External RFCOMM1.1v16.4.4 Software Release Note

c02-srn-005Pa 

BlueCore 2-External 

© Copyright CSR 2003 

This material is subject to CSR’s non-disclosure agreement. 

RFCOMM1.1v16.4.4 

Software Release Note 

February 2003 

CSR 

Unit 400 Cambridge Science Park 

Milton Road 

Cambridge 

CB4 0WH 

United Kingdom 

Registered in England 3665875 

Tel: +44 (0)1223 692000 

Fax: +44 (0)1223 692001 

www.csr.com

Contents 

bc02-srn-005Pa 



Contents 

1 Introduction .............................................................................................................................................3 

2 Firmware Identification ............................................................................................................................4 

3 Target Hardware ......................................................................................................................................5 

4 Qualification Information.........................................................................................................................6 

5 Functional Restrictions ...........................................................................................................................7 

5.1 4Mbit Variant...................................................................................................................................7 

5.2 8Mbit Variant...................................................................................................................................7 

6 Known Issues ..........................................................................................................................................8 

7 Changes Relative to RFCOMM1.1v15.2.1 Release...................................................................................9 

8 Issues Resolved Since RFCOMM1.1v15.2.1 Release ............................................................................10 

9 Piconet Support.....................................................................................................................................11 

10 Testing ...................................................................................................................................................12 

11 BlueLab Compatibility ...........................................................................................................................13 

12 RFCOMM Throughput Measurements ...................................................................................................14 

13 Host-to-BlueCore RFCOMM Flow Control .............................................................................................21 

13.1 Background ..................................................................................................................................21 

13.2 Flow Control Layer ........................................................................................................................21 

13.3 Initialisation...................................................................................................................................22 

13.4 Practical Implications of the New Mechanism.................................................................................22 

13.5 H4 ..............................................................................................................................................22 

14 Document References ...........................................................................................................................23 

Acronyms and Definitions............................................................................................................................24 

Record of Changes.......................................................................................................................................26 

List of Figures 

Figure 12.1: RFCOMM Throughput (Master to Slave) vs. Frame Size...............................................................15 

Figure 12.2: RFCOMM Throughput (Slave to Master) vs. Frame Size...............................................................16 

Figure 12.3: RFCOMM Equivalent Baud Rate (Master to Slave) vs. Frame Size ..............................................17 

Figure 12.4: RFCOMM Equivalent Baud Rate (Slave to Master) vs. Frame Size ...............................................18 

Figure 12.5: RFCOMM Frame-Rate (Master to Slave) vs. Frame Size..............................................................19 

Figure 12.6: RFCOMM Frame-Rate (Slave to Master) vs. Frame Size..............................................................20 

Figure 13.1: Flow Control Layer ......................................................................................................................21 

List of Tables 

Table 2.1: Available Firmware Variants..............................................................................................................4 

Table 6.1: Known Issues...................................................................................................................................8 

Table 11.1: BlueLab Compatibility...................................................................................................................13 

Page 2 of 26 

BlueCore 2-External RFCOMM1.1v16.4.4 Software Release Note

1 Introduction 




Introduction 

This document describes the RFCOMM1.1v16.4.4 release of software for CSR's BlueCore2 Bluetooth chip. 

This firmware is based upon the HCIStack1.1v16.4 release. 

RFCOMM firmware exposes application programming interfaces (API) to L2CAP, Service Discovery Protocol 

(SDP), RFCOMM and Device Manager (DM) functionality. These are described in the referenced document 

[BSUG]; background information on Bluetooth and its upper layers can be found in [BT]. The firmware also 

contains a Virtual Machine (VM), which may be used to run applications. The BlueLab software development 

kit (SDK), which allows applications to be developed, is available separately. This release may be used for VM 

applications developed using BlueLab v2.1 through to at least BlueLab v2.6. See subsequent BlueLab or 

firmware release notes for details of future compatibility. 

