Headset Reference Design nRD24V1 User Guide v1.0 All rights reserved. Reproduction in whole or in part is prohibited without the prior written permission of the copyright holder.
User Guide Liability disclaimer Nordic Semiconductor ASA reserves the right to make changes without further notice to the product to improve reliability, function or design. Nordic Semiconductor ASA does not assume any liability arising out of the application or use of any product or circuits described herein.
Headset Reference Design v1.0 Contents 1 2 3 3.1 3.1.1 3.1.2 3.1.3 3.1.4 3.1.5 3.1.6 3.1.7 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.3 3.3.1 3.3.2 3.3.3 3.3.4 3.3.5 3.3.6 4 4.1 4.1.1 4.1.2 4.1.3 4.1.4 4.1.5 4.2 4.2.1 4.2.2 4.2.3 5 5.1 5.2 5.3 5.4 Introduction ................................................................................................. 4 System Description ..................................................................................... 5 Hardware description .......................
User Guide 1 Introduction This user guide is for the nRD24V1 headset reference design, a voice quality wireless headset for Voice over IP (VoIP) applications. The quality of the audio in this design is the same as the audio quality in telephony. This user guide describes the nRD24V1 system, HW modules and gives guidelines on how to take this reference design and build it into a headset application for a finished product.
Headset Reference Design v1.0 2 System Description The headset unit can be used to communicate with either a USB dongle or an audio dongle. Note: The audio dongle is simply a headset unit with different firmware and jumper settings. Figure 1. ”Headset unit with a USB configuration” and Figure 2. ”System diagram of headset unit with USB configuration” illustrate the headset unit with a USB configuration. Headset unit USB dongle Figure 1.
User Guide Application Voice Protocol Application ShockBurst MCU I/O I/O Audio Out Audio In PHY RF ShockBurst PHY RF Voice Protocol MCU I/O I/O DAC DAC ADC ADC Buttons LED LED Audio Out Audio In Buttons Figure 4. System diagram of headset unit with audio dongle configuration The headset unit and the audio dongle are based on the same hardware. Both use an audio codec to provide coding and decoding of the analog audio signals to 16-bit linear PCM code.
Headset Reference Design v1.0 3 Hardware description 3.1 nRD24V1 Radio module The radio module is a complete system for telephone quality wireless headset applications intended for VoIP. It can be used in a headset, or in an audio module for connection to a PC audio outlet. There are 6 GPIOs for buttons or LEDs on the radio module. The radio module is mounted on a 25 x 12 x 0.8 mm, 4-layer FR4 circuit board, with components on one side.
User Guide 3.1.2 Micro controller The micro controller is an AVR, ATmega88 and runs on a 4.096 MHz crystal. The micro controller’s main tasks are: • • • • Setting up codec and RF circuits. Converting 16 bit PCB audio samples from the codec to 8 bit a-law samples to the radio circuit. Converting 8-bit a-law samples from the radio circuit to 16-bit linear PCM. Handling the RF protocol. Additionally, five button inputs are scanned and one output is provided for driving.
Headset Reference Design v1.0 3.1.7 Specifications Operating conditions Supply voltage Current consumption Status Idle Connected Radio frequency Output power Value 1.9 - 3.6 V < 1 mA average (15 mA peak) at 2.5 V supply < 7 mA average (15 mA peak) at 2.5 V supply 2402-2478 MHz 0 dBm Table 1. Electrical Specifications PCB attributes PCB type PCB dimension (length x width x height) Description 0.8 mm 4 layer FR4 25 mm x 12 mm x 0.8 mm Table 2. Physical Specifications Revision 1.
User Guide 3.2 Application board The nRF24L01-VHR1 application board contains all peripherals necessary to build a complete audio module from the nRF24L01-VHR1 radio module. 6 7 1 8 2 9 3 4 10 5 11 1 2 3 4 5 6 Radio module Linear regulator Jumpers Audio interface Jumpers Switch 6 7 8 9 10 11 P3 external power Batteries Switches 7 and 8 ISP programming Buttons Figure 6. Application board components 3.2.
Headset Reference Design v1.0 3.2.1.1 Headset interface The loudspeaker(s) are driven differentially, and need some filtering due to the class D output amplifier of the audio codec. Figure 7. ”Loudspeaker interface” shows a typical filter network that can be used for driving a headset loudspeaker. The filter depends on the chosen loudspeaker. The microphone can be connected directly to the codec input. The codec input has a 1.1 V supply that can power a typical headset microphone.
User Guide C1 R1 C2 PC loudspeaker out AIN 2.2u 1k 2.2u R2 47 Figure 9. PC output interface 3.2.2 Jumpers The application board can be set up to interface a headset microphone and loudspeaker, or a PC audio outlet by placing the jumpers as shown in Table 3. ”Audio filter settings” below. The filter components mounted should be appropriate for most headset loudspeakers. CJ2 Connecting to Connect to headset headset microphone.
Headset Reference Design v1.0 3.2.5 Buttons There are five buttons on the application board and these are connected to the AVR micro controller on the radio module as shown in Figure 10. ”Button mapping”. SW1 AVR pin 23 SW2 AVR pin 24 SW3 AVR pin 25 SW4 AVR pin 26 SW2 AVR pin 27 Figure 10. Button mapping 3.2.6 Programming The radio module can be programmed through the 6-pin ISP connector (P1) with an AVR programming tool like the STK500 from Atmel. The programming procedure is as follows: 1. 2. 3.
