Electronics for Physicists II (Digital)

Electronics for Physicists II (Digital)
3/23/2012
ETH Course 402-0248-00L: Electronics
for Physicists II (Digital)
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The AVR32 AT32UC3B1256
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1: Setup uC tools, introduction
2: Solder SMD AVR32 board
3: Build application around AVR32
4: Design your own PCB schematic
5: Place and route your PCB
6: Start logic design with FPGAs
AT = Atmel: Big microcontroller company
32 = 32 bit architecture
UC3 = Atmel microcontroller family
B = more powerful and expensive variant ($7
each @25 units)
• 1 = revision
• 256 = 256kB internal high speed flash memory
(32kB single cycle SRAM)
The “bronze” board
Protoboard
header
AVR32 capabilities (Ex. 3)
12MHz crystal
AVR32
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– Power and Clock Manager
– Two Multipurpose Oscillators
– Watchdog Timer, Real-Time Clock
Timer
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Interrupt Controller
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Universal Serial Bus (USB)
– Auto-vectored Low Latency Interrupt
Service with Programmable Priority
Program
button
Reset button
Power LED
3.3V IO power
USB
(5V power)
System Functions
– Device 2.0 Full Speed
(12Mbps~1MBps)
• One Three-Channel 16-bit
Timer/Counter (TC)
• One 7-Channel 20-bit Pulse
Width Modulation Controller
(PWM)
• Three Universal
Synchronous/Asynchronous
Receiver/Transmitters
(USART)
• One Master/Slave Serial
Peripheral Interfaces (SPI)
with Chip Select Signals
• One 8-channel 10-bit AnalogTo-Digital Converter, 384ks/s
AT32UC3B1256 “copper”
board schematic
ADC
PWM
1
3/23/2012
AVR32 Software Framework
Exercise 3: “Sound volume robot”
• measures sound volume and moves arm to
indicate loudness
• microphone -> preamp -> ADC -> uC -> PWM output
e.g.
GPIO, ADC,
PWM
(debugging, programming)
Electret Microphone
“RC” servos (Radio-Control Servo-Motors)
• Position controlled – Servo has internal
position measurement and controller
• Rotation angle 120 degrees
• Pulse width from 1-2ms sets desired
position
• Pulses must be sent at frequency 50200Hz
• Pulse height >2V
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Cheap (< 1$)
Electret material, no polarization voltage
is required
Low-noise JFET buffer
Metal foil is connected to source of the
JFET through metal capsule
metal capsule
metal ring
metal foil
electret foil
air gap
spacer
metal backplate
case
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Microphone + Preamp
LM324 quad JFET opamp
“low is high”
Servo power supply
2
3/23/2012
AVR32 Analog to Digital converter
• 10-bit Successive approximation
register (SAR) type
• 6 multiplexed single-ended input
channels
• Max combined sample rate
384ks/s
• External trigger
• Hardware sequencer
• Peripheral DMA
3
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