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