
6.2
Error conditions
The following error conditions may be encountered during PMBus communication.
6.2.1
Invalid command code
If the user enters a command code that is not available in the list or enters an incorrect
option to select read/write options, the following error message appears:
Figure 23. Invalid command message
An example is shown in Figure 24.
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Using the demonstration board
Figure 24. Example of invalid command
6.2.2
Communication timeout
This error appears when the PMBus communication fails due to one of the following
reasons:
●
The slave device doesn’t acknowledge the master
●
The clock low interval exceeds the value of TTIMEOUT,MIN as defined by (SMBus
Specification 1.1)
●
TLOW:SEXT and TLOW:MEXT conditions are not met
●
Bus error or arbitration errors in PMBus communication
In these conditions, the following error message appears:
Figure 25. Communication timeout message
Doc ID 13286 Rev 2
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Doc ID 13286 Rev 2
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7
40
Hardware description
AN2511
Hardware description
This section provides schematics, BOM (bill of materials), layout and picture of the
demonstration board.
Schematic and layout
The following figures show the schematic and layouts of the demonstration board.
Figure 26. Demonstration board schematic
!-V
AN2511
Hardware description
Figure 27. Top view layout of the demonstration board
Figure 28. Bottom view layout of the demonstration board
Doc ID 13286 Rev 2
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Bill of materials (BOM)
AN2511
7.2
The following table shows the BOM of the demonstration board.
Table 43.
Table 43:
Bill of material
Doc ID 13286 Rev 2
Package
Manufacturer
Capacitors: C2, C3, C9, C10, C11, C12, C13
100 nF
805
Any
Capacitors: C7, C8
10 nF
805
Any
Capacitors: C5, C6
10 pF
805
Any
Capacitors: C1
330 nF
805
Any
Polarized capacitor (Axial): C4
100 µF/ 10 V
RB-5.5
Any
Resistors: R1, R2, R3
4.7 kΩ
805
Any
Resistors: R4, R5
100 Ω
805
Any
Resistors: R6
220 Ω
805
Any
Resistors: R7
10 kΩ
805
Any
Connector: TP3
CON1
SIP-1
Any
Connectors: J2, J3, J4, JP1, JP2, POWER
CON2
SIP-2
Any
Connectors: JP3, JP4
CON3
SIP-3
Any
Connector: J5
CON4
SIP-4
Any
Connector J7
CON7
SIP-7
Any
9 pin female RS232 connector: J6
DB9
DB9/F
Crystal: Y1
16 MHz (KDS)
XTAL-1
Any
Header: CON1
ICC
IDC-10B
Any
Power Jack connector: J1
JACK
TAP_2.5 mm
Regulator: U1
L7805CD2T-TR
TO-220
STMicroelectronics
SMD LED: D1
SMD LED
LED-SMD
Faichild
Manufacturer’s
ordering code /
orderable part
number
Supplier
GM (801-036)
GM: K375A
L7805CD2T-TR
Hardware description
38/43
Reference
Value / generic part
number
Bill of material (continued)
Reference
Value / generic part
number
Package
Manufacturer
Manufacturer’s
ordering code /
orderable part
number
MCU U2
ST72F264G1M6
SOL-28
STMicroelectronics
ST72F264G1M6
RS232 level translator: U3
ST3232CTR
SO-16
STMicroelectronics
ST3232CTR
Switch S1
TACT SWITCH
PUSH-4
Any
Diode: D2
1N5817
DO41
STMicroelectronics
ZENER diode: ZD1
SMAJ
TO220
STMicroelectronics
Supplier
Hardware description
39/43
Table 43.
Doc ID 13286 Rev 2
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Hardware description
7.3
AN2511
Demonstration board photo
The following figure shows the picture of the demonstration board.
Figure 29. STEVAL-ISQ002V1
40/43
Doc ID 13286 Rev 2
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Configuration
Appendix A
A.1
Configuration
RS232 configuration
The following figure shows the pin description of the RS232 D9 connector.
Figure 30. Pin description of RS232 D9 connector
Doc ID 13286 Rev 2
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Revision history
AN2511
Revision history
Table 44.
Document revision history
Date
Revision
17-Apr-2007
1
Initial release.
2
– Modified: Figure 9, 10, 16, 17, 18, 19, 20, 23, 24, 25, 26, 29,
Table 43
– Added: Figure 27, 28
– Minor text changes
25-Aug-2010
42/43
Changes
Doc ID 13286 Rev 2
AN2511
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