IOT747 IDC777 Bluetooth Module User Manual

St John’s Innovation Centre, Cowley Road
CB4 0WS, Cambridge, United Kingdom
www.iot747.com

IDC777 Bluetooth Module

IDC777
Product Information Data Sheet
Ref: IDC777-DTS-V002
Latest Update: April 7, 2023

Device description

• Bluetooth 5.4 Audio and Data Module
• UART/GPIO Command
• 11.8mmx22.2mm form factor
• LE and Classic Audio and Data
• Connect to Apps (iOS/Android/etc.)
• Qualcomm Snapdragon Sound (inc. aptX-Loss-less)

Applications

• High-End Audio Visual-Products
• Industrial Data/Audio Applications
• Automotive/Aerospace Applications
• Teleconference Equipment
• POS/Retail Sports/Leisure Equipment

Features

• LE and Classic Audio and High-Speed Data Bluetooth 5.4 Module
• Music Receiver (HFP, A2DP Sink) and Transmitter (AG-HFP, A2DP Source)
• LE Unicast and Auracast
• Profiles: HFP, HSP, AG-HFP, A2DP Sink, A2DP Source, AVRCP, SPP, BLE
• Analog and Digital Audio connection (I2S, PCM, SPDIF)
• Snapdragon Sound (aptX, aptX HD, aptX Lossless), AAC, Wide Band Speech
• Simple UART or GPIO interface for control
• Integrated Antenna, Small form factor (11.8mm x 22.2mm x 3.2mm)
• Bluetooth, FCC(US), RED(Europe), MIC(Japan), KCC(Korea) and SRRC(China) certified

Summary
IDC777-1 is ideal for developers who want to quickly and cost effectively integrate high performance Audio and Data Bluetooth functionality into their products. It is controlled through a simple UART interface that also serves for data transmissions. For the  Audio, it has Analog or Digital Outputs. The module can connect to multiple devices with multiple profiles, including the new LE Audio Unicast and Auracast (Broadcast). The power consumption is <1mAmp when connected, <1mAmp in Pairing mode and  <4mAmp when streaming music at 3.3V. It is supplied FCC, CE, IC, Korea, Japan and Bluetooth 5.4 certified. It is also supplied with sample Android and iOS Applications to help integrate the Bluetooth functionality with the product end Application. IDC777-1 features can be also customised for specific complex use cases and scenarios. Please contact info@iot747.com for customisation requests.
For additional questions or to submit technical question, go to www.iot747.com or send an email to info@iot747.com.

General Specifications

Footprint

Pinout

Notes:
PIO_X are bidirectional with weak pull down
Reset Input is with strong pull-up
USB data positive with selectable internal 1.5kΩ pull up resistor
UART are Bidirectional with weak pull up

Hardware Design Guidelines

Antenna Placement Considerations
The IDC777 requires specific layout conditions to achieve the maximum range from the onboard Antenna. The module is designed to be placed in the top left- hand corner or edge of an application board, ideally butted up to the edge of the board to allow for  maximum free space radiation from the antenna. Orientate the front of the module to face the direction that you want the maximum range for your product in the application.

The hashed area in the diagram represents the area that should be removed of metal (ground or signal tracking) on the application board. All metal should be removed in this area on all layers of the application PCB to avoid detuning the antenna. Additionally for maximum radiation, there should be no metal or metallized plastic in this area of the PCB housing or mechanical solution into which the PC is placed. A good rule of thumb is to ensure that no metallic components are placed with 25cm of the module edge in the hashed area.
Ground vias should be used on the application PCB at the edge of this clearance area to ensure good ground connectivity through all layers of the pcb. These vias should extend to the edge of the application PCB where possible.

Supply Configuration
The IDC777 is typically powered by a fixed 3V supply where the module is included in a larger portable device and charging of the battery is supported by alternative functionality outside the remit of the IDC777. This is the Fixed Voltage Supply Configuration.
Fixed Voltage Supply Configuration
For a single supply application as part of a larger portable application circuit, a regulated voltage can be used to power the IDC777 directly. There is no direct battery connection and the IDC777 is not used to charge the battery.
In this fixed voltage configuration, the pins VBAT, VBAT_SENSE and VDD_PADS are all connected to a single supply voltage rail. VCHG and VCHG_SENSE and CHG_EXT are left unconnected as per the figure below. Alternatively, we recommend connecting  them to test points if possible. Test points can help debug and testing in some cases prior to production. 

