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![• Commands Will Return Two Values
– An Accumulated Energy Reading (“Watt-Samples”)
– Current Number Of Power Samples
Discrete Time Power Calculation
Power Calculation
27
• Discrete Time Power Calculation
1 1
1 1
[ ] [ ] [ ]
N N
AVE
n n
P p n v n i n
N N
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PMBus Specification Rev 1.2 Presentation 20100228.pdf
- 1. PMBus™ – Coming ToA Server Near You Coming To A Server Near You Bob White Chair, PMBus™ Specification Working Group bob.white@ieee.org 1 www.pmbus.org
- 2. Presentation Overview • PMBus™Specification And Application Profiles • PMBus In Today’s Servers • PMBus In Next Gen Servers 2 • New Energy Reading Commands • Clarification Of Status Bits And SMBALERT# Signal • Other Coming Updates
- 3. Disclaimer Any Information AboutThe Upcoming 3 Any Information About The Upcoming Revision Of The PMBus Specification And Application Profiles Is Preliminary And May Change Without Notice.
- 4. The PMBus Specification •Includes – How Devices Communicate – Commands And Data PMBus Spec 4 Commands And Data • Does Not Include – Application Specific Information – Required Commands – Tolerances Revision 1.2 Coming Soon
- 5. Application Profiles • Includes –Required Commands – Required Data Formats App Profile 5 Formats – Required Data Ranges – Tolerances Application Profile For Server Power Coming Soon After Specification Revision 1.2
- 6. Server Power ApplicationProfile • Addressing • Hardware • Data Formats – Accuracy • Status Commands • Limit Commands • Default Limits • Manufacturer 6 y – VOUT_MODE – Sensor – Formatting Tables • Monitoring Power/Current/Voltage – Sensor Sampling • Thermal Management Manufacturer Controlled Limits • Faults And Error Correction • Capability And Inventory Reporting • Write Protection • Interrupts
- 7. PMBus In AServer MAN System Applications Node Manger Server Management 7 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply WS-M
- 8. PMBus In AServer MAN System Applications Node Manger Server Management Baseboard Management Controller 8 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply WS-M
- 9. PMBus In AServer MAN System Applications Node Manger Server Management PMBus 9 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply WS-M
- 10. PMBus In AServer MAN System Applications Node Manger Server Management PMBus Is Not Used To Communicate Outside The Server 10 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus WS-M
- 11. PMBus In DataCenter Data Center Applications DMTF SMASH 11 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus WS-MAN System Applications SMASH
- 12. PMBus In DataCenter Data Center Applications • Charge Back • Track Energy Consumption • Thermal Mgt • Protect Against Hot Spots • Circuit Mgt 12 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus WS-MAN • Circuit Mgt • Protect Against Breaker Overload System Applications
- 13. PMBus In ANext Gen Server Val e Add Additional System Management Functions 13 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus Value Add Processor
- 14. PMBus In ANext Gen Server Val e Add Multiple Master Bus 14 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus Value Add Processor
- 15. Multiple Output PowerSupplies 15
- 16. Multiple Output PowerSupplies PAGE Command Sets The Switch 16
- 17. Multiple Output PowerSupplies Step 1: Set The Desired Output (PAGE) Step 2: Send A Command To That Output 17
- 18. Potential Conflict Val eAdd 1. VAP Sets PAGE 2. BMC Sets A Different PAGE 3. VAP Sends A Command – To The Wrong Output! 18 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus Value Add Processor
- 19. PAGEPLUS • New Command:PAGE PLUS • Transmit In One Bus Transaction – Device Address S t Th PAGE 19 – Set The PAGE – Send A Command To That Page – Write Or Read Data Related To That Command ADDRESS PAGE CMD COMMAND DATA (R/W)
- 20. Another Potential Conflict Vale Add 1. BMC Reads Status 2. BMC Clears Status 3. VAP Can’t Know What Happened 20 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus Value Add Processor
- 21. Another Potential Conflict Vale Add Why Can’t These Two Processors Talk To Each Other? 21 Server Motherboard BMC Sub Systems IPMI Power Supply Power Supply PMBus Value Add Processor
- 22.