Note: 

RFCOMM firmware does not expose the Host Controller Interface (HCI). Therefore it is not suitable for use 

with third party stacks. 

Page 3 of 26 


2 Firmware Identification 

This firmware is named RFCOMM1.1v16.4.4. 

“RFCOMM” indicates that this is an RFCOMM variant of firmware. 

“1.1” indicates that this release supports v1.1 of the Bluetooth Specification [BT]. 




Firmware Identification 

“v16.4.4” indicates that this firmware is based upon the HCI Stack1.1v16.4 firmware build and that this is the 

fourth (.4) build based upon this firmware. 

Two variants for this firmware are provided. The first variant fits into a 4Mbit flash and supports BlueCore Serial 

Protocol (BCSP) and the Bluetooth Universal Asynchronous Receiver Transmitter (UART) protocol as described 

in section H:4 of the Bluetooth Specification [BT], but it has a reduced (24KWords) space for user applications. 

The other variant will only fit into an 8Mbit flash, but it supports all protocols including Universal Serial Bus (USB) 

as well as Device Firmware Upgrade (DFU). Each variant is available in versions that support both 56 and 128-bit 

encryption. 

Description: Build ID Identifier String 

8Mbit, 56-bit encryption, USB, BCSP, H4, DFU, 

32KWords application space 

8Mbit, 128-bit encryption, USB, BCSP, H4, 

DFU, 32KWords application space 

4Mbit, 56-bit encryption, BCSP, H4, 24KWords 

application space 

4Mbit, 128-bit encryption, BCSP, H4, 

24KWords application space 

659 2xRfc1v1Rfc16p4p4_56 

660 2xRfc1v1Rfc16p4p4_128 (1) 

657 2xRfc1v1Rfc16p4p4_56 

658 2xRfc1v1Rfc16p4p4_128 (1) 

Table 2.1: Available Firmware Variants 


(1) For 128-bit encryption, contact sales@csr.com. 

Build IDs and identifier strings can be checked using the PSTool application available from CSR. 

Page 4 of 26 


3 Target Hardware 




Target Hardware 

This release only runs on CSR’s Bluetooth chip BlueCore2-External. The software makes use of a flash memory 

device to hold the program, constant data and non-volatile data. This version of the firmware has been tested on 

flash devices SST SST39VF400A (used on Casira), AMD AM29LV400BB and Sharp LH28F800BJHB-43. 

Previous builds have also been tested on Fujitsu MBM29LV400BC, SST SST39VF800 and Intel 

TE28F800B3B90. 

Page 5 of 26 


4 Qualification Information 




Qualification Information 

This firmware has been qualified to v1.1 of the Bluetooth Specification [BT] for BB (baseband), LM (Link 

Manager), L2CAP, RFCOMM, SPP (Serial Port Profile), SDP and GAP (Generic Access Profile). See the 

standard PICS (Protocol Implementation Confirmation Statement) documents on CSR’s website for further 

information. 

Page 6 of 26 


5 Functional Restrictions 

5.1 4Mbit Variant 

This is an RFCOMM release and does not support HCI. 

This release only supports BCSP and H4 transports; it does not support USB 

This release does not support DFU. 




Functional Restrictions 

This release has been only lightly tested with multiple concurrent RFCOMM or L2CAP connections (piconets). 

RFCOMM bandwidth is limited to approximately 380kbit/s. 

The following built-in self-test (BIST) modes are not supported in the 4Mbit variant. (Names are as used in CSR’s 

BlueTest utility.) 

DEEP_SLEEP 

SETTLE 

IF_RESP 

VCOTRIM 

RF_IQ_MATCH 

IF_IQ_MATCH 

BUILD_LUT 

READ_LUT 

LOOP_BACK 

RX_LOOP_BACK 

BER_LOOP_BACK 

CFG_UAP_LAP 

CFG_ACC_ERRS 

CFG_IQ_TRIM 

CFG_TX_TRIM 

CFG_LO_LVL 

CFG_TX_COMP 

CFG_SETTLE 

SETTLE_RPT 

5.2 8Mbit Variant 

This is an RFCOMM release and does not support HCI. 

