45
Intended Learning Outcomes for This Topic
3
➌ Identify the tradeoffs in selecting components for a given hardware design
By the end of this topic, you should be able to:
➋ Enumerate the hardware components in an embedded sensor hardware platform
➍ Evaluate schematics to infer a system’s functionality
➊ Propose an embedded hardware design to address a given engineering application
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4
[1] P. Stanley-Marbell and M. Rinard. “Warp: A Hardware Platform for Efficient Multi-Modal Sensing with Adaptive Approximation”, IEEE Micro, 2020.
[2] P. Stanley-Marbell and M. Rinard. “A Hardware Platform for Efficient Multi-Modal Sensing with Adaptive Approximation”, arXiv:1804.09241, 2018.
[3] P. Stanley-Marbell, P.-A. Francese, and M. Rinard. “Encoder Logic for Reducing Serial I/O Power in Sensors and Sensor Hubs”, HotChips’16, 2016.
[4] P. Stanley-Marbell and M. Rinard. “Lax: Driver Interfaces for Approximate Sensor Device Accesses”, In USENIX HotOS XV, 2015.
New: 2nd Generation of Warp
: A Research Multi-Sensor Platform
Warp
45
5
Size reference:
2nd Generation of Warp Research Platform
Warp
45
6
Programmable I/O Pullups
(TI TS5A1066 CMOS switch)
Sensors
Photodiodes
(Vishay TEMD5080)
CPU
ARM Cortex-M0+
Analog
Power
Mux
(TI
TS5A3154)
Charge
Monitoring
(ADC Built
into KL03)
(Freescale KL03)
GPIO
SPI
I2C
Sensor 1
…
Sensor 21
4
4
Power Conditioning
(TI TPS61070)
Supercapacitors
(Panasonic XH-HG)
Regulator #2
(TI TPS8267x)
Programmable Regulator #1
(TI TPS82740)
Block Diagram for 1st Generation of Warp (revA)
Warp
45
Step 0: Design Goals
7
The Idea
▶︎ Sensor accuracy (vs. measurand) varies with supply voltage
▶︎ Sensor power dissipation also varies with supply voltage
▶︎ Sensor precision (vs. measurand) varies with settings / part
▶︎ Sensors for one physical phenomenon (e.g., acceleration) may be
substituted with sensors for another (e.g., angular rate)
Goals
➋ Platform that let’s us investigate the above, across a dozen or so different state-of-the-art sensors
➌ Support for dynamically varying the supply voltage of sensors
➍ Support for energy scavenging
➊ Exploit all the above in a system able to run of scavenged energy
➎ Design in a form factor small enough to use for wearable applications
A self-powered sensor platform for research
Why?
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Step 1: System Architecture
8
Programmable Regulator #2
(TI TPS82671)
7 mm
2
area
Programmable Regulator #1
(TI TPS82740)
7 mm
2
area
Programmable I/O Pullups
(TI TS5A1066 CMOS switch)
2 mm
2
area
Approximation Hardware
SensorsEnergy Scavenging
Photodiodes
(Vishay TEMD5080)
9×23 mm
2
area
Power Conditioning
(TI TPS61070)
10 mm
2
area
CPUs
CPU #1
(Freescale KL03)
16 mm
2
area
CPU #2
(Freescale KL03)
16 mm
2
area
Bluetooth LE
Radio Module
(Panasonic
PAN1326)
90 mm
2
area
Radio
Analog
Power
Mux
(TI
TS5A3154)
2 mm
2
area
Supercapacitors
(Panasonic XH-HG)
9×24 mm
2
area
Charge
Monitoring
(ADC Built
into KL03)
0 mm
2
area
Accelerometer
(Freescale MMA8451Q)
9 mm
2
area
IR Photometer
(TI TMP006B)
3 mm
2
area
Hygrometer,
Thermometer
