HAB monitoring Post#4 (Using UART in BBB)

In this week's post, I will be using a transceiver connected to a UART of BBB to collect data.

• Cool features of Beaglebone Black rev C
• Hardware setup
• Using UART of BBB

Cool features of Beaglebone Black:

     This is the first time I use BBB and below are some of the cool features I love during the first few days of use. This board is amazing and I'm sure there will be more features to enjoy.

1. Processor. 1GHz chip with 512 of DDR3 RAM
2. OnBoard Flash Memory. Referred to as eMMC with pre-installed Debian OS. With this, I was able to use BBB out of the box even without MicroSD card and the change from Angstrom to Debian makes my transition from RaspPi easier.
3. Mini USB Port. This allows you to access BBB through your computer aside from the ethernet port. Since I frequently change IP address of eth0 of the board, the mini usb port gives me a fix way to access BBB (BTW through 192.168.7.2).
4. Expansion headers. There are two headers labeled P9 and P8 for GPIO, I2C, SPI, UART, CAN, PWM, ADC

Hardware setup:

The materials used in this post including Arduino board, shields and XBee radios are just to test the UART of BBB and will not be used in the design challenge instead they will be replaced by MSP4305969 and CC110L. The left figure above is the source of data. I am using Arduino Mega with Wireless shield. The transceiver is XBee series 1. The potentiometer is to simulate analog sensor and connected to A5 of the Arduino board.

The right figure is a Beaglebone Black conncted to my computer. The XBee s1 is attached to an XBee shield for Arduino but this shield is just used as breakout board in this setup.

• XBee pin 1 is Vcc connected to P9_3 of BBB (3.3V source) Caution: XBee operates at 3.3V and check the BBB pin mapping below
• XBee pin 10 is GND connected to P9_1 of BBB (GND)
• XBee pin 2 is Dout connected to P9_22 of BBB (UART2_RXD)
• XBee pin 3 is Din connected to P9_21 of BBB (UART2_TXD)

Using UART of Beaglebone Black:

Pin mapping of BBB with UART pins highlight

http://beagleboard.org/Support/bone101

1. To use a particular UART, it has to be enabled first:

# echo BB-UART2 >> /sys/devices/bone_capemgr.9/slots

2. Before the code, you have to install xbee library for python:

#wget https://python-xbee.googlecode.com/files/XBee-2.1.0.tar.gz
#tar -xvf XBee-2.1.0.tar.gz
#cd XBee-2.1.0
#python ./setup.py install

3. Create a python file and give it a name:

# nano xbee_bbb.py

4. Code:

import serial
import time
from xbee import XBee

serial_port = serial.Serial('dev/ttyO2', 9600)

def print_data(data):
     if 'source_addr' in data:
          hex_data = data['rf_data']
          sensor_data = map(ord, hex_data)
          print 'D.O. = %d'%sensor_data[0]
          print sensor_data[1]
          print sensor_data[2]
          print sensro_data[3]

xbee = XBee(serial_port, callback = print_data)
while True:
     try:
          time.sleep(0.01)
     except KeyboardInterrupt:
          break
xbee.halt()
serial_port.close()

Note: Check the table above for device name if you want to use other UART

5. Run the code:

#python xbee_bbb.py

Here is the output:

6. Turn the potentiometer connected to A5 of Arduino to see change of value for  D.O. The other 3 values below D.O. are analog readings from A4,A3 and A2 of Arduino and these will be just random values since nothing is connected to these ports.

I am supposed to publish the received data by the BBB to AirVantage cloud but I am having trouble with proxy configuration since my device is behind university proxy.

I will update this post or have it another post with data in the cloud as soon as I'm able to figure out my proxy configuration.

I am able to update and install in my BBB but sending data to cloud fails. Any help on this is much appreciated. Thanks.