This release has been only lightly tested with multiple concurrent RFCOMM or L2CAP connections (piconets). 

RFCOMM bandwidth is limited to approximately 380kbit/s. 

Page 7 of 26 


6 Known Issues 




Known Issues 

Table 6.1 is a digest of issues relevant to RFCOMM firmware users. Refer to [HCIRELEASE] for a list of issues 

that affect the radio performance. 

ID Severity Description 

1-128 Low 

1-243 

1-253 

Low 

H16.157 Medium 

A total of 65531 outgoing RFCOMM connections can be made before the chip must 

be reset. This issue is classified as of low severity since it is unlikely that many 

implementations will require this many sequential connections without undergoing 

an intervening hardware reset. 

If a large amount of RFCOMM data is sent to the chip after an RFCOMM connection 

has been closed, unpredictable behaviour may be seen. This issue is classified as 

of low severity because it can only be provoked by illegal behaviour on the part of 

the host. 

When using Sniff, power consumption is higher than is necessary. This is due to 

processor activity being triggered at the end of a Sniff interval. The extra power 

consumption may make this build unsuitable for embedded products such as 

headsets or mice where battery life is important. 

Table 6.1: Known Issues 

Page 8 of 26 


c02-srn-005Pa 



Changes Relative to RFCOMM1.1v15.2.1 Release 

7 Changes Relative to RFCOMM1.1v15.2.1 Release 

A number of baseband-level changes and fixes have been made. Refer to [HCIRELEASE] for details. 

This firmware incorporates VM revision v5.8. This adds traps for the following: 

Monitoring and defragmenting the Persistent Store. (PsFreeCount, PsFlood) 

Improved CODEC control (CodecSetOutputGain, CodecSetInputGain, CodecInputGainRange, 

CodecOutputGainRange) 

Read-only file system (StreamFileSource, FileFind, FileType) 

Firmware I 2 C access (I2cTransfer) 

Power-control (VmTransmitPowerSetDefault, VmTransmitPowerSetMaximum, 

VmTransmitPowerGetDefault, VmTransmitPowerGetMaximum) 

Ability to use memory as a stream source (StreamSourceRegion) 

Access to auxiliary DAC (PioSetAuxDac) 

/dev/null equivalent for streams (StreamConnectDispose) 

Support for DFU (VmRebootForDfu) 

Direct control of RTS line (PioSetRts) 

Ability to switch stream modes (StreamSourceFromSink, StreamSinkFromSource) 

DFU and USB support has been added to the 8Mbit variant. 

Page 9 of 26 


c02-srn-005Pa 



Issues Resolved Since RFCOMM1.1v15.2.1 Release 

8 Issues Resolved Since RFCOMM1.1v15.2.1 Release 

ID Description 

1-205 

L2CAP connectionless data did not work. Only profiles such as TCS-BIN are likely to use 

connectionless data. 

1-241 RFCOMM does not send parameter negotiation response with the same priority as request. 

1-256 

1-296 

1-273 

1-274 

B-43 

The clock offset field in returned HCI_ReadClockOffsetComplete was passed to the DM clock 

offset cache, even if the status of the read was not SUCCESS. This sometimes resulted in an 

invalid clock-offset being cached if the command was issued as the connection was being torn 

down. 

When periodically sending data (approximately every 50ms) test_cable occasionally stops 

transferring data over the air. After about 15 seconds it resumed, but data sent over the UART in 

those 15 seconds was lost. 

RFCOMM test TC/RFC/BV-19-C attempts to send an RPN with one value byte. This is to be 

interpretted as a query and the IUT should respond with its own values. It is not stated in 

RFCOMM or TS07.10 what the value of the parameter mask should be in this case, but 

Bluestack set all bits to 0. The behaviour has been changed so that 0x3f7f is returned instead. 