Battery Voltage Supply Configuration
Alternatively, for portable applications, the module supports an internal charger function where no extra external components are required for charging operation. In this case, the main power is supplied by a battery, typically a Li Po cell with a nominal 3.1-3.3V  supply. A 5V charger input, typically supplied by a USB source, is used to charge the battery. The IDC777 integrated Li-Ion charger is designed to support single Li-Ion cells with a wide range of cell capacities and variable VFLOAT voltages. It supports charge  rates of 2mA to 200mA with no additional external components required. This is the Battery Voltage Supply Configuration.

• Can operate at a reduced capacity down to 4.0V, VCHG minimum is 4.0V
  ** Devices operates down to 2.8V recommended software shut off is at 3.0V

VDD_PADS is generated by a fixed voltage regulator in this configuration to provide a constant voltage reference for the IO supply domain. When connected to a battery a buck/boost synchronous regulator is recommended, the circuit below provides an example.

To save the cost of an external regulator the VDD_PADS input can be connected direct to the battery input as long as all digital peripherals are tolerant of the variation of the battery voltage over its entire operating range of 2.8V to 4.24V (VFloatmax).

Module Boot Modes
If the device is ‘No Power’ state (No voltage applied to the module), a connection (voltage applied) to VBAT or VCHG will transition the module from unpowered to Active.
The device can also be in ‘Power Off’ State while there is voltage applied to VBAT. The ‘Power Off’ state is different to the No Power state because the IDC777 has voltage on VBAT. In the ‘Power Off’ state the following events boot the chip and transition it to the Active state: (1) a rising edge on SYS_CTRL held high for 20 ms or (2) a rising edge on VCHG held high for 20 ms. NOTE that the device cannot be in ‘Power Off’ when voltage is present on VCHG input. The device can transition from Active to ‘Power Off’ with a  UART command (See UART Manual) or a rising edge on SYS_CTRL.
Depending on the software configuration SYS_CTRL can be used to boot the module or wake from a dormant or sleep state. An example application below shows the SYS_CTRL driven by a push button connected to the VBAT supply, pressing the button  connects the source voltage via the resistor divider network to the SYS_CTRL input enabling the device.
Please refer to the UART Command Manual for the SYS_CTRL function once the module is booted.

To Wake-Up an external processor on Connection, PIOs can be used. With GPIO control disabled, PIOs will go High when a Bluetooth connection is established. Please refer to the UART command line manual for more details.

ESD protection
The module has no supplementary ESD protection other than that provided by the IC within the module. The Bluetooth IC ESD protection is limited to:
Human Body Model Contact Discharge per ANSI/ESDA/JEDEC JS-001
Class 2 – 2kV (all pins except CHG_EXT; CHG_EXT rated at 1kV)
Machine Model Contact Discharge per JEDEC/EIA JESD22-A115 200V (all pins)
Charged Device Model Contact Discharge per JEDEC/EIA JESD22-C101 Class II – 200V (all pins)
It is recommended to adding supplementary ESD protection to externally available interfaces in the end application.

GPIOs and UART
The module is controlled by GPIOs. This can be configured. If GPIO control is not used, these GPIOs should be left floating. The UART by default does not use RTS/CTS flow control. If the users do not expect to use it, these lines should be left floating.
Digital Pin States on RESET or after Power Up
The following table shows the Digital Pin States on RESET or after power up.

PD = Pull Down, PU = Pull Up

Audio Interfaces

IDC777 supports high quality analogue and digital audio interfaces supported by an audio application processor, high performance analogue and digital audio codecs driving Class-AB and Class-D headphone drivers.
Analogue Audio Inputs
IDC777’s analogue input pins support mono, stereo and line-in, single ended and differential input configurations. The internal High Quality 24bit ADCs support a maximum input voltage of 2.4V (at 0dB gain) and provides over 60dBs of digital and analogue  gain with a minimum 80dB of stereo separation (crosstalk). An integrated microphone bias driver with a tuneable bias voltage range from 1.5V to 2.1V delivers up to 3mA of bias current with a typical output noise of 5uVrms suitable for driving most Electret and  MEMS microphones.
The analogue audio input is configured via the software API and supports 4 standard modes Dual differential
Dual single-ended noninverted (positive inputs)
Dual single-ended inverted (negative inputs)
Single differential
Or each input can be configured individually for differential or single ended microphone or line-in input configuration. Analogue audio inputs should be AC coupled with a minimum of 2.2uF capacitor, capacitor values below this degrade the low frequency  response.
Analogue Gain
An internal pre-amplifier prior to the HQADC provides a 0-39dB of programmable gain in 3dB steps. At 0dB gain the preamplifier maximum input voltage swing is 2.4V as the gain increases the input voltage swing must reduce to avoid compressing the ADC.  The table below shows the maximum recommended analogue input voltage swing vs analogue preamplifier gain settings.

