Microchip Technology Parrot User Manual

Parrot Hardware

Parrot (Voice Recorder) with ATtiny817 Hardware User's

Guide

Introduction

This user guide describes an audio demo board based on the ATtiny817, a high-performance tinyAVR® 8bit microcontroller.

The Parrot field engagement board can be used as a voice recorder to record, play back, browse, and erase voice data. This application helps the user to quickly evaluate the ADC and DAC features of the microcontroller.

The firmware and accompanying application note ( AVR42777) is available on Atmel START http://

start.atmel.com/.

Features

• Voice Record and Playback

• Electret Microphone

• Volume Control

• 8Mb SPI Data Flash

• Single-Wire Programming via UPDI

User Guide

DS40001916A-page 1

Parrot Hardware

Introduction......................................................................................................................1

Features.......................................................................................................................... 1

1. Block Diagram........................................................................................................... 3

2. Hardware Details....................................................................................................... 4

2.1. Microphone...................................................................................................................................4

2.2. Filter for ADC................................................................................................................................4

2.3. Microcontroller..............................................................................................................................5

2.3.1. ADC............................................................................................................................... 6

2.3.2. DAC............................................................................................................................... 6

2.4. Filter for DAC................................................................................................................................7

2.5. Power Amplifier............................................................................................................................ 8

2.6. User Interfaces............................................................................................................................. 9

2.6.1. Buttons...........................................................................................................................9

2.6.2. LEDs..............................................................................................................................9

2.7. External Data Flash....................................................................................................................10

2.8. UPDI Programming Interface..................................................................................................... 10

3. Firmware Programming........................................................................................... 12

3.1. Connection................................................................................................................................. 12

3.2. Firmware.................................................................................................................................... 12

3.3. Programming..............................................................................................................................12

4. Revision History.......................................................................................................14

5. Object of Declaration............................................................................................... 15

The Microchip Web Site................................................................................................ 16

Customer Change Notification Service..........................................................................16

Customer Support......................................................................................................... 16

Microchip Devices Code Protection Feature................................................................. 16

Legal Notice...................................................................................................................17

Trademarks................................................................................................................... 17

Quality Management System Certified by DNV.............................................................18

Worldwide Sales and Service........................................................................................19

User Guide

DS40001916A-page 2

1. Block Diagram

ATtiny817

DACADC

SPI

Data Flash

AMP

Filter

Power

AMP

REC PLAY/STOP BACK FORWARD

GPIO x6

PWR REC

GPIO x2

3.3V

Volume Control

ERASE

LDO

3.3V

User

The Parrot field engagement board demonstrates the capabilities of the ATtiny817 with audio processing, using its ADC and DAC peripherals. It is possible to record, playback, erase, rewind, and fast forward by using the buttons.

Parrot Hardware

As shown in the figure above, once the “REC” (record) button is pressed, the electret microphone starts to detect an analog sound signal. The sound signal will be processed in the front-end operation amplifier and a low-pass filter will be applied to the signal. The signal will then be digitized by the ADC of the ATtiny817 microcontroller. The converted sound data is stored in the external data Flash through the SPI interface. When the button is pressed again, this recording process is stopped.

Once the “PLAY/STOP” button is pressed, the sound data stored in the data Flash is read and converted to an analog signal through the DAC on the MCU. The analog signal is then sent through a low-pass filter before it is sent to the amplifier with the set volume. This allows the user to listen to the previously recorded sound. If the button is pressed again, the play process is stopped.

The board is supplied with +5V from the Micro-USB interface with ESD protection. The applied LDO can source out 150mA @ 3.3V system power.

Figure 1-1. Parrot Board

User Guide

DS40001916A-page 3

2. Hardware Details

1uF

C19

10k

R21

VCC_P3V3

SGND

TP5

BL-MP6022P-2C-44DB

GND

Microphone

MIC1

SGND

3.3nF

C20

SGND

C17

4.7uF

100k

R18

100nF

C15

R19

SGND

39k

R20

24k

R26

VCC_P3V3

ADC_VF_HALF

18k

R40

1uF

C18

2.1 Microphone

The device is a general low-cost electret microphone. See the table below for technical parameters.

