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DAISY-7 - GPS/MEMS module

9 Degrees of Freedom module which integrated MEMS Accelerometer, Gyroscope, Compass, Barometer and GPS receiver in just 4x4cm.

Features

GPS

  • Chip Skytraq Venus638LPx
  • Up to 10 reads per second
  • 65 channels
  • Tests 8 million time-frequency hypothesis per sec
  • Open sky cold start 29 second
  • Signal detection better than -161dBm
  • Accuracy 2.5m CEP
  • ~28mA in tracking and navigation mode
  • Multipath detection and suppression
  • Digital output interface type: Serial 3V3 level
  • Datasheet in PDF format

Linear accelerometer

  • Chip ST LIS331DLH
  • 3-axes linear digital accelerometer
  • Ultra low-power mode consumption down to 10µA
  • ±2g/±4g/±8g dynamically selectable full-scale
  • 16 bit data output
  • Generators for free-fall and motion detection
  • Sleep to wake-up function
  • 6D orientation detection
  • 10000g high shock survivability
  • Digital output interface type: I2C 3V3 level
  • Datasheet in PDF format

Gyroscope

  • Chip ST L3G4200D
  • Ultra-stable three-axis
  • Three selectable full scales (250/500/2000 dps)
  • 16 bit-rate value data output
  • 8-bit temperature data output
  • Integrated low- and high-pass filters with userselectable bandwidth
  • Ultra-stable over temperature and time
  • Embedded power-down and sleep mode
  • Embedded temperature sensor
  • Embedded FIFO
  • High shock survivability
  • Digital output interface type: I2C 3V3 level
  • Datasheet in PDF format

Compass

  • Chip Honeywell HMC5883L
  • 3-Axis Magnetoresistive Sensors and ASIC in a 3.0x3.0x0.9mm LCC Surface Mount Package
  • 12-Bit ADC Coupled with Low Noise
  • AMR Sensors Achieves 5 milli-gauss
  • Resolution in ±8 Gauss Fields
  • Enables 1° to 2° Degree Compass Heading Accuracy
  • Low Power Consumption (100µA)
  • Wide Magnetic Field Range (±8Oe)
  • Sensors Can Be Used in Strong Magnetic Field Environments with a 1° to 2° Degree Compass Heading Accuracy
  • Fast 160 Hz Maximum Output Rate
  • Digital output interface type: I2C 3V3 level
  • Datasheet in PDF format

Barometer

  • Chip Bosch BMP085
  • Pressure range: 300 ... 1100hPa (+9000m ... -500m above sea level)
  • Low power: 5µA at 1 sample/sec. in standard mode
  • Low noise:
    • 0.06hPa (0.5m) in ultra low power mode
    • 0.03hPa (0.25m) ultra high resolution mode
    • down to 0.1m (rms noise) possible
  • Digital output interface type: I2C 3V3 level
  • Datasheet in PDF format

Pinout on Daisy connector J2

Pin # Signal Direction Description
1 3V3 Power supply 3.3 Volt
2 TXD I Cpu TXD serial line wired to GPS RX line
3 RXD O Cpu RXD serial line wired to GPS TX line
4 NC Not connected
5 NC Not connected
6 NC Not connected
7 SDA I/O I2C Bus DATA
8 SCL I I2C Bus CLOCK
9 NC Not connected
10 GND Power supply GND

The I2C bus is wired to the Compass, Accelerometer, Gyroscope and Barometer chips.

Fore more details please refere to the schematic.

Wirings

These are the usable connectors where to plug this board using the factory default Linux image:

Daisy connector Serial device I2C device
FOX Board G20 (+Daisy-1) D1 /dev/ttyS2 /dev/i2c-0
FOX Board G20 (+Daisy-1) D6 /dev/ttyS4 /dev/i2c-0
FOX Board G20 (+Daisy-1) D8 /dev/ttyS3 /dev/i2c-0
TERRA D10 /dev/ttyS4 /dev/i2c-0

Basic code examples

Following are some examples of code in Python to read the data from the chip mounted on the DAISY-7 using a FOX Board G20 or a Terra Board.

They use Daisy classes defined inside the the Acme Systems ablib.py.