(SiLabs Si7021)
9 mm
2
area
Barometer
(ST LPS25H)
7 mm
2
area
Accelerometer,
Gyroscope,
Magnetometer
(Bosch BMX055)
14 mm
2
area
RGB Photometer
(TAOS TCS3772)
5 mm
2
area
Barometer
(Bosch BMP180)
14 mm
2
area
Gyroscope
(ST L3GD20H)
9 mm
2
area
Magnetometer
(Freescale MAG3110)
4 mm
2
area
Accelerometer
(ADI ADXL362)
10 mm
2
area
Hygrometer
(TI HDC1000)
4 mm
2
area
45
Step 1: System Architecture
9
Programmable Regulator #2
(TI TPS82671)
7 mm
2
area
Programmable Regulator #1
(TI TPS82740)
7 mm
2
area
Programmable I/O Pullups
(TI TS5A1066 CMOS switch)
2 mm
2
area
Approximation Hardware
SensorsEnergy Scavenging
Photodiodes
(Vishay TEMD5080)
9×23 mm
2
area
Power Conditioning
(TI TPS61070)
10 mm
2
area
CPUs
CPU #1
(Freescale KL03)
16 mm
2
area
CPU #2
(Freescale KL03)
16 mm
2
area
Bluetooth LE
Radio Module
(Panasonic
PAN1326)
90 mm
2
area
Radio
Analog
Power
Mux
(TI
TS5A3154)
2 mm
2
area
Supercapacitors
(Panasonic XH-HG)
9×24 mm
2
area
Charge
Monitoring
(ADC Built
into KL03)
0 mm
2
area
Accelerometer
(Freescale MMA8451Q)
9 mm
2
area
IR Photometer
(TI TMP006B)
3 mm
2
area
Hygrometer,
Thermometer
(SiLabs Si7021)
9 mm
2
area
Barometer
(ST LPS25H)
7 mm
2
area
Accelerometer,
Gyroscope,
Magnetometer
(Bosch BMX055)
14 mm
2
area
RGB Photometer
(TAOS TCS3772)
5 mm
2
area
Barometer
(Bosch BMP180)
14 mm
2
area
Gyroscope
(ST L3GD20H)
9 mm
2
area
Magnetometer
(Freescale MAG3110)
4 mm
2
area
Accelerometer
(ADI ADXL362)
10 mm
2
area
Hygrometer
(TI HDC1000)
4 mm
2
area
(the eventual result)
45
Step 2: Before Anything Else, Check Part Availability
10
Where to go:
▶︎ Digikey (wider range, but more expensive)
▶︎ Mouser
▶︎ In the UK/Europe, also: Farnell, RS, etc.
45
Step 3: Prototype with a Breakout Board / Dev. Board
11
TI TMP006
IR Temperature
Sensor
ST L3G4200D
Gyroscope
Sensor
45
Step 4: Implement the Software on Dev. Boards
12
➊ You need to do this before you finalize the schematics
➋ You need to do this before you finalize the schematics!
➌ You need to do this before you finalize the schematics!!
45
Step 4: Implement the Software on Dev. Boards
13
You’ve had practice with this in Coursework #2 and #3
The custom platform in today’s lecture uses the same tools setup
Things to take into account
▶︎ How much memory does the μC have?
▶︎ How much memory does your code use (look at map file)
▶︎ Based on available memory, decide on size of stack and heap
Change
in
KSDK_1.1.0/demos/<xxx>/master/armgcc/frdmkl03z/CMakeLists.txt
PC + 0: addiu sp,sp,-56
PC + 4: sw s0,24(sp)
PC + 8: move s0,a0
PC + c: lui a0,0x0
PC + 10: sw s1,28(sp)
PC + 14: addiu a0,a0,0
PC + 18: li a2,16
PC + 1c: addiu v0,sp,16
PC + 20: move s1,a1
PC + 24: lui a1,0xfff4
PC + 28: sw ra,40(sp)
PC + 2c: sw s3,36(sp)
PC + 30: sw s2,32(sp)
PC + 34: swc1 $f21,48(sp)
PC + 38: swc1 $f20,52(sp)
...
PC = Interrupt Vector Table
Save registers
...
Handle interrupt
...
Restore registers
Interrupt
(e.g., network,
battery, timer,
failure, etc.)
Memory-Mapped
Registers
Main Memory
Interrupt Vector Table
(a) Example memory map.
(b) Example flow of instruction execution in the
presence of interrupts from modeled peripherals.
