#DAISY-7 - GPS/MEMS module

<div class="text-success lead"> 
9 Degrees of Freedom module which integrated MEMS Accelerometer, Gyroscope, Compass, Barometer and GPS receiver in just 4x4cm.
</div>

<img src="./DAISY-7.jpg"/>

#Features

Operating Temperature range: <b>-30 +85 deg-C</b> 

<table class="noborder" markdown="1">
<tr>
<td valign="top">
##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](http://en.wikipedia.org/wiki/Circular_error_probable) 
* ~28mA in tracking and navigation mode 
* Multipath detection and suppression 
* Digital output interface type: **Serial 3V3 level** 
* Baudrate 115200,8,N,1 ([how to change it](/DAISY-7#gps_baudrate))
* [Datasheet in PDF format](/download/datasheets/Venus638DS_v02.pdf)

##Linear accelerometer
* Chip ST LIS331DLH
* 3-axes linear digital accelerometer
* Ultra low-power mode consumption down to 10&micro;A
* &plusmn;2g/&plusmn;4g/&plusmn;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](/download/datasheets/LIS331DLH.pdf)

## 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](http://terzo.acmesystems.it/download/datasheets/L3G4200D.pdf)
</td>
<td valign="top">
## 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 &plusmn;8 Gauss Fields
* Enables 1&deg; to 2&deg; Degree Compass Heading Accuracy
* Low Power Consumption (100&micro;A)
* Wide Magnetic Field Range (&plusmn;8Oe)
* Sensors Can Be Used in Strong Magnetic Field Environments with a 1&deg; to 2&deg; Degree Compass Heading Accuracy
* Fast 160 Hz Maximum Output Rate
* Digital output interface type: **I2C 3V3 level**
* [Datasheet in PDF format](http://terzo.acmesystems.it/download/datasheets/HMC5883L.pdf)

##Barometer

* Chip Bosch BMP085
* Pressure range: 300 ... 1100hPa (+9000m ... -500m above sea level)
* Low power: 5&micro;A 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](http://terzo.acmesystems.it/download/datasheets/BMP085.pdf)
</td>
</tr>
</table>

##Pinout on Daisy connector J2

| Pin # | Signal | Direction | Description |
|----|------|-----|-------------------------------------------------|
|  1 | 3V3  |     | Power supply 3.3 Volt  |
|  2 | TXD  | I   | Cpu <b>TXD</b> serial line wired to GPS RX line |
|  3 | RXD  | O   | Cpu <b>RXD</b> 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 <b>DATA</b>  |
|  8 | SCL  | I   | I2C Bus <b>CLOCK</b> |
|  9 | NC   |     | Not connected |
| 10 | GND  |     | Power supply GND |

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

##Hardware reference

* [Schematic in pdf format](/download/schematics/schematic_daisy7.pdf)
* [Mechanical drawing in dwg format](/download/mechanicals/mechanical_daisy7.dwg)

##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](/FOXG20) or a [Terra Board](/terra). 

They use Daisy classes defined inside the the Acme Systems [ablib.py](https://github.com/tanzilli/ablib). 

##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. 

<img src="./gps.jpg"/>

@pg='python/daisy7/readNMEA.py'

Run it by typing:

<pre class="terminal">
~/playground/python/daisy7# <b>python readNMEA.py</b>
$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
...
</pre>

##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. 

<a href="https://maps.google.com/maps?q=41.965530,12.078173">
<img src="./google_map.jpg">
</a>

@pg='python/daisy7/googleCoordinates.py'

Run it by typing:

<pre class="terminal">
~/playground/python/daisy7# <b>python googleCoordinates.py </b>
     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
</pre>                          

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

* [https://maps.google.com/maps?q=41.965530,12.078173](https://maps.google.com/maps?q=41.965530,12.078173)

##Read the Accelerometer chip

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

<img src="./accelerometer.jpg" style="width:460px"/>

@pg='python/daisy7/acc.py'

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

<pre class="terminal">
~/playground/python/daisy7# <b>python acc.py</b>
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
</pre>

##Read the Gyroscope chip

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

<img src="./gyroscope.jpg" style="width:460px"/>

@pg='python/daisy7/gyro.py'

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

<pre class="terminal">
~/playground/python/daisy7# <b>python gyro.py</b>
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
</pre>

##Read the Compass chip

<img src="./compass.jpg" style="width:460px">

To read the  Honeywell HMC5883L compass chip we have integrated 
in the [ablib library](https://github.com/tanzilli/ablib) part of the [Think Bowl I2C Python Library](http://think-bowl.com/raspberry-pi/i2c-python-library-3-axis-digital-compass-hmc5883l-with-the-raspberry-pi/). 

Some features of this library are:

* Easily set declination to get heading based on true north
* Heading can be retrieved in degrees and minutes or as a standard formated string for printing
* Instance can be treated as string to quickly test initial setup
* Axes can be read directly for other uses such as sensing magnets

This is an example of code to use them:

@pg='python/daisy7/compass.py'

<pre class="terminal">
~/playground/python/daisy7# <b>python compass.py</b>
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
</pre>

##Read the Barometer chip registers via I2C bus

<img src="./barometer.jpg" style="width:460px">

@pg='python/daisy7/baro.py'

<a name="gps_baudrate"></a>
#How to change the GPS baudrate

The serial speed of GPS chip is fixed by hardware using the pin __BAUD_SEL0__ and
__BAUD_SEL1__  visible on the schematic of GPS section. These pin are set at 3V3 
via R19 and R17 resistors. R20 and R18 are Not Mounted.

<img src="./DAISY-7-GPS.jpg" class="float">

This is the table of the serial speeds we can set changing the state of these pins:

| Speed    | BAUD_SEL0 | BAUD_SEL1 | R17 | R18 | R19 | R20 |
|----------|-----------|-----------|-----|-----|-----|-----|
| 4800     | 1         | 0         | No  | Yes | Yes | No  |
| 9600     | 0         | 0         | No  | Yes | No  | Yes |
| 38400    | 0         | 1         | Yes | No  | No  | Yes |
| 115200   | 1         | 1         | Yes | No  | Yes | No  |

#Buy

@shop='DAISY-7'
@shop='GPSANT'
@shop='FLAT-20CM'
@shop='DAISY-12'
@shop='IDC-PCB'