Renesas Electronics America Inc. © 2012 Renesas Electronics America Inc. All rights reserved. Class ID: Audio Solutions on the RX MCU Family Mitch Ferguson, Applications Engineering Manager 5L071

© 2012 Renesas Electronics America Inc. All rights reserved.2 2 Mitch Ferguson Applications Engineer Manager Provides support of design teams using ADCs in MCU system. Over 15 years of system-level design experience Over 7 years of experience as an application engineer. As a hardware engineer and engineering manager, he has been involved in design in power distribution controls, automotive and fire alarm systems with focus on analog design and EMI/EMS issues. Bachelor of science in electrical engineering from Cleveland State University

© 2012 Renesas Electronics America Inc. All rights reserved.3 Renesas Technology & Solution Portfolio

© 2012 Renesas Electronics America Inc. All rights reserved.4 Microcontroller and Microprocessor Line-up Wide Format LCDs  Industrial & Automotive, 130nm  350µA/MHz, 1µA standby 44 DMIPS, True Low Power Embedded Security, ASSP 165 DMIPS, FPU, DSC 1200 DMIPS, Performance 1200 DMIPS, Superscalar 500 DMIPS, Low Power 165 DMIPS, FPU, DSC 25 DMIPS, Low Power 10 DMIPS, Capacitive Touch  Industrial & Automotive, 150nm  190µA/MHz, 0.3µA standby  Industrial, 90nm  242µA/MHz, 0.2µA standby  Automotive & Industrial, 90nm  600µA/MHz, 1.5µA standby  Automotive & Industrial, 65nm  600µA/MHz, 1.5µA standby  Automotive, 40nm  500µA/MHz, 35µA deep standby  Industrial, 40nm  242µA/MHz, 0.2µA standby  Industrial, 90nm  1mA/MHz, 100µA standby  Industrial & Automotive, 130nm  144µA/MHz, 0.2µA standby bit 8/16-bit

© 2012 Renesas Electronics America Inc. All rights reserved.5 Microcontroller and Microprocessor Line-up Wide Format LCDs  Industrial & Automotive, 130nm  350µA/MHz, 1µA standby 44 DMIPS, True Low Power Embedded Security, ASSP 165 DMIPS, FPU, DSC 1200 DMIPS, Performance 1200 DMIPS, Superscalar 500 DMIPS, Low Power 165 DMIPS, FPU, DSC 25 DMIPS, Low Power 10 DMIPS, Capacitive Touch  Industrial & Automotive, 150nm  190µA/MHz, 0.3µA standby  Industrial, 90nm  242µA/MHz, 0.2µA standby  Automotive & Industrial, 90nm  600µA/MHz, 1.5µA standby  Automotive & Industrial, 65nm  600µA/MHz, 1.5µA standby  Automotive, 40nm  500µA/MHz, 35µA deep standby  Industrial, 40nm  242µA/MHz, 0.2µA standby  Industrial, 90nm  1mA/MHz, 100µA standby  Industrial & Automotive, 130nm  144µA/MHz, 0.2µA standby bit 8/16-bit

© 2012 Renesas Electronics America Inc. All rights reserved.6 Microcontroller and Microprocessor Line-up Wide Format LCDs  Industrial & Automotive, 130nm  350µA/MHz, 1µA standby 44 DMIPS, True Low Power Embedded Security, ASSP 165 DMIPS, FPU, DSC 1200 DMIPS, Performance 1200 DMIPS, Superscalar 500 DMIPS, Low Power 165 DMIPS, FPU, DSC 25 DMIPS, Low Power 10 DMIPS, Capacitive Touch  Industrial & Automotive, 150nm  190µA/MHz, 0.3µA standby  Industrial, 90nm  242µA/MHz, 0.2µA standby  Automotive & Industrial, 90nm  600µA/MHz, 1.5µA standby  Automotive & Industrial, 65nm  600µA/MHz, 1.5µA standby  Automotive, 40nm  500µA/MHz, 35µA deep standby  Industrial, 40nm  242µA/MHz, 0.2µA standby  Industrial, 90nm  1mA/MHz, 100µA standby  Industrial & Automotive, 130nm  144µA/MHz, 0.2µA standby bit 8/16-bit