For line-in input applications a gain of 0dB is recommended
Example Application Schematics
IDC777 Analogue Audio Nets

All analogue inputs are DC coupled and must be externally ac coupled for correct operation.
Stereo Line In
A single 4-pole audio jack provides L and R audio channels:

Mono Line In
Two 2-pole audio jacks providing independent audio channels

One 2-pole audio jack providing single mono audio source, unused inputs are AC grounded

Microphone Input
Dual Microphones

Some microphones may require a higher load capacitance, in which case a maximum 2.2uF capacitor can be added across MIC_BIAS with a 10R value resistor inserted between the MIC_BIAS_A and the microphone as below:

If a single microphone is used, the unused analogue inputs should be AC coupled to ground.
MEMS Microphone

If a single microphone is used, the unused analogue inputs should be AC coupled to ground.
Analogue Audio Outputs
The IDC777’s Class-D and Class-AB headset/speaker outputs are stereo differential outputs capable of directly driving 30 mWrms into 32 Ω or 16 Ω speaker loads. Class-D operation enables reduced power consumption, ideal for headset applications, its 3-state BD modulation enables a filter-free configuration, where most of the analogue driver is powered down, supports differential headphone loads of 16 Ω/32 Ω.

To achieve optimal audio performance in direct drive applications the DACs should operate at close the maximum output voltage of 1Vrms. This can be achieved by adding source resistors between the output terminals and the speaker driver, the value of which  are double the rated speaker impedance. i.e., for 16Ω speakers use 32Ω resistors, for 32Ω speakers use 64Ω resistors.
Class-AB operation enables either headphone or speaker applications, with higher impedance loads such as differential line out or for driving an external power amplifier. For such applications requiring external power amplifiers, the output should be filtered  using a 30 kHz RC low pass filters as shown in the application schematic below:

Further noise shaping can be employed by the addition of a DC blocking capacitor between the input filter and the input resistor of the audio amplifier. This forms a high pass filter which has a 3dB cut-off frequency described by the equation below.

The recommended layout for the analogue audio outputs is to use differential routing, keeping the two channels isolated from each other and from other sensitive circuitry.
The IDC777 DK1 board uses an external audio amplifier for audio application demonstration purposes. When using an external audio amplifier, it is important to follow the manufacturers recommended circuit and layout guidelines to achieve the best possible  audio experience.
Always use a high-quality audio amplifier ideally with click and pop suppression circuits built in. These amplifiers use noise suppression and soft start techniques to filter supply noise and transients as well as minimising ground loop currents and DC offsets that  can cause degraded audio effects. Some amplifiers even employ ground sensing and suppression techniques to minimise and remove noise coupling to the audio path.
In the example amplifier circuit shown above the amplifier audio ground is connected to the main ground via a single “star” point at the audio output jack. This is suitable for connection to headphones where noise from external sources are not expected.
When connecting to external devices such as laptops in a “Line In” configuration there is a possibility that the sleeve of the audio cable can carry noise derived from the laptop. Also external devices connected through the audio cable sleeve can have different  ground potentials which causes currents to flow through the sleeve ground. In this case it is important to isolate the sleeve ground from the audio amplifier to avoid the noise coupling to the amplifier and degrading the signal source. In this case add a filter circuit or ferrite bead connecting the sleeve ground to the ground on the application board as shown below.

Some amplifiers do not support “capless” operation and require ac coupling on the input and output of the amplifier. Series capacitance can introduce clicks and pops during turn off and turn on as voltage transients occur across the capacitors causing audible  spikes on the audio output.
Choice of capacitors used in these configurations is important, avoid using ceramic capacitors as these tend to have high voltage coefficients. Use low voltage coefficients capacitors such as tantalum or electrolytic capacitors to reduce low frequency distortion effects.
In differential mode the tolerance of the source and feedback resistors which set the gain of an amplifier is important. 1% resistors give a 40dB CMRR (Common Mode Rejection Ratio) whereas 0.1% resistors give a 60dB CMRR. Use 0.1% resistors where possible.