Heap
Stack
.text, .data, .bss
… --defsym=__stack_size__=0x300 -Xlinker --defsym=__heap_size__=0x200
45
Step 5: Schematics
14
Programmable Regulator #2
(TI TPS82671)
7 mm
2
area
Programmable Regulator #1
(TI TPS82740)
7 mm
2
area
Programmable I/O Pullups
(TI TS5A1066 CMOS switch)
2 mm
2
area
Approximation Hardware
Analog
Power
Mux
(TI
TS5A3154)
2 mm
2
area
45
Step 5: Schematics for Programmable Power Supply
15
1.8V to 2.5V
1.2V
Vout:
Vout:
TPS8267x Switching Regulator
TPS82740 Switching Regulator
45
Step 5: Schematics for Programmable Power Supply
16
1.8V to 2.5V
1.2V
TS5A3154 SPDT Switch
45
Step 5: Schematics for Sensor Subsystems
17
Sensors
Accelerometer
(Freescale MMA8451Q)
9 mm
2
area
IR Photometer
(TI TMP006B)
3 mm
2
area
Hygrometer,
Thermometer
(SiLabs Si7021)
9 mm
2
area
Barometer
(ST LPS25H)
7 mm
2
area
Accelerometer,
Gyroscope,
Magnetometer
(Bosch BMX055)
14 mm
2
area
RGB Photometer
(TAOS TCS3772)
5 mm
2
area
Barometer
(Bosch BMP180)
14 mm
2
area
Gyroscope
(ST L3GD20H)
9 mm
2
area
Magnetometer
(Freescale MAG3110)
4 mm
2
area
Accelerometer
(ADI ADXL362)
10 mm
2
area
Hygrometer
(TI HDC1000)
4 mm
2
area
11 Sensor ICs
6 Physical Phenomena
21 Individual Sensors
45
Step 5: Schematics for HDC1000 Humidity + Temperature
18
Connected over I2C
I2C Address 0x43
Note: Several pins used
for multiple purposes
45
Step 5: Schematics for BMX055 (Accelerometer 1)
19
Connected over I2C
Responds to three I2C Address 0x18, 0x68, and 0x10 (for the accelerometer, magnetometer, gyro)
45
Step 5: Schematics for MMA8451Q (Accelerometer #2)
20
Connected over I2C
I2C Address 0x1C
45
Step 5: Schematics for ADXL362 (Accelerometer #3)
21
Connected over SPI
45
Step 5: Schematics for Bluetooth LE Radio Subsystem
22
Bluetooth LE
Radio Module
(Panasonic
PAN1326)
90 mm
2
area
Radio
45
Step 5: Schematics for Bluetooth LE Radio Subsystem
23
PAN1326 Radio Module (based on TI CC2564)
45
Step 5: Schematics for KL03 Microcontroller Subsystem
24
CPUs
CPU #1
(Freescale KL03)
16 mm
2
area
CPU #2
(Freescale KL03)
16 mm
2
area
45
Step 5: Schematics for KL03 Microcontroller Subsystem
25
Freescale KL03 ARM Cortex-M0+ microcontroller
45
Step 6: Consider Manufacturing Options (Before Layout!)
26
➊ You need to do this before you do the board layout
Board manufacturer will provide you with the design rules
▶︎ Design rules specify minimum spacing between traces (wires), smallest drills (vias) etc.
▶︎ Ideally, get a design rule file for your CAD software to automatically check your design
➋ You need to do this before you do the board layout
➌ You need to do this before you do the board layout
45
Step 7: Layout
27
Before you route your signals, you will need to decide
▶︎ How many layers
▶︎ What signals go on what layers
Layer 1: Signal
Layer 2: Ground (plane layer)
Layer 3: Signal
Layer 4: Signal
Layer 5: Sensor Supply (plane layer)
Layer 6: Ground (plane layer)
Layer 7: Signal
Layer 8: Vbatt (plane layer)
Layer 9: Ground (plane layer)
Layer 10: Signal
45
Brief Example: Starting a New Design in Eagle
28
➊ New project: Simple system comprising KL03 MCU and BME680 gas sensor
This brief example was only intended to reify the steps from previous slides
▶︎ Not intended to be a tutorial; you can find many tutorials for Eagle online
▶︎ More links and resources at the end of the lecture
➋ New schematic: Connect BME680 to KL03 over I2C
➌ New layout from schematic: Placement of components and routing of traces
What we will do in the brief demo:
45
29
Next, Printed Circuit Board Manufacture
45
Bare Board (after sending Gerber files for PCB fabrication)
31
45
Option A: Send Bare Board to a Board Assembly Facility
33
45
Parts Kit (to send for PCB assembly)
34
Put it all in a box with parts list (“kit”)
+
45
Option B: Assemble Bare Board Yourself
35
45
36
Next, Printed Circuit Board Assembly
45
The Finished Product (fully-populated PCB)
38
3.6 cm
3.2 cm
Bottom ViewTop View
45
Further Reading
41
Eagle CAD tutorial:
https://knowledge.autodesk.com/support/eagle?sort=score
A good collection of resources on Eagle from Autodesk (the makers of Eagle)
▶︎ See the supplementary brief demo from the previous slide
(This course is not about PCB design. You can find many real Eagle PCB tutorials online)
Best next step:
▶︎ Like learning to swim, you can’t learn all you need from a textbook
▶︎ Create your own hardware design and get a printed circuit board manufactured
Test your understanding:
▶︎ Complete these online self-assessments on https://f-of-e.org/
https://f-of-e.org/chapter-11/#exercises
