The Skiidometer. Hardware Description By: Adam Lee ; Etec474; Prof. Morton; WWU

Transcription

1 The Skiidometer Hardware Description By: Adam Lee ; Etec474; Prof. Morton; WWU

2 General Description The Skiidometer is a portable meter which serves as a digital companion on the ski slopes. By using a Global Positioning System (GPS) receiver, the user can see their current position, velocity, altitude, and distance traveled. These useful measurements can be found on a convenient handheld portable device (figure 1.1) with an easy to read Liquid Crystal Display. The Skiidometer is powered by 4 AA Ni/Mh batteries and packaged in a waterproof enclosure. The principle feature is the remote big character LCD which displays current velocity mph Power ALT: 5000 FT NE TIME: 12:00 LAT: N LON: W O Figure 1.1 Assembled Skiidometer Prototype - 1 -

3 Hardware: The Skiidometer consists of seven major hardware components which are shown in Figure 1.2. Hawk Antenna LCD 1 4 x 20 Display M12+ GPS Receiver MC9S12DP256B Microcontroller Power Supply Push Button On/Off LCD 2 4 x 20 Display Figure 1.2 The Skiidometer System Hardware Circuit Description The detailed Skiidometer circuit schematic is included as the last page of this document. All the references that follow correspond to the designators from the schematic and the parts list on page 6. Power Supply Battery Pack (B1) The Skiidometer was created for outdoor use, therefore a portable power supply must be used. It is powered by four AA Ni/Mh batteries (B1) connected in series providing 6 Vdc. These four batteries will be mounted in the battery compartment of The Skiidometer housing. ON/OFF Switch (SW1) SW1 is a single pull single throw switch used to connect and disconnect power from B1 to U1 and U2, the DC-DC converters. MAX710 5-Volt Regulator (U2) The MAX710 5-Volt regulator integrates a switching step-up DC-DC converter with a linear regulator to provide a step-up/down voltage conversion. The MAX710 is good with battery operated applications where the input voltage varies above and below the regulated - 2 -

4 output voltage. This 5-volt regulator requires four capacitors (C1, C4-6), one inductor (L2) and a Schottky diode (D2) as external components. For low battery indication LBI-(pin10) has a 4V reference applied to it. LBI+(pin11) is connected to the positive B1 supply line. When LBI+ drops below 4V the LBO (pin 8) goes low and triggers an external interrupt on the IRQ pin of the microcontroller (U6). The corresponding ISR will use the /SHDN pin (pin 4) to disconnect the input from the output. MAX711 3-Volt Regulator (U1) The GPS (U4) and HAWK antenna (A1) are the only components in The Skiidometer which require a +3 Volt supply. U1 requires four capacitors (C1, C2-3, C8), one inductor (L1), Schottky diode (D1), and four resistors (R1-4) as external components. Both the MAX710 (U2) and MAX711 (U1) have the following features: Supplies 5v/500mA with Vin = 3.6V Input voltage range of +1.8V to +11V Low Noise and High Efficiency Modes Shutdown mode-disconnects input from output with 0.2uA leakage current Narrow 16-pin SO package Low battery comparator HAWK GPS Antenna (GC3LP279CA) (A1) The HAWK antenna is a general purpose GPS active antenna designed to meet the stringent environmental and performance needs of GPS applications. The 3Vdc version of the HAWK GPS Antenna is designed to operate with Motorola's M12 Oncore GPS receiver. It s small size, low-voltage operation, and low power consumption makes this one of the best for portable operations. The HAWK antenna receives the navigation solution from the ground base stations at MHz and have a typical gain of 24dB. The Noise figure is 2.2 max and the VSWR is 2.5 max. A1 has a bandwidth of 10 to 45 MHz (+/- 3 db points). A1 connects to the M12+ GPS receiver through J3, a right angle MMCX snap connector. M12+ GPS Receiver (U4) U4 is a highly integrated single board GPS receiver module. The GPS receiver tracks the NAVSTAR GPS constellation of satellites. The satellite signals received by (A1) are tracked with 12 parallel channels of L1, C/A code then downconverted to an IF frequency and digitally processed to obtain a full navigation solution of position, velocity, time and heading. The solution is output serially on pin1 of U4 to the microcontroller (U6). M12+ (U4) - S12 Interface (U6) The Motorola S12 microcontroller sends and receives data at 5V CMOS logic levels, while the M12+ GPS sends and receives data at 3V TLL logic. In order for the two components to properly communicate with each other the data must be converted. The data is transmitted serially from the M12+, TXD1 (pin 1) to the S12 RXD0 (pin 89) runs through two inverting buffers (U5A, B). The first buffer inverts the signal and converts the signal from 3V to 5V while the second buffer is to undo the invert. Transmitting data from U6 to U4 must also be converted from the 5V to 3V. To achieve this, a simple voltage divider is implemented using R6 and R