© 2012 Renesas Electronics America Inc. All rights reserved.7 ‘Enabling The Smart Society’ Challenge: “Improving the interface to the new smart machines is one of the important concepts of the Smart Society. Audio is an effective way of improving information delivery” Solution: “This class will show you how simple it can be to add various levels of audio to your next project”

© 2012 Renesas Electronics America Inc. All rights reserved.8 Agenda Discuss audio formats and requirements Embedded applications not high quality music players Hardware Requirements DAC PWM RX Audio Demo Components Basic decoding scheme Peripheral Blocks Lab Summary

© 2012 Renesas Electronics America Inc. All rights reserved.9 Audio Experience BMW pursuing better acoustics to improve efficiency Audio used to compensate for low RPM rumble - At Mercedes-Benz...engineers record the sounds of those servo motors used to raise the windows and adjust the seats, then compare them with sounds made by a BMW and other competitor if it sounds well made, it probably is Do Your Products Sound Priceless?

© 2012 Renesas Electronics America Inc. All rights reserved.10 Audio Considerations

© 2012 Renesas Electronics America Inc. All rights reserved.11 Key Considerations What type of audio is needed Simple tones Speech Music What are characteristics and requirements File size – Internal Flash – External file storage – File system MCU and Bus Bandwidth Transducer (speaker) Amplifier/filter requirements

© 2012 Renesas Electronics America Inc. All rights reserved.12 Sample Rates and Quality 8kHz, 8 bits Telephone quality 11kHz passable voice 22kHz, 8 bits, good for a mix of mono speech and music. 44.1kHz, 16 bits Good for audio and quality speech © 2010 Renesas Electronics America Inc. All rights reserved.

© 2012 Renesas Electronics America Inc. All rights reserved.13 Telephone or Voice quality Bandwidth: 180 Hz to 3.2 kHz Low end avoids 60 Hz region. Noise pickup Size of transformers High end bandwidth issue 8 kHz sampling rate sufficient for speech intelligibility Signal to Noise: Approximately 45 dB Human voice extends from 80 Hz to 14 kHz Lab will investigate voice quality Spectrum of Audio Clip

© 2012 Renesas Electronics America Inc. All rights reserved.14 Bandwidth, Storage and Dynamic Range

© 2012 Renesas Electronics America Inc. All rights reserved.15 Dynamic Range – How many bits? 48 dB = 8 bit 60 dB = 10 bit 96 dB = 16 bit 144 dB = 24 bit

© 2012 Renesas Electronics America Inc. All rights reserved.16 Improving Dynamic Range Use signal compression techniques u-Law or A-law – 8 bit data, 8K sampling rate = 8kB/sec – Compression ratio 2:1

© 2012 Renesas Electronics America Inc. All rights reserved.17 Signal Compression - ADPCM PCM stores digitized audio - WAVE is a PCM file DPCM (Differentia) stores the difference from predicted last sample ADPCM – Adaptive – adapts step size for better compression (4:1}

© 2012 Renesas Electronics America Inc. All rights reserved.18 Audio Data Compression Comparison Audio Files

© 2012 Renesas Electronics America Inc. All rights reserved.19 Hardware requirements

© 2012 Renesas Electronics America Inc. All rights reserved.20 DAC or PWM Output Which is better? DAC is simple DAC resolution must be considered DAC settling time may limit actual audio range PWM very flexible, available on most MCUs PWM resolution may be limited depending on carrier

© 2012 Renesas Electronics America Inc. All rights reserved.21 Filter Considerations DAC output should have filter Basically same requirement as anti-aliasing filter on ADC Should filter all frequencies above sampling rate/2 May cause amplitude distortion Buffer and filter can be combined Output resistance of the DAC should be considered in the filter design Simple RC acceptable in many applications Some systems like audio the speaker or listener filters many of the unwanted higher frequencies

© 2012 Renesas Electronics America Inc. All rights reserved.22 PWM vs DAC Resolution At 10 kHz DAC settling time (3 uS) should not be a problem so all 1024 states of 10 bit DAC available Using 16 bit MTU timer 48 Mhz / 44.1 kHz = 1088 Can utilize more that 10 bits (1024) Increased resolution just adds audio dynamic range If a lower resolution audio is used interrupts can be “skipped” while still using PWM carrier © 2010 Renesas Electronics America Inc. All rights reserved.