RFCOMM test TP/RFC/BV-12-C checks that the IUT stops sending data when an FCOFF 

request is sent to the IUT. The on-chip stream library ignored old-style flow-control and thus 

failed this test. 

It was not possible to simultaneously run L2CAP and RFCOMM clients; this would manifest itself 

as a failure to respond to RFCOMM requests after an L2CAP_REGISTER_REQ. 

Page 10 of 26 


9 Piconet Support 




Piconet Support 

The default Persistent Store settings are optimised for point-to-point applications, such as headset, 

audio-gateway, dial-up networking (DUN), cable-replacement, etc. These settings may need to be modified to 

support piconets containing two or more slaves using RFCOMM. CSR has successfully tested data transfer over 

RFCOMM between a master and three slaves. Contact CSR for technical assistance in modifying Persistent 

Store settings to support this scenario. 

Page 11 of 26 


10 Testing 

The firmware has been tested with particular stress laid on the following features: 

Ability to run applications such as a headset from within the VM 

Ability to enter and leave Deep Sleep 

Bulk and multiple data transfers using RFCOMM 

Interoperability with other stacks and hardware manufacturers when used as the basis for applications 

(e.g., the headset profile) 

Regression testing of closed defects 




Testing 

Additionally, the HCI build upon on which this firmware is based is heavily tested. See [HCIRELEASE] for details. 

Neither the USB nor DFU have been heavily tested. 

Page 12 of 26 


11 BlueLab Compatibility 




BlueLab Compatibility 

‘X’ indicates compatibility, numbers indicate partial compatibility. See the appropriate note(s) for details. 

Firmware Version 

Firmware version numbers apply to both HCI and RFCOMM firmware releases 

BlueLab ID: v10.3 v10.7 v12.x v13.x v14.x v15.x v16.2 v16.4 

BlueLab 1.4 X X 



BlueLab 1.7 X (1) X 

BlueLab 1.8 X 

BlueLab 1.9 

(a, b, c, d, e variants) 

BlueLab 2.0 X 

X 

BlueLab 2.1 X (2) X (3) X (3, 4) X X 

BlueLab 2.2 X (3) X (3, 4) X X 

BlueLab 2.3 X (3, 4) X X 

BlueLab 2.4 X (3, 4) X X 

BlueLab 2.5 X (3) X X 



Table 11.1: BlueLab Compatibility 

Notes: 

(1) Host comms are not available with this combination, nor with BlueLab before v1.7 

(2) BlueCore01 only 

(3) BlueCore2 only 

(4) The BlueFlashCmd tool supplied with BlueLab v2.4 and earlier versions may report a verify error on 

sector zero when attempting to program the flash with RFCOMM1.1v15.2.1 or later firmware. This error is 

caused by a bug in BlueFlashCmd and may be safely ignored. However, customers wishing to use 

RFCOMM1.1v15.2.1 firmware with applications produced using these versions of BlueLab may suppress this 

error by either: 

Using the BlueFlashCmd utility from BlueSuite v1.11 to manually program the merged file produced 

by the make bc02 step. 

Migrating user application and any modified libraries to BlueLab v2.5. In most cases this should 

simply mean copying the application files to the new BlueLab application directory and recompiling. 

Page 13 of 26 


12 RFCOMM Throughput Measurements 




RFCOMM Throughput Measurements 

The following graphs were generated using a PC to transfer data between two Casiras. Both Casiras were set to 

the same Baud-rate and used BCSP. The throughput, therefore, represents the minimum transmit and receive 

rates. The fc_threshold field in the RFC_INIT_REQ was set to 0 for these tests. 

