Post on 19-Feb-2016
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BICYCLE INFORMATION TRACKING SYSTEM:HARDWARE REVIEW
Alex Wanamaker
BITS HARDWARE REVIEW
BITS HARDWARE REVIEW
BITS HARDWARE REVIEW:Blinker Circuit
2 astable 555 timer circuits 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
BITS HARDWARE REVIEW:LPC2378 (U1)
NXP LPC2378 ARM7 Microcontroller 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
BITS HARDWARE REVIEW:USB Circuits
ETVS001 USB Port Protection (U2) 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 USB mini B SMD
connector (J4)
BITS HARDWARE REVIEW:Battery Circuit
Nickel-Metal Hydride High Capacity Battery Pack (B1) 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
LMZ14203 Switching Power Module (U4) Takes 8 – 42V max, outputs +3.3V or 5V based on selection
5-Pin USB mini B connector (J3) Provides +5V to U1 to power the whole system
BITS HARDWARE REVIEW:Touch Screen Controller (U5)
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
BITS HARDWARE REVIEW:ELT240320TP Touchscreen (LCD1)
2.8”, 240x320 RGB resolution
TFT touchscreen interface
Includes backlight control
BITS HARDWARE REVIEW:Micro-SD and Hall Effect Device
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 US1881 Hall Effect Device
(U8) Outputs 1 or 0 based on
magnetic field Used to calculate distance and
speed
BITS HARDWARE REVIEW:GPIO
GPIO ports: P4 (J7)
Interfaces with turn signal switches to display on-screen indicator
IO9 and IO11 detect switch voltage for left and right switches, respectively
IO10 and 12 output voltage to turn signal
P3 (J8) Powers U8, counts
pulses from U8 on IO1 for calculations
BITS HARDWARE REVIEW:Connections
12-pin Molex 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