5 MC9S12 Microcontroller (U6) The MC9S12DP256 microcontroller unit (MCU) (U6) is a 16-bit device composed of standard on-chip peripherals including a 16-bit central processing unit (HCS12 CPU), 256K bytes of Flash EEPROM, 12K bytes of RAM, 4K bytes of EEPROM, two asynchronous serial communications interfaces (SCI), three serial peripheral interfaces (SPI), 29 discrete digital I/O channels (Port A, Port B, Port K and Port E), 20 discrete digital I/O lines with interrupt and wakeup capability. The Skiidometer requires use of the two SCI ports (U4, LCD 2), Port A and Port K (LCD 1). Reset Circuitry MAX314 (U3) The MAX6314 low-power CMOS microprocessor (µp) (U3) supervisory circuit is designed to monitor power supplies in µp and digital systems. The MAX6314 s RESET output is bidirectional, allowing it to be directly connected to µps with bidirectional reset inputs, such as the S12. It provides excellent circuit reliability and low cost by eliminating external components and adjustments. The MAX6314 also provides a debounced manual reset input. It is connected to the S12 via /RESET (Pin 42). BDM J1 is a 6-pin BDM header used to communicate with the S12 microcontroller. This is connected to U6 through BKGD (Pin 23) along with ECLK (PE4), MODA (PE5), MODB (PE6). The BDM connecter will provide access to maintain, upgrade or program U6. User Interface The user interface for The Skiidometer is made up of two 4x20 LCDs. One is part of the main unit while the other is remotely operated and is a big character LCD. CFAH2004A-TMI-JP (LCD1) LCD1 is a 4x20 liquid crystal display from Crystalfontz. This display is used to show the user s position, altitude, heading, and time/date. It operates with the standard HD driver configuration. It is connected in parallel to U6 s via PortA and PortK 0-2. R18 is a 10k potentiometer used to adjust the contrast of the display. A NPN transistor (Q1) will be connected with R10 and 11 to Pin 15 and 16 of LCD1 to operate the LED backlight. The backlight will be operated through PH3 using software to turn it on and off. BBP-420 (LCD2) The BBP-420 is an LCD module with attached serial interface. LCD2 is a big character display which will be used exclusively as a speedometer. It is connected serially to U6 through the second SCI TXD1 (PS3). The combination of the LCD module and attached serial interface works like a simple serial-receive terminal at 9600 baud. Common control codes like carriage returns, linefeeds, tabs, backspace, etc. are supported. The display also implements instructions for cursor positioning, backlight control, large-character display, and right- aligned printing

6 Table1.1 S12 (U6) Memory Map - 5 -

7 Item Quantity Part Description Designators 1 4 Ni/Mh AA Battery Na 3 1 4xAA Battery Holder B1 5 1 SPST - Pushbutton SW1 7 4 Capacitor - 10%, 100uF C1, C3, C4, C6 9 2 Capacitor - 10%, 4.7uF C7, C Capacitor - 10%, 0.1uF C2, C5, C9-13, C Capacitor - 10%, 22pF C14, C Capacitor - 10%, 10uF C19, C Capacitor - 10%, 330pF C Capacitor - 10%, 33nF C Resistor - 161k Ohm, 1% R Resistor - 253k Ohm, 1% R Resistor - 115k Ohm, 1% R2, R Resistor - 4.7k Ohm, 1% R Resistor - 6.8k Ohm, 1% R Resistor - 15k Ohm, 1% R Resistor - 22 Ohm, 1% R Resistor - 47k Ohm, 1% R Resistor - 39k Ohm, 1% R Resistor Ohm, 1% R Resistor - 40 Ohm, 1% R Resistor - 10k Ohm Pot, 5% R Crystal - 16MHz HC49US16.000MABJ X Inductor 47 uh TK4444-ND L Inductor 22 uh TK4444-ND L Schottky Diode MBRS130T3 D1, D V DC-DC Converter MAX711 U V DC-DC Converter MAX710 U Reset - MAX6314 U Inverter 74HCT04 U GPS Receiver M12+ U GPS Antenna Hawk (GC3LP279CA) A Microcontroller Motorola MC9SDP256B U LCD 4x20 CFAH2004A-TMI-JP LCD LCD 4x20 BBP-420 LCD Coax Connector MMCX r/a J Header 2 x 6 pin BDM J PCB Interconnect Sametec - CLP L-D P Female Header 16 pin ND P1, P Male Header 16 pin J NPN Transistor - 2N6045 Q1 Table 1.2 Skiidometer Parts List - 6 -

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