The decrease in throughput at framesizes around 370 bytes is due to a feature of RFCOMM flow-control. In this 

release, the on-chip RFCOMM buffer size is approximately 750 bytes. For frame-sizes of less than 370 bytes, it is 

possible to fit two or more frames in the buffer simultaneously. The host can transfer a packet over BCSP while 

BlueCore2-External transmits a packet over the radio. At frame-sizes greater than 370 bytes, it is only possible to 

fit a single frame into the buffer and the host must wait for the frame to be transmitted over the radio before 

transferring another frame over BCSP. 

Figure 12.3 and Figure 12.4 show equivalent Baud-rate, and illustrate the rate at which an RS232 link (using one 

start, one stop, and one parity bit) would have to run in order to match the transfer rate across the air. For 

example, an RFCOMM radio link transferring 40kbits/s is transmitting as much data as a wired V.90 modem 

communicating with a PC at 56k Baud. 


The default RFCOMM framesize of 127 does not give the maximum throughput at higher Baud rates; CSR 

recommends that a higher framesize be negotiated if high throughput is required. 

Page 14 of 26 


Throughput (kbits/s) 


Figure 12.1: RFCOMM Throughput (Master to Slave) vs. Frame Size 




Page 15 of 26 


Throughput (kbits/s) 


Frame Size (bytes) 

Figure 12.2: RFCOMM Throughput (Slave to Master) vs. Frame Size 




Page 16 of 26 


Equivalent Baud Rate (kBaud) 






Figure 12.3: RFCOMM Equivalent Baud Rate (Master to Slave) vs. Frame Size 

Page 17 of 26 


Equivalent Baud Rate (kBaud) 






Figure 12.4: RFCOMM Equivalent Baud Rate (Slave to Master) vs. Frame Size 

Page 18 of 26 


Frame-Rate (Frames/s) 



Figure 12.5: RFCOMM Frame-Rate (Master to Slave) vs. Frame Size 




Page 19 of 26 


Frame-Rate (Frames/s) 



Figure 12.6: RFCOMM Frame-Rate (Slave to Master) vs. Frame Size 




Page 20 of 26 


13 Host-to-BlueCore RFCOMM Flow Control 

13.1 Background 




Host-to-BlueCore RFCOMM Flow Control 

The Bluecore2-External chip has a limited amount of RAM (random access memory) available to buffer data prior 

to transmitting it over the radio. It is important that a host does not overflow this memory when streaming data to 

a peer. Earlier releases of the firmware attempted to moderate the flow of credits in order to control the amount of 

data on-chip. This had a detrimental effect on data rates and stability, and this has led to the introduction of the 

mechanism described in this document. 


This flow control mechanism need only be implemented by hosts. VM applications that use RFCOMM do not 

need to use flow-control. 

13.2 Flow Control Layer 

Flow control may be treated as a layer between the application lower layers and the transport. 

Application 

RFC Primitives 

Flow Control Layer 

RFC Primitives + Flow Control Primitives 

Transport 

Figure 13.1: Flow Control Layer 

The flow control layer (FCL) is responsible for preventing the chip from being flooded with RFCOMM data 

requests or other primitives. In order to accomplish this, it must monitor the number of primitives issued to the 

chip and the number consumed. The number of primitives consumed is published by the chip in the form of a 

special RFC_DATA_IND primitive. 

Any RFC_DATA_IND primitive with mux_id set to 0xff and payload_length set to 0 is actually a flow 

control token (FCT) and should be interpreted and consumed by the FCL. A primitive with this form has an 

overloaded form of credits field, which should be interpreted as the number of primitives consumed by the 

chip. 

The FCL must ensure that at any time the accumulated size (in bytes) of all primitives on-chip is less than 

RFCOMM_BUFFER_SIZE. This can be managed in a number of ways: the simplest is to assume that each 

packet sent to the chip is of a size equal to that of the largest RFC_DATA_REQ that can be sent, e.g., 12 (for 

header) plus the frame size negotiated during RFCOMM parameter negotiation. 