Read NMEA messages from the GPS chip

This example reads the NMEA message send by the GPS chip on the /dev/ttyS4 serial port (FOX.D6 or TERRA.D10 daisy connectors) and shows them on the Linux command line.

readNMEA.py

Run it by typing:

~/playground/python/daisy7# python readNMEA.py
$GPGGA,115609.085,4157.9279,N,01204.6836,E,1,10,0.8,20.6,M,48.9,M,,0000*6D
$GPGSA,A,3,09,12,15,29,17,25,27,04,02,14,,,1.4,0.8,1.2*3E
$GPGSV,3,1,11,12,72,325,41,09,64,115,52,27,53,121,44,25,37,272,49*7D
$GPGSV,3,2,11,14,31,308,44,02,21,117,38,04,20,078,35,29,17,205,51*78
$GPGSV,3,3,11,15,16,182,39,17,06,039,33,22,00,273,*47
$GPRMC,115609.085,A,4157.9279,N,01204.6836,E,000.0,041.6,170712,,,A*66
$GPVTG,041.6,T,,M,000.0,N,000.0,K,A*0E
$GPGGA,115610.085,4157.9279,N,01204.6836,E,1,10,0.8,20.6,M,48.9,M,,0000*65
$GPGSA,A,3,09,12,15,29,17,25,27,04,02,14,,,1.4,0.8,1.2*3E
...

Get the GPS coordinates and show the current position on Google maps

This example filters the NMEA messages GGA - Global Positioning Systems Fix Data and shows the Latitute and Longitude value on the system console provideing an URL to see on Google maps the current GPS position.

googleCoordinates.py

Run it by typing:

~/playground/python/daisy7# python googleCoordinates.py 
     Latitude:  41.9654233333
    Longitude:  12.07834
          URL: https://maps.google.com/maps?q=41.965423,12.078340

     Latitude:  41.9654233333
    Longitude:  12.07834
          URL: https://maps.google.com/maps?q=41.965423,12.078340

     Latitude:  41.9654233333
    Longitude:  12.07834
          URL: https://maps.google.com/maps?q=41.965423,12.078340

Insert URL value on your browser and shown where the Daisy-7 is:

Read the Accelerometer chip

This example reads the X,Y and Z axis linear accelleration via I2C bus.

acc.py

Run the example then move the DAISY-7 board so see linear speed variations.

~/playground/python/daisy7# python acc.py
X=  1216 Y=-16528 Z= -2992
X=  1200 Y=-16272 Z= -2944
X=  1136 Y=-16288 Z= -3024
X=  1184 Y=-16272 Z= -2976
X=  1184 Y=-16304 Z= -2992
X=  1168 Y=-16352 Z= -2976

Read the Gyroscope chip

This example reads the X,Y and Z axis angular speed from the gyroscope chip via I2C bus.

gyro.py

Run the example then move the DAISY-7 board so see angular speed variations.

~/playground/python/daisy7# python gyro.py
X=   -10 Y=   -18 Z=     8
X=   -13 Y=   -17 Z=     8
X=    -2 Y=   -16 Z=     6
X=    -8 Y=   -18 Z=     7
X=    -7 Y=   -18 Z=     8
X=   -36 Y=   -18 Z=    14

Read the Compass chip

To read the Honeywell HMC5883L compass chip we have integrated in the ablib library part of the Think Bowl I2C Python Library.

Some features of this library are:

This is an example of code to use them:

compass.py

~/playground/python/daisy7# python compass.py
X=  -147 Y=  -184 Z=  -437
X=  -215 Y=  -314 Z=  -375
X=    57 Y=  -292 Z=  -420
X=   138 Y=  -222 Z=  -427
X=   315 Y=  -128 Z=  -353

Read the Barometer chip registers via I2C bus

baro.py

Hardware reference


DAISY-7 : GPS-MEMS daisy module EURO 79.00

Daisy-7 is a 9 Degrees of Freedom module (9DOF) with digital MEMS (accelerometer, gyroscope, compass, barometer) and a GPS receiver IC in just 4x4cm.

Note: the daisy flat cable to wire this board is not included. Don't forget to buy it (code FLAT-20CM)

| Product description | Daisy catalog |


GPSANT : GPS active antenna EURO 12.00

GPS active antenna with SMA male connector to use Daisy-7 add-on board.


FLAT-20CM : 20cm flat cable with sockets for Daisy wiring EURO 3.00

20 cm ribbon cable with 10 wires compatible with the Acme Daisy Cabling System.

At least one of these cables is required to connect each Daisy module.

if you need different lengths please consider making your own the cable using the IDC socket JJ-02291-10P-F and the flat cable FC-3754-1M.

Third party examples




Acme Systems srl
Via Aldo Moro 53 - 00055 Ladispoli (RM) - Italy
P.IVA/C.F. 08114831004
Tel +39.06.99.12.187 - Fax +39.06.622.765.31
http://www.acmesystems.it
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