User Guide 3.3 USB dongle The USB dongle establishes a wireless audio link with the radio module in a headset and is identified as an audio device in the PC operating system. The USB dongle is mounted on a 0.8 mm, 4-layer FR4 circuit board, with components on both sides of the board. 1 3 2 4 1 2 MCU MCU crystal 3 4 nRF24L01 RF crystal Figure 11. nRD24V1 USB dongle top side 2 1 3 1 2 USB MCU EE Prom 3 ISP connector Figure 12. nRD24V1 USB dongle bottom side Revision 1.
Headset Reference Design v1.0 3.3.1 USB Interface The USB interface is handled by the Sonix SN11220 USB Audio Controller. All the USB communications are handled by the SN11220. The audio samples are 16 bit linear PCM on the I2S port, where the micro controller acts as a bus master (PADFUN mode 4’1100 in the SN11220ACF data sheet). The audio frame signals are derived from the 2.048 MHz clock output from the USB controller. This synchronizes the audio frames with the USB audio frames.
User Guide 3.3.6 Specifications Operating conditions Supply voltage Current consumption Status Idle Connected Radio frequency Output power Value 4.5 - 5.5 V < 24 mA < 28 mA 2402-2478 MHz 0 dBm Table 4. Electrical Specifications PCB attributes PCB type PCB dimension (length x width x height) Description 0.8mm 4 layer FR4 42mm x 16mm x 0.8mm Table 5. Physical Specifications Revision 1.
Headset Reference Design v1.0 4 Hardware design guidelines This chapter describes important issues that might affect you when developing the headset reference design for a finished product. The USB dongle can be used as-is, but the headset must be redesigned to fit into a headset for a finished product. However, the radio module mounted on the headset can be used asis together with the audio interfaces from the application board.
User Guide 4.1.2.2 Audio interface The audio interfaces from the application board should be used when using the radio module as-is in a design. The audio interfaces are matched to the used audio codec on the radio module. Using a different codec or load on the interfaces requires redesign of the audio interfaces. 4.1.3 Crystals The crystal used as the RF crystal is a 16 MHz crystal. Any replacement of this crystal must fulfill the crystal requirements found in the nRF24L01 Product Specification.
Headset Reference Design v1.0 4.2 USB dongle 4.2.1 Antenna The USB Dongle uses a PCB quarter wave antenna. The USB Dongle is production ready, and any modifications to the antenna are only required as part of the antenna tuning process to compensate for plastic housing, and so on. If you want an antenna redesign, any 50 ohm 2.4GHz antenna can be used, from an inexpensive PCB antenna to space saving chip antennas.
User Guide 5 Appendix 5.1 Bill Of Materials (BOM) Part 10u 10n 4.7u 100p 2.2u 100n SMA 3.5mm R 470u 6PIN2ROW PH2 nRF24L01 VoIP Application Board BC847BL 470 100k 56 0 1k 47 220 22k 4.7k SW6x6 SPDT Designator C1 C3 C22 C27 C2 C4 C23 C11 C14 C16 C17 C20 C21 C25 C26 C24 CJ1 Footprint SM/0805 SM/0603 SM/0603 SM/0603 SM/0603 SM/0603 TH/SMA CJ2 CJ3 D1 L1 L5 TH/CON/KLBR4 0603_D SM/1210 P1 P3 PCB1 6PIN/2ROW PHOENIX/2.
Headset Reference Design v1.0 Part 10n 10u 1.0n 33n 4.7p 2.2n 4.7p 1.0p 15p 22p 47u Designator C1 C3 C4 C5 C6 C11 C2 C13 C22 C7 C8 C9 C10 C12 C14 C26 C15 C16 C17 C18 C23 Footprint SM/0402 SM/0805 SM/0402 SM/0402 SM/0402 SM/0402 SM/0402 SM/0402 SM/0402 SM/0402 CAPMP3528X210L 470n 2.2u G 4.7n C24 C25 D1 L1 SM/0402 SM/0603 0603_D SM/0402 8.2n L2 SM/0402 5.6n L3 SM/0402 USB-A P1 nRF24L01 VoIP USB PCB1 Dongle Board PDTC115TU Q1 22k 22 1M 100K 0 10 2.2k 3.3k 470 10k 1.
User Guide Part 100n 22p 15p 4.7p 2.2n 1.0p 10n 1u 33n 1.0n 0.8p 4.7n 8.2n 4.
Headset Reference Design v1.0 5.2 Application board schematics Revision 1.
User Guide RF module schematics 5.3 CP2 AOUTP AOUTN AIN C12 1u C11 1u R5 390k 13 14 12 10 9 5 6 11 7 VDDPA AOUTP AOUTN AIN VREG11 VREG16 VREF VSSPA VSSA U1 VDD MCLK MOSI SCK SS SDO SDI FSYNC BCLK NRESET VSSD 3 1 20 19 2 17 18 15 16 4 8 C13 100n VB R1 10 Y1 4.
Headset Reference Design v1.0 USB dongle schematics 5.4 4 3 2 1 47 22 1 2 3 4 11 10 U1 LFB LFA DR DW SK CS 37 VSS VDD VDD VDD 7 21 46 12 TAVSS 3V3 VSSA_PLLB VUSB USBDM USBDP 35 48 3V3 C25 2.2u + C23 47u R12 3.3k U4 VCC DO ORG DI SK CS 93C46 GND C13 10u 22 22 VDDOUT R8 0 C24 470n 3V3 8 6 5 3V3 C11 10n R25 1.5k R2 R3 XIUSB XOUSB VSSA_PLLA TAVDD C22 10u R21 0 VUSB R11 2.