- 23. Bits Set Together/ClearedIndividually STATUS_x PAGE M Cleared By One Master 23 STATUS_x PAGE N Cleared By The Other Master
- 24. Reading Input AndOutput Power • PMBus Has READ_POUT And READ_PIN Commands • But… G tti G d V l F P I P bl ti 24 • Getting Good Values For Power Is Problematic • Issues – Averaging Time – Data Age – Averaging Calculation Methods • OEMS Are Looking For Accuracy Of 1-2%
- 25. Reading Input AndOutput Power • PMBus Has READ_POUT And READ_PIN Commands • But… G tti G d V l F P I P bl ti 25 • Getting Good Values For Power Is Problematic • Issues – Averaging Time – Data Age – Averaging Calculation Methods • OEMS Are Looking For Accuracy Of 1-2% “Sampling And Averaging Considerations For Measuring AC Input Power” APEC 2009
- 26. READ_EIN And READ_EOUT •Revision 1.2 Will Have Two New Commands: READ_EIN And READ_EOUT • Attempt Is To Make Reporting Of Power I d d t Of PMB D i Ch t i ti 26 – Independent Of PMBus Device Characteristics – Put Computation Burden On Host – Put Time Keeping Burden On Host
- 27. • Commands WillReturn Two Values – An Accumulated Energy Reading (“Watt-Samples”) – Current Number Of Power Samples Discrete Time Power Calculation Power Calculation 27 • Discrete Time Power Calculation 1 1 1 1 [ ] [ ] [ ] N N AVE n n P p n v n i n N N
- 28. Power Calculation • HostKeeps At Least The Last Values Returned – With Time Stamp Information If Needed – Rollover Tracking Are The Host’s Responsibility Host Retrieves Accumulator And Sample Count 28 • Host Retrieves Accumulator And Sample Count When It Wants • Host Calculates The Average Power Since The Last Reading By: Latest Accumulator Count – Previous Accumulator Count Latest Sample Count – Previous Sample Count AVERAGE P
- 29. Conceptual Implementation Vin Clock Multiplier A/D ScaleBy LSB_V & LSB_I Accumulator (40 Bits?) Data Formatter Packet 29 Iin Clock A/D Sample Counter (24 Bits) Maker/ Bus Interface Clock
- 30. Clarify Status Bits/SMBALERT# •Comments Received That Specification Is Not Clear On How Status Bits Are: – Set Cleared 30 – Cleared – Interact With SMBALERT# Signal
- 31. LATCH SET Q Bit InSTATUS_BYTE/ STATUS_WORD Register Bit In STATUS_X Register Event Detector Output Other Status Bits That Can Set The Same Bit In STATUS_BYTE/ STATUS_WORD Conceptual Schematic Looking At Using A Conceptual Schematic To Convey F nctionalit 31 CLR SMBALERT# Circuit SMBALERT_MASK Bit CLEAR_FAULTS Write 1 To Status Register Bit Device Address Sent In Response To Receiving A Read To The Alert Response Address While SMBALERT# Asserted Other Status Bits That Can Cause SMBALET# To Be Asserted CLR SMBALERT# PAGE Selected Functionality
- 32. LATCH SET Q Bit InSTATUS_BYTE/ STATUS_WORD Register Bit In STATUS_X Register Event Detector Output Other Status Bits That Can Set The Same Bit In STATUS_BYTE/ STATUS_WORD Conceptual Schematic New Clear Individual Status Bits And Registers 32 CLR SMBALERT# Circuit SMBALERT_MASK Bit CLEAR_FAULTS Write 1 To Status Register Bit Device Address Sent In Response To Receiving A Read To The Alert Response Address While SMBALERT# Asserted Other Status Bits That Can Cause SMBALET# To Be Asserted CLR SMBALERT# PAGE Selected
- 33. LATCH SET Q Bit InSTATUS_BYTE/ STATUS_WORD Register Bit In STATUS_X Register Event Detector Output Other Status Bits That Can Set The Same Bit In STATUS_BYTE/ STATUS_WORD Conceptual Schematic New SMBALERT_MASK 33 CLR SMBALERT# Circuit SMBALERT_MASK Bit CLEAR_FAULTS Write 1 To Status Register Bit Device Address Sent In Response To Receiving A Read To The Alert Response Address While SMBALERT# Asserted Other Status Bits That Can Cause SMBALET# To Be Asserted CLR SMBALERT# PAGE Selected
- 34. Other Changes • NowBased On SMBus V2.0 • Bus I/O High Impedance When Device Is Off • Group Protocol PEC Clarified 34 • IOUT_CAL_GAIN Updated • MFR_MAX_TEMP_1,2,3 Command Not The Complete List!
- 35. Acknowledgment Thanks To BrianGriffith Of Intel Corporation 35 p For Contributions On “PMBus In A Server”, “PMBus In the Data Center” And Server Power Application Profile
- 36.