It is highly recommended to keep the microphone at least 10cm away from the sound source to avoid peak clipping or distortion of the signal.

Table 2-1. Microphone Parameters

Parameters Value

Manufacturer part number BL-MP6022P-2C-44DB

Standard operation voltage (DC) 2V

Active current <0.5mA

Sensitivity (1kHz, 0dB=1V/Pa) -44dB ±3dB

S/N ratio 58dB

Parrot Hardware

2.2 Filter for ADC

As shown in the figure below, the power for the microphone is VCC_P3V3, which is filtered by a low-pass filter to reduce noise from the power supply.

Typically, the original voice signal is quite weak, with measured amplitude around 10mV (less than 50mV). So the signal must be amplified and filtered accordingly. To make sure that the signal can be amplified without being distorted, a voltage offset is required.

Figure 2-1. Microphone Circuit

Impedance < 2.2kΩ

Frequency (Hz) 20-16,000

Directivity Omnidirectional

As shown in the figure below, the original signal is processed in a 4-order Sallen-Key Butterworth lowpass filter. The filter is designed to have a gain of 50 and a cut-off frequency of 4kHz. The amplified signal is connected to the MCU ADC input 11 (pin PB0_AIN11).

User Guide

DS40001916A-page 4

Mic. with P re-Amp lification an d filter

TP6

U5B MCP6002-I/SN

10nF

C39

5.6k

R39

1.5nF

C24

100nF

C22

GND

VCC_P3V3

15k

R42

PB0_AIN11

U5A MCP6002-I/SN

SGND

VCC_P3V3

15k

R24

2.4k

R25

SGND

GND

1uF

C23

R44

10nF

C21

2.2nF

C16

11k

R23

6.8k

R22

SGNDSGND

2.4k

R43

1uF

C40

SGND GND

18k

R40

R41

Parrot Hardware

Figure 2-2. Amplifier and Filter Circuit

The real filter response vs. frequency curve based on measured data is shown in the figure below.

Figure 2-3. Gain vs. Frequency Curve for the Low-pass Filter of the MIC

2.3 Microcontroller

The ATtiny817 is a tinyAVR 8-bit microcontroller with up to 8KB Flash, 512 bytes of SRAM, and 128 bytes of EEPROM in a 14-, 20-, and 24-pin package.

The microcontroller uses the latest technologies from Microchip Technology Inc. with a flexible and lowpower architecture including Event System and SleepWalking, accurate analog features, and advanced peripherals.

User Guide

DS40001916A-page 5

2.3.1 ADC

The Analog-to-Digital Convert (ADC) peripheral features a 10-bit successive approximation ADC with capability of a sampling rate of up to 150ksps. The ADC is connected to a 12-channel Analog Multiplexer, which allows twelve single-ended voltage inputs. The single-ended voltage inputs refer to 0V (GND).

For more detail, refer to the latest data sheet of ATtiny817 available at http://www.microchip.com/

wwwproducts/en/attiny817.

Figure 2-4. ATtiny817 ADC Block Diagram

MUXPOS

CTRLA

EVCTRL

COMMAND

Start Conversion

Parrot Hardware

WINLT

WINHT

AIN0

AIN1

AIN11

DAC

VREF

TEMP

2.3.2 DAC

The Digital-to-Analog Converter (DAC) converts a digital value to a voltage. ATtiny817 features an 8-bit Resistor String type DAC, capable of converting 350,000 samples per second (350ksps), with the internal Voltage Reference (VREF) as upper limit for conversion. The DAC has one continuous time output with high drive capabilities, which is able to drive a 5kΩ or 50pF load. The DAC has one analog output pin (DACOUT), namely the PA06, that must be configured before it can be used.

...

Internal ref

VDD

ADC

VREF

Reference sel.

Enable, Resolution

CTRLC

prescaler

CTRLB

Number of Accumulated Samples

RES

accumulate

Threshold (IRQ)

Result Ready (IRQ)

User Guide

DS40001916A-page 6

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Microchip Technology Parrot User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Introduction

Features

Table of Contents

1. Block Diagram

2. Hardware Details

Microphone

2.2 Filter for ADC

2.3 Microcontroller

DAC

ADC