Published on January 7, 2008
Team: Wireless Nothing: Team: Wireless Nothing Preliminary Design Review What is this Device?: Two-way wireless communication between to separate motorcycles. One-way wireless CD quality audio streaming from a portable device’s audio jack. Adjustable volume, microphone gain, and channel selection. Restricted access to broadcasted audio. Modular implementation of a wireless communication and audio listening device What is this Device? High Level Concept: High Level Concept Short range RF Short range RF Long Range RF Functional Block Diagram - Headset: DAC Codec ADC Codec Microcontroller Microphone Headphones Transceiver Functional Block Diagram - Headset I2C I2S I2S I2C Bus Transceiver: ADC/DAC – OR – Transceiver Transceiver Single Chip Wireless Transceiver (nRF24Z1) 2.4 GHz operating frequency Low cost Low power High-fidelity sound (16-bit) Channel selection Integrated control channel 1Mbit/s – 4Mbit/s Data Rate I2S or S/PDIF Audio Input (16bit) SPI or I2C Integrated Frequency Hopping Scheme ——I2S—— ——I2C—— Microcontroller Receiving Transceiver Transceiver Antenna Considerations: Size ~ 23cm x 1.5mm 2.4 GHz Printed Monopole Size ~ 12mm x 20mm 2.4 GHz Printed Whip Monopole 2.4 GHz Chip Antennas Size ~ Tiny < 1cm2 Reduced gain from reduced size Antenna Considerations Functional Block Diagram – Headset, DAC/ADC: DAC Codec ADC Codec Microcontroller Microphone Headphones Transceiver Functional Block Diagram – Headset, DAC/ADC I2C I2S I2S I2C Bus DAC/ADC: Microphone Microcontroller Headphones MP3 Player DAC / ADC Single Chip DAC/ADC I2S Codec Convert between analog and I2S Low power low cost High quality 16 bit sound DAC and ADC in single chip for simplicity Integrated gain control, volume control and speaker drivers if possible I2S communication to Transceiver I2C control from Microcontroller ——I2S—— Transceiver ——I2C—— ——Analog—— DAC/ADC Functional Block Diagram - uC: DAC Codec ADC Codec Microcontroller Microphone Headphones Transceiver Functional Block Diagram - uC I2C I2S I2S I2C Bus Microcontroller: Transceiver(s) Microcontroller Primary Functions Timing Control power consumption User feedback (tones, battery level) Process user input (buttons) Microcontroller (MSP430F156) Features 24kB Flash, 1024B RAM Very-low power 330uA active 1.1uA standby mode 12bit DAC I2C and SPI interfaces in hardware 48 IO pins Overkill, but we will never have to worry about exceeding code space or having too few IO pins during dev. ——I2C—— ADC/DAC Microcontroller State Diagram – Headset: State Diagram – Headset Init Base Station Search Idle Rx Tx Always Packet Tx Base Station Found Wait Wait Packet Decoded Packet Received Wake-On-Voice High Level Concept: High Level Concept Short range RF Short range RF Long Range RF Functional Block Diagram – Base Station: Functional Block Diagram – Base Station Microcontroller Base Station to Other motorcyclist Transceiver I2C I2C/I2S Bus Base Station to Audio Device Transceiver Base Station to Helmet Transceiver Serves as a booster for the helmet’s voice communications Receives voice from helmet and retransmits with larger gain Receives voice communication from other motorcyclist(s) and transmits them to the helmet Given input from helmet, switches between voice communication and music State Diagram – Base Station: State Diagram – Base Station Init Headset Search Idle Local Audio Remote Tx/Rx Voice Timeout Voice Detected Always Voice Timeout w/o Audio Headset Found Wait Wait No Audio Present Audio Device Present Audio Device Present High Level Concept: High Level Concept Short range RF Short range RF Long Range RF Functional Block Diagram - Media Device: Functional Block Diagram - Media Device ADC Codec Microcontroller Media Device Transceiver Analog I2C I2S I2C Bus Transmits streaming wireless audio from a portable device such as an mp3 player Audio is played back in the helmet Has a lower priority than voice comm Same PCB as Helmet (headphone portion left unpopulated) Simplifies Design Single circuit to debug State Diagram – Media Device: State Diagram – Media Device Init Base Station Search Idle Remote Tx Always Audio Timeout Base Station Found Wait Wait Audio Levels Present Highly Modular Design: Highly Modular Design uC Audio Codec Audio Codec uC Tx/Rx Tx/Rx Tx/Rx Tx/Rx uC Tx/Rx Audio Codec Base Station Headphone/Mic Wireless Audio Transmitter Each component is composed of several re-useable modules We only need to do low-level design and testing once Division of Labor: Division of Labor Group Responsibilities Documentation, system development, integration, system testing, and documentation Project Timeline: Project Timeline Risks and Contingencies: Risks and Contingencies Risks Unfamiliar Interfaces and Devices I2C/S, Transceiver, Codec Difficulty controlling codec/transceiver w/ uC Limited transmit range / Problems w/ interfering devices Lead time on components / Availability problems Difficulty getting RF link working (RF protocol) Compliance with FCC regulations Prevention Help from TAs, Manufacturers, Dev Boards Nordic, Texas Instruments May be short range for Expo Ordering samples far ahead of time Use Nordic dev board Will ignore them Questions ?: Questions ?