USB supply configuration:
In many applications supply noise can significantly degrade audio performance. This is especially true in USB powered applications or where a USB source is used to charge a battery powered application. USB sources have varying noise levels and in addition to  steady state noise levels, the plugging and unplugging of USB chargers can cause large supply transients that ripple through the power supply chain to cause clicking and popping in the audio domain. It is recommended to follow good noise immunity pcb design  practices, ground isolation, short residual current return paths and the use of ferrite bead and large decoupling capacitors on USB supply connections.
An example USB supply configuration is shown below.

Digital Audio Interfaces
The IDC777 supports digital microphones as inputs, and interfaces to external audio devices via a standard I2S/PCM interface. Up to eight channels of digital microphone inputs are supported. These are grouped as four pairs, as most digital microphones  support a L/R selection pin which allows for the clocking of two microphones from the same clock, with one being sampled on the rising clock edge and the other on the falling clock edge Eight digital microphone clock frequencies can be generated. Configurable  at: 500 kHz, 571 kHz, 666 kHz, 800 kHz, 1 MHz, 1.33 MHz, 2 MHz, and 4 MHz clock frequencies.
The digital microphone, CLK and Data functions can be mapped to any PIO on the module.

I²S/PCM/SPDIF
IDC777 provides a standard I²S/PCM/SPDIF interface capable of operating at up to a 384 kHz sample rate. The I²S/PCM port is highly configurable with alternate PCM modes, and has the following options:

• SYNC edge position selectable to align with start of channel data (PCM mode), or 1 clock before start of channel
• data (I²S mode)
• Master (generate CLK and SYNC) or Slave (receive CLK and SYNC) (PCM/I²S)
• SYNC polarity (PCM)
• Long or short SYNC (PCM)
• Left or right justification (PCM/I²S)
• Sign extension / zero pad (PCM)
• Optional tri-state at end of word (PCM)
• Optional invert of clock (PCM/ I²S)
• 13/16/24-bit per sample (PCM/ I²S)
• Up to four slots per frame (PCM)

SPDIF (IEC 60958) uses biphase coding to minimize the DC content of the transmitted signal, and enables the receiver to decode clock information from the transmitted signal.
IDC777 has 2 SPDIF interfaces for input and output.These interfaces are compatible with IEC 60958-1, IEC, 60958-3, IEC 60958-4, and AES/EBU standards. Signals are input/output via PIO and typically require external line drivers (for 75 Ω cabling) or optical transceivers (‘Toslink’).
The I2S/PCM/SPDIF interface is available on dedicated pins see the Pin Out table on pages 5 and 6 for details.

Solder Reflow Profile

Zone A: Preheat: This raises the temperature at a controlled rate, typically 0.5 – 2C/s. This will preheat the component to 120°C to 150°C to distribute the heat uniformly to the PCB.
Zone B: Equilibrium1: In this zone, the flux becomes soft and uniformly spreads solder particles over the PCB board, preventing re-oxidisation. The recommended temperature for this zone is 150°C to 200°C for 60s to 120s.
Zone C: Equilibrium2: This is optional and in order to resolve the upright component issue.
Temperature is 210°C to 217°C for 20s to 30s.
Zone D: Reflow zone: The temperature should be high enough to avoid wetting but low enough to avoid component deterioration. The recommended peak temperature is 230°C to 250°C. The soldering time should be 30s to 90s when the temperature is above 217°C.
Zone E: Cooling: The cooling rate should be fast to keep the solder grains small which will give a longer lasting joint. A typical cooling rate is 4°C/s.

Ordering Information

Modules are shipped Flashed with the latest AudioAgent firmware production build.
Customers need to confirm at order with distributors that they will receive the firmware build they require. For volume orders (1k quantities), modules can be shipped flashed with custom firmware. Please inquire with info@iot747.com for more information.

Packaging

Modules are shipped in a Tape and Reel. The package and inside tape and reel dimensions are shown below:

Label Location

General Notes

IOT747 products are not authorised for use in life-support or safety-critical applications. Use in such applications is done at the sole discretion of the customer. IOT747 will not warrant the use of its devices in such applications.
While every care has been taken to ensure the accuracy of the contents of this document, IOT747 cannot accept responsibility for any errors. IOT747 reserves the right to make modifications, corrections and any other changes to its products at any time.  Customers should obtain the latest information before placing orders.
IOT747 other products, services and names used in this document may have been trademarked by their respective owners. The publication of this information does not imply that any license is granted under any patent or other rights owned by IOT747.
IOT747® is a trading name for Company Deep Limited.