© 2012 Renesas Electronics America Inc. All rights reserved.23 DAC Output Resistance Important specification of DAC Relatively high for many MCU DACs May require buffering in many cases Some MCUs have internal buffer If no internal buffer Rload >> Ro to prevent loading Rload>2*Resolution* Ro for <1/2 bit error Ro on RX63N is 3.6K

© 2012 Renesas Electronics America Inc. All rights reserved.24 DAC Filter Typically first order filter not enough Often use amplifier and filter

© 2012 Renesas Electronics America Inc. All rights reserved.25 Filter Considerations

© 2012 Renesas Electronics America Inc. All rights reserved.26 RX Audio Demo

© 2012 Renesas Electronics America Inc. All rights reserved.27 Renesas RX63N RDK J-Link debugger Speaker Stereo headphone jack LED Ring SD-Card Graphics LCD User push buttons POT VR1 MIC and amplifier

© 2012 Renesas Electronics America Inc. All rights reserved.28 RX Audio Demo SD-Card stack & low-level drivers FAT file system browser Supports MP3 WAV ADPCM Stereo PWM output Software volume control YRDK RX63N © 2012 Renesas Electronics America Inc. All rights reserved.

29 © 2012 Renesas Electronics America Inc. All rights reserved. RX Audio Demo - supported formats MP3 MPEG-1/Audio(ISO/IEC )LayerIII MPEG-2/Audio(ISO/IEC )LayerIII MPEG-2.5 (For Low Sampling Frequencies) ADPCM WAV (uncompressed PCM) 16-bit stereo or mono ( 1 or 2 channels) Sample rates (kHz) 44.1, , 22.05,

© 2012 Renesas Electronics America Inc. All rights reserved.30 © 2012 Renesas Electronics America Inc. All rights reserved. RX Audio Demo Decode path block diagram Raw binary Blocks File I/O MP3 decode Timers

© 2012 Renesas Electronics America Inc. All rights reserved.31 © 2012 Renesas Electronics America Inc. All rights reserved. RX Audio Demo Rendering block diagram Render PingPong DTC TPU L L R R Sample Rate Ready for next PCM data sample Reload Load next PCM sample

© 2012 Renesas Electronics America Inc. All rights reserved.32 © 2012 Renesas Electronics America Inc. All rights reserved. Timer Operation Timer count value Elapsed time TPU1.TGRB TPU0.TGRA TPU0.TGRB TPU1.TGRB clears all channels at the audio sample rate Channel A PWM Channel B PWM Sets Playback Rate

© 2012 Renesas Electronics America Inc. All rights reserved.33 © 2012 Renesas Electronics America Inc. All rights reserved. RX Audio Demo MCU peripherals used Two synchronizable "TPU" timer channels for PWM audio rendering. Data Transfer Controller (DTC) for streaming PWM timer data to the TPU timers. RSPI channel for SDCard communication 12-bit ADC to measure the potentiometer setting for audio playback volume 1 Compare Match Timer (CMT) channel for timed delays in SDCard driver code Real-time clock (RTC)--used for file time stamp

© 2012 Renesas Electronics America Inc. All rights reserved.34 Lab Time !

© 2012 Renesas Electronics America Inc. All rights reserved.35 Summary Audio formats and requirements How good is “voice quality” Hardware DAC PWM Audio Various quality levels depending on need Trade-off – File storage size – Decode bandwidth – Quality

© 2012 Renesas Electronics America Inc. All rights reserved.36 Questions? Questions?

© 2012 Renesas Electronics America Inc. All rights reserved.37 ‘Enabling The Smart Society’ Challenge: “Improving the interface to the new smart machines is one of the important concepts of the Smart Society. Audio is one of the most effective ways of improving information delivery” Solution: “This class will show you how simple it can be to add various levels of audio to your next project”

© 2012 Renesas Electronics America Inc. All rights reserved.38 Please utilize the ‘Guidebook’ application to leave feedback or Ask me for the paper feedback form for you to use… Please Provide Your Feedback…

Renesas Electronics America Inc. © 2012 Renesas Electronics America Inc. All rights reserved.