RN4020 Firmware 1.33BEC Release Note
Microchip
Date: May 2, 2016
1 Overview
Firmware version 1.33BEC is released for Microchip's RN4020 Bluetooth Low Energy Module. This release adds new the following features:
- Custom Advertising broadcast packets
- GATT Service Definition Enhancement for both public and private services
- Private (random) MAC address for Advertisements
1.1 Resolved Issues
Release 1.33BEC contains the fixes from firmware release 1.23.
1.2 Known Issues
- Compatibility with previous 1.2x or earlier is not guaranteed, especially if the application relies on SS (set local services) command to create public services. In firmware 1.33BEC, the SS command only supports battery service and device information. Firmware 1.33BEC supports creating public services (16-bit UUID) using PS and PC command, in the same manner as defining private services.
- MLDPv2 was introduced in firmware 1.20. MLDPv2 uses unacknowledged GATT writes and notifications to improve data transfer rate across the Bluetooth connection. Therefore, any data transfer over MLDPv2 may have lost bytes if the data is not received by other end. It is highly recommended to implement packet retransmission mechanism for critical data transfers, or use MLDPv1.
- When using server write commands (SHW, SUW) over UART to update GATT characteristics, providing a data payload larger than the defined length may corrupt data. To avoid data corruption, the MCU issuing the write server commands MUST ensure the payload does not exceed the defined GATT characteristic size.
1.3 New Features
GATT Service Enhancements
In firmware 1.33BEC, the SS command has been modified to support two public services: battery service and device information. The PS and PC commands are used to support 16-bit UUIDs, allowing more flexibility to define any public or private service.
User Defined Advertising Packets
The SS command has been modified to support only battery service and device information. The PS and PC commands now support 16-bit UUIDs, allowing more flexibility to define any public or private service.
Bluetooth Address Functions
Several new commands are added to manage the Bluetooth address of the device. The address can be set to specified MAC or random (private) resolvable address.
1.4 Ordering Information
- At the time of this publication, firmware 1.33BEC is available as a DFU firmware update for existing RN4020 customers. Customers who need to order RN4020 modules with the 1.33BEC firmware should contact their Microchip representative.
1.5 Firmware Upgrade
RN4020 devices, such as modules and PICTails, can be updated to firmware 1.33BEC using the DFU Update Utility which can be downloaded from the www.microchip.com\RN4020 product page. To perform a firmware update on an RN4020 module or PICTail, execute the utility on a Windows PC with a COM port connected to the RN4020 UART interface. Hardware flow control (CTS/RTS) is required to perform a DFU update. Follow the instructions in the DFU Update Utility.
2 New Commands in 1.33BEC
2.1 Connectable Advertising Payload
NA, <HEX>
This command is used to customize connectable advertisement payload. By default, a connectable advertisement started by command “A” or auto-advertisement feature has following Advertisement Data (AD) structure format:
Flags | Service UUID List 16-bit | Service UUID List 128-bit | Local Name Complete
Due to the limited size of advertisement payload, the following conditions apply:
- When private service or MLDP is enabled, AD structure Service UUID List 16-bit is omitted
- When private service and MLDP are both enabled, only the private service UUID is in the Service UUID List 128-bit.
- In the AD structure Service UUID List 16-bit, common services such as Device Info and Battery services are not listed
- AD structure Local Name Complete is added to advertisement payload only if there is enough space. Therefore, if AD structure Service UUID List 128-bit is included, device name less or equal to 6 bytes could be included in advertisement payload.
Command “NA” provides the capability to modify the default advertisement payload by adding an AD structure one at a time. The input parameter of command “NA” is the raw AD structure format without AD length. See table 1 for AD types. For details specifications of AD structure, please refer to Core Spec Vol3, Part C, Section 11 and Core Spec Supplement v4, Part A.
Command “NA” appends additional AD to the advertisement payload, not replacing previous one. To clear the advertisement payload, use command “NZ”.