Page 21 of 26 


Call this maximum primitive size “p”, then define a window: 

window = (RFCOMM_BUFFER_SIZE)/p 

where RFCOMM_BUFFER_SIZE = 1024 – 256 

The FCL must ensure that: 

num_prims_issued – num_prims_consumed

14 Document References 

Document ID Document Reference 

[BT] Specification of the Bluetooth System, Volume 1, Core, v1.1, 22 February 2001 

[BSUG] Bluestack User Manual; Mezoe document C6066-UM-001 v1.6 

[HCIRELEASE] 

Further Reference 


bcore-srn-013Pa, BlueCore2-External HCIStack1.1v16.4 Software Release Note, 

November 2002 

[BTSECURITY] Bluetooth Security Architecture 1.C.116/1.0 



Document References 

Page 23 of 26 


Acronyms and Definitions 





BlueCore Group term for CSR’s range of Bluetooth chips, currenctly bc01b, BC2 and variants 

BlueLab CSR’s software development kit for applications running in BlueCore’s VM 

Bluetooth A set of technologies providing audio and data transfer over short-range radio connections 

Casira CSR’s main Bluetooth evaluation hardware 

BlueCore01 CSR Bluetooth chip 

BlueCore2 CSR Bluetooth chip 

ACK ACKnowledge 

API Application Programming Interface 

BB BaseBand 

BCCMD BlueCore Command 

BCSP BlueCore Serial Protocol; proprietary CSR UART protocol 

BIST Built-In Self-Test; also referred to as “radio test” 

CFC 

Credit-based Flow Control; RFCOMM mechanism for implementing application-layer 

flow-control 

CSR Cambridge Silicon Radio 

CODEC COder DECoder 

DAC Digital-to-Analogue Converter 

DFU Device Firmware Upgrade 

DM Device Manager 

DSP Digital Signal Processor 

DUN Dial-Up Networking 

ETSI European Telecommunications Standards Institute 

FCOFF Flow Control OFF 

FCL Flow Control Layer; host-side entity responsible for implementing RFCOMM flow-control 

FCT Flow Control Token; primitive used as part of RFCOMM flow-control 

GAP Generic Access Profile 

H4 HCI UART Transport Layer; described in section H4 of BT 

HCI Host Controller Interface; interface between host and Bluetooth module 

I 2 C Inter-Integrated Circuit 

IUT Implementation Under Test 

L2CAP Logical Link Control and Adaptation Protocol; element of Bluetooth 

LC Link Controller 

LM Link Manager 

MCU MicroController Unit; microprocessor, DSP or other processor 

NOP No Operation 

PC Personal Computer 

PCM Pulse Coded Modulation; digitised audio sample stream 

PICS Protocol Implementation Confirmation Statement 

RAM Random Access Memory 

RFCOMM Serial cable emulation protocol; element of Bluetooth 

RPN Remote Port Negotiation 

RTS Request To Send 

SCO Synchronous Connection-Oriented 

Page 24 of 26 


SDK Software Development Kit 

SDP Service Discovery Protocol; element of Bluetooth 

SPP Serial Port Profile 

TCS-BIN GSM standard reference: TS07.1-, v6.3.0, ETSI 

UART Universal Asynchronous Receiver Transmitter 

USB Universal Serial Bus 





VM Virtual Machine; environment in the BlueCore firmware for running customer applications 

Page 25 of 26 


Record of Changes 

Date: Revision Reason for Change: 

12 FEB 03 a Original publication of this document (CSR reference: bc02-srn-005Pa) 


BlueCore 2-External 

RFCOMM1.1v16.4.4 

Software Release Note 


February 2003 



Record of Changes 

Bluetooth and the Bluetooth logos are trademarks owned by Bluetooth SIG Inc, USA and licensed to CSR. 

BlueCore is a trademark of CSR. 

All other product, service and company names are trademarks, registered trademarks or service marks of their 

respective owners. 

CSR’s products are not authorised for use in life-support or safety-critical applications. 

Page 26 of 26

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