IC Warning:

CAN ICES-3 (B)/NMB-3(B)
This device contains licence-exempt transmitter(s)/receiver(s) that comply with Innovation, Science and Economic Development Canada’s licence-exempt RSS(s). Operation is subject to the following two conditions: (1) This device may not cause interference. (2) This device must accept any interference, including interference that may cause undesired operation of the device.

FCC Warning:
This device complies with part 15 of the FCC Rules. Operation issubject to the following twoconditions:(1) This device may notcause harmful interference, and (2) this device must accept anyinterference received, including interference that may causeundesired  operation. Please take attention that changes or modification not expressly approved by the party responsible for compliance could void the user’s authority to operate the equipment.

Antenna used:

Notice to Host Product Manufacturer：
Any deviation(s) from the defined parameters of the antenna trace, as described by this instruction, host product manufacturer must notify us that you wish to change the antenna trace design. In this case, a Class II permissive change application is required to  be filed by us, or you (host manufacturer) can take responsibility through the change in FCC ID and IC ID (new application) procedure followed by a Class II permissive change application.

CE Statement ：
Herby,CompanyDeep Ltd declares that this IDC7 Bluetooth Module IDC777 is in compliance with the essential requirements and other relevant provisions of Directive 2014/53/EU.In accordance with Article 10(2) and Article 10(10),this product allowed to be  used in all EU member states.

Safe distance warning ：
Use the IDC7 Bluetooth Module in the environment with the temperature between -40℃ and 85℃, The device complies with RF specifications when the device used at 20cm from your body.

RF Exposure compliance statement
This Module complies with FCC radiation exposure limits set forth for an uncontrolled environment. This equipment should be installed and operated with a minimum distance of 20cm between the radiator and your body. This transmitter must not be co- located or operating in conjunction with any other antenna or transmitter.
Labelling Instruction for Host Product Integrator
Please notice that if the FCC and IC identification number is not visible when the module is installed inside another device, then the outside of the device into which the module is installed must also display a label referring to the enclosed module. For FCC, this  exterior label should follow “Contains FCC ID: 2A3WYIDC777”. In accordance with FCC KDB guidance 784748 Labeling Guidelines. For IC, this exterior label can use wording “Contains IC: 30237-IDC777”.
Installation Notice to Host Product Manufacturer
The OEM integrator is responsible for ensuring that the end-user has no manual instruction to remove or install module.The module is limited to installation in mobile application, a separate approval is required for all other operating configurations, including  portable configurations with respect to §2.1091 and difference antenna configurations.
Antenna Change Notice to Host manufacturer
If you desire to increase antenna gain and either change antenna type or use same antenna type certified, a Class II permissive change application is required to be filed by us, or you (host manufacturer) can take responsibility through the change in FCC ID&IC  ID (new application) procedure followed by a Class II permissive change application.

FCC other Parts, Part 15B Compliance Requirements for Host product manufacturer
This modular transmitter is only FCC authorized for the specific rule parts listed on our grant, host product manufacturer is responsible for compliance to any other FCC rules that apply to the host not covered by the modular transmitter grant of certification.
Host manufacturer in any case shall ensure host product which is installed and operating with the module is in compliant with Part 15B requirements.Please note that For a Class B or Class A digital device or peripheral, the instructions furnished the user manual of the end-user product shall include statement set out in §15.105 Information to the useror such similar statement and place it in a prominent location in the text of host product manual. Original texts as following:

For Class B
Note: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This  equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a  particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following  measures:

• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.

For Class A
Note: This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated  in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this  equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense.

Change Log
6/1/2021: Draft Version
9/4/2021: Minor Corrections / Typos – Added information on front page
20/7/2021: Clarified Supply configurations. Added Test Points for Fixed Supply
21/7/2021: Simplified Supply configuration – Removed detailed Power States. Deleted references to SPI as only used in IDC707.
20/1/2022: Added certification details and corrected Power Supply connection with correct Pins.

Page: 29
Copyright IOT747
IOT747, St John’s Innovation Centre, Cowley Road, Cambridge, CB4 0WS, United Kingdom
Check www.iot747.com for updates. Email: info@iot747.com
Ref: IDC777-DTS-V003

References

• Bluetooth Technology - Bluetooth modules - IOT747

Read User Manual Online (PDF format)

Download This Manual (PDF format)

Download this manual  >>