Transcript Bicycle Information Tracking System: Hardware review

Alex Wanamaker
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2 astable 555 timer
circuits
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Blinking rate: ~1.1 seconds
Q1 and Q2 used to provide
additional current for the
circuit beyond the 555
timer’s limit of 200 mA
NXP SuperFlux LEDs: 110°
viewing angle
LEDS require 70 mA min.
+3.3V supplied by GPIO P4
Interface with U1 through
6-pin Molex connector
PCB Layout of final
product
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NXP LPC2378 ARM7
Microcontroller
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32-Bit
512 kB flash
8 kB SRAM
104 GPIO ports
20 MHz crystal (X1)
Powered via +5V USB mini B
connection (J3 and J4)
Produces +3.3V for ICs,
GPIO, and external devices
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ETVS001 USB Port
Protection (U2)
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Provides protection for
each line and between the
supply voltage and
ground for up to 25 A and
500 W within 8/20 μS.
NPC1117-3.3 (U3)
18V max input, +3.3V
output
 Produces output current of
800 mA
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USB mini B SMD
connector (J4)
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Nickel-Metal Hydride High Capacity Battery Pack (B1)
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9.6V, 2 Ah rechargeable battery pack with Tamiya connector J1
2-Pin Tamiya connectors (J1 and J2)
J2 interfaces with J1 to provide power to U4
 Power can be turned on/off by the user using SWI1
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LMZ14203 Switching Power Module (U4)
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Takes 8 – 42V max, outputs +3.3V or 5V based on selection
5-Pin USB mini B connector (J3)
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Provides +5V to U1 to power the whole system
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ADS7843 controller
12-bit ADC with
synchronous serial
interface
 Typical power
dissipation: 750 μW
 Includes a shutdown
mode, with power
dissipation at ~ 0.5 μW
 Can operate on 2.7V
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2.8”, 240x320
RGB resolution
TFT touchscreen
interface
Includes
backlight control
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Micro-SD (J5)
Surface mount Micro-SD Socket
 Push in, Push out interface
 Supports up to 4 GB storage
 Interfaces with U1 to read from/write
to an SD card
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US1881 Hall Effect Device (U8)
Outputs 1 or 0 based on magnetic
field
 Used to calculate distance and speed
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GPIO ports:
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P4 (J7)
Interfaces with turn signal
switches to display onscreen indicator
 IO9 and IO11 detect
switch voltage for left and
right switches,
respectively
 IO10 and 12 output
voltage to turn signal
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P3 (J8)
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Powers U8, counts pulses
from U8 on IO1 for
calculations
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12-pin Molex
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Used to connect U1, U8,
SW1, SW2, J7, and J8
with the turn signal via
J6
Both J9 and J6 will be
detachable from the
bicycle
J10 and J11 will remain
on the frame of the
bicycle