The flags field is added by RN4020 module automatically.
For example, to add local device name and TX power level, use following commands:
Y// Stop advertisingNZ// clear AD payload set by previous NA & NBNA,0944617665// AD Type 0x09 Local Name Complete // local name complete, and 44617665 are ASCII // code "Dave", the name of deviceNA,0A04// add AD Tx power level, where 0x0A is AD type // Tx power level and 04 indicates output power is // 4dBm.A// start connectable advertisement with custom payload
2.2 Non-Connectable Advertisement Payload
NB,<HEX>
This command is used to customize non-connectable advertisement payload. The use of command “NB” is the similar to that of command “NA”. The difference is that command "NB" customizes non-connectable advertisement, while command “NA” customizes connectable advertisement. “NB” can be used define customer beacons
The following example defines several types of advertising packets:
// Custom ADV packet, MSD ad type (xFF), Microchip vendor ID (0x00CD) // two byte payload (0xDA1E)NB,FFCD00DA1E// AltBeacon Packet (https://github.com/AltBeacon/spec) // AD Type: (xFF) MSD, see table 1 for AD types // MFG ID: (x00CD) Microchip MFG ID assigned by BT SIG is used in this // in this example. It must be encoded little endian in payload. // Becon Code: (xBEAC) fixed value // Beacon ID:16 byte UUID: 5b60c10e62f311e59d70feff819cdc9f // 2 byte user defined: 0xdale used in this example // RefRSSI: Signed byte 0 to -127: 0xc9, (-55 dB) used in this example // Mfg Rsvd: 1 byte reserved for user defined, 0x88 used in this exampleNB,FFCD00BEAC560C10E62F311E59D70FEFF819CDC9FDA1EC988
2.3 Clear Advertisement Payload
NZ
This command is used to clear custom advertisement payload set by previous NA and NB commands. The default connectable advertisement is enabled after this command is sent.
2.4 Assign Address to Local Device
&,<MAC>
Command "&" assigns a specific address to local device. It accepts one input parameter, which is 6-byte random address. This random address could be a static or private address. For format of random address, please refer to Bluetooth Core Specification version 4.1, Vol 3, Part C, Section 10.8. If device is currently advertising, the advertising address will be immediately changed to the assigned random address. This command can be invoked directly or automated via a script. The address is not saved in NVM.
Example
&,6F1234567890 // Set random address to be 6F1234567890
2.5 Enable Resolvable Random Addresses
&R
Command "&R" generates a resolvable random address and assign it as the current random address. If device is currently advertising, the advertising address will be immediately changed to the new resolvable random address. This command can be invoked directly or automated via a script
Example
&R // Automatically generate and assign a resolvable // random address
2.6 Disable Random Addresses
&C
Command "&C" clears the random address and uses local MAC address for advertisement. If device is currently advertising, the advertising address will be immediately changed to the local MAC address.
Example
&C // Clears random address and use MAC address
3 Appendix A: AD Types
Table 1: Bluetooth AD Types for NA and NB commands
| AD Type (HEX) | Description |
|---|---|
| 01 | Flags |
| 02 | Incomplete list of 16-bit UUIDs |
| 03 | Complete list of 16-bit UUIDs |
| 04 | Incomplete list of 32-bit UUIDs |
| 05 | Complete list of 32-bit UUIDs |
| 06 | Incomplete list of 128-bit UUIDs |
| 07 | Complete list of 128-bit UUIDs |
| 08 | Shortened local name |
| 09 | Complete local name |
| 0A | TX power level |
| 0D | Class of device |
| 0E | Simple pairing hash |
| 0F | Simple pairing randomizer |
| 10 | TK value |
| 11 | Security OOB flag |
| 12 | Slave connection interval range |
| 14 | List of 16-bit service UUIDs |
| 15 | List of 128-bit service UUIDs |
| 16 | Service data |
| FF | Manufacture Specific Data |
