ICD Software Protocol.pdf

STUB

Version 1.0

Interface Control Document for Software Protocol

August 2021

Interface Control Document ii August 2021

Version 1.0

Revision History

Date Version Description Author

8/9/2021 Draft

Interface Control Document iii <Month> <Year>

Table of Contents

1. Introduction

1.1. Purpose

1.2. Scope

1.3. System Identification

2. Interface Definition

2.1. System Overview

2.2. Interface Overview

2.3. Data Transfer

2.4. Transaction Types

2.5. Data Exchanges

2.6. Communications Methods

3. Interface Requirements .......................... Error! Bookmark not defined.

3.1. Interface #1 Requirements .................................. Error! Bookmark not defined.

3.2. Interface #1 Requirements .................................. Error! Bookmark not defined.

3.2.1. Interface Processing Time Requirements . Error! Bookmark not defined.

3.2.2. Data Assembly Characteristics

3.2.3. Communication Methods

3.2.4. Interface Initiation

3.2.5. Flow Control

3.2.6. Physical Requirements ............................... Error! Bookmark not defined.

3.2.7. Structural Requirements ............................. Error! Bookmark not defined.

3.2.8. Mechanical Requirements ........................... Error! Bookmark not defined.

3.2.9. Electrical Requirements .............................. Error! Bookmark not defined.

3.2.10. Thermal Requirements ................................ Error! Bookmark not defined.

3.2.11. Special Fluid Requirements ........................ Error! Bookmark not defined.

3.2.12. Signal Requirements ................................... Error! Bookmark not defined.

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1. Introduction This Interface Control Document (ICD) describes the relationship between the Small Tactical Universal Battery (STUB) and the end user device (EUD) in terms of data items, messages, protocols observed, and sequencing of events pertaining to the 5 Ampere capability.

1.1. Purpose

This document will thoroughly desrcribe the software protocol and physical requirement needed to establish a 5 Ampere contract using an unstructured vendor defined message (UVDM) in accordance with the USB PD 3.1 Specification or later. In addition to the 5A contract, this document decribes the software protocol to extract SMBUS data through standard USB PD messaging.

1.2. Scope

This ICD specifies the relationship between the two use cases, STUB to STUB and STUB to EUD, pertaining to the 5 Ampere UVDM. This document describes protocol and physical parameters.

1.3. System Identification

All STUBs and EUDs capable of a 5 Ampere contract must transmit the Vendor Identification Code (VID), 2C15h. Once VID has passed the CRC, the Source Capabilities (Caps) will be rebroadcasted with expanded current for contract.

2. Interface Definition All connections and interfaces will be in accordance with the USB PD 3.1 Specification or later.

2.1. System Overview

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2.2. Interface Overview

The default state of STUB is DFP. Once the UFP which is the EUD requests the PDO, there is a good CRC acknowledgment from the DFP and then it will send out PS RDY message meaning the DFP is ready to supply the requested PDO voltage and current. If the attached device needs 5A it will initiate a DR SWAP to become the DFP. Once the device is the DFP it will send out the UUVDM with a vendor ID 2C15. If the attached STUB is 2523 (6 cell) or 2524 (8 cell) it will re-broadcast the PDOs with greater than 3A. Once the new Source Caps are advertised by the STUB, the device will re-request the new PDO. PD contract ought to resemble figure 1 and figure 2.

Figure 1

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Figure 2

2.3. Data Transfer

All data transfers will be in accordance with the USB PD 3.1 Specification or later.

2.4. Transaction Types

All transaction types will be in accordance with the USB PD 3.1 Specification or later.

2.5. Data Exchanges

In addition to the data exchanges in accordance with the USB PD 3.1 Specification or later, SMBus v1.1 has been added. The compatibility list is below.

SMBus

USB PD Comments

Command Code

Function Name Spec Section

Message Name Field 0x08 Temperature 6.5.2.1 SOP Status Internal Temp SMBus Range: 0-6553.5 K, units of 0.1K; USB PD Range: 2-255 C, units of C (setting Internal Temp to 1 means temperature <2 C) 0x09 Voltage 6.5.10 PPS_Status Output Voltage SMBus Range: 0-65535 mV, units of mV; USB PD Range: 0-1310680 mV, units of 20mV 0x0a Current 6.5.10 PPS_Status Output Current SMBus Range: -32768 to 32767 mA, units of mA; USB PD Range: 0-12700 mA, units of 50mA, seems to only be positive

6.4.5 Battery_Status Battery Info In USB PD, instead of using positive or negative current, charge/discharge status is indicated here 0x0f RemainingCapacity 6.4.5 Battery_Status Battery Present Capacity SMBus value is predicted, unsure if USB PD's is too; USB PD units are only in 10mWh, both have same range of 0-65535 10mWh

USB PD does not have some alarms, only has over temperature alarm; has overcurrent/overvoltage alarms that SMBus doesn't have

0x10 FullChargeCapacity 6.5.5 6.5.2.1

Battery_CapabilitiesBattery Last Full Charge Capacity SOP Status Event Flags, Temperature Status

0x16 BatteryStatus 6.4.5 Battery_Status Battery Info Battery Info does not say fully charged or fully discharged, only charging/discharging/idle 0x18 DesignCapacity 6.5.10

6.5.5 PPS_Status Real Time Flags Battery_Capabilities Battery Design Capacity

Additional over temperature warning here, not sure what the difference is between this and SOP_Status over temp alarm USB PD units are only in 10mWh, both have same range of 0-65535 10mWh

0x19 DesignVoltage 6.4.1.2.4 Source_Capabilities Maxmimum Voltage SMBus Range: 0-65535 mV, units of mV; USB PD Range: 0-51200 mV, units of 50mV 0x1a SpecificationInfo 0x1b ManufactureDate

6.2.1.1 6.5.7

Message Header Specification Revision Manufacturer_Info Manufacturer String

No correspondence between SMBus and USB PD revision numbers; USB PD does not have VScale or IPScale USB PD has no dedicated field for date, but we could put it in the manufacturer string

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0x1c SerialNumber 6.5.7 6.5.7

Manufacturer_Info PID Manufacturer_Info VID

PID = Product ID; Both hold a 16-bit number USB PD Vendor ID number could be converted to a manufacturer name

0x20 ManufacturerName 6.5.7 Manufacturer_Info Manufacturer String Could put string representing manufacturer name here too 0x21 DeviceName 6.5.7 Manufacturer_Info PID USB PD has no dedicated field for device name, but we could convert it from the PID number 0x22 DeviceChemistry 6.5.8 Manufacturer_Info PID USB PD has no dedicated field for device chemistry, but we could convert it from the PID number 0x14 ChargingVoltage

2.6 Operational Overview In USB PD, this is handled by contract negotiation

0x15 ChargingCurrent 0x16 AlarmWarning 6.4.6 Alert Type of Alert USB PD does not have the exact same set of alerts as SMBus's alarms

Key for row colors White = Fully/mostly compatible Orange = Partially compatible

2.6. Communications Methods

Standard PD messaging in accordance with the USB PD 3.1 Specification or later.

2.6.1. Data Assembly Characteristics

All data must be assembled in accordance with the USB PD 3.1 Specification or later

2.6.2. Communication Methods

All communication methods must be in accordance with the USB PD 3.1 Specification or later

2.6.3. Interface Initiation

Please refer to USB PD 3.1 Specification or later.

2.6.4. Flow Control

Please refer to USB PD 3.1 Specification or later.