Introduction

Simple programs can make a big difference! An XBee running small amounts of code can perform some pretty important tasks. Cryptic readings can be transformed into useful data, excess transmissions can be intelligently filtered out, modern sensors and actuators can be employed directly, operational logic can glue inputs and outputs together in an intelligent way.

Here are some useful MicroPython examples that should run within 12KB of RAM, useful even in a small sandboxed implementation. Required parts and a method for simulating limited RAM are noted below.

Examples

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Send “Hello World”

This example shows how to send some text data via an XBee in transparent mode.

1. SETUP: Connect the XBee (configured to factory defaults) as shown in the diagram below:
2.  PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Send Text Example v1.0 - XBee MicroPython from pyb import UART # load UART resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 uart.write('hello world!') # write data

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   # main.py -- Send Text Example v1.0 - XBee MicroPython from pyb import UART              # load UART resources uart = UART(4, baudrate=9600)     # create UART object on X1, X2 uart.write('hello world!')        # write data

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the text data. Each time you reset the pyboard, it sends “hello world!” one time to your computer. The results will look like this:
   

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Read, Transform and Send Value

This example shows how to read a sensor, transform that data into correct units, then send via an XBee in transparent mode.

1. SETUP: Connect the XBee (configured to factory defaults) and a TMP36 temperature sensor as shown in the diagram below. You can use the XBee pyboard skin to easily connect the radio module, and a small breadboard connected with jumper wires for the TMP36.
   
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Read Transform Send v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC while True: # loop continuously temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label pyb.delay(2000) # wait two seconds

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   # main.py -- Read Transform Send v1.0 - XBee MicroPython from pyb import Pin, ADC, UART       # load resources uart = UART(4, baudrate=9600)        # create UART object on X1, X2 pin = ADC(Pin('Y12'))                # configure Y12 for ADC while True:                          # loop continuously     temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform     uart.write(str(temp))               # write data     uart.write(' Celsius\n')            # write text label     pyb.delay(2000)                     # wait two seconds

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will look like this:
   

 

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Read, Transform and Send Only High Sensor Values

This example shows how to read a sensor, filter out low values, then send via an XBee in transparent mode.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Read Transform Send High Values v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC while True: # loop continuously temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform if (temp > 30): # only send high readings uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label pyb.delay(2000) # wait two seconds

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   # main.py -- Read Transform Send High Values v1.0 - XBee MicroPython from pyb import Pin, ADC, UART        # load resources uart = UART(4, baudrate=9600)         # create UART object on X1, X2 pin = ADC(Pin('Y12'))                 # configure Y12 for ADC while True:                           # loop continuously     temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform     if (temp > 30):                      # only send high readings         uart.write(str(temp))               # write data         uart.write(' Celsius\n')            # write text label     pyb.delay(2000)                      # wait two seconds

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show ONLY readings above the limit of 30 Celsius, no other data will be displayed:
   

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Read, Transform and Send Only High or Low Values

This example shows how to read a sensor, filter out mid-range values, then send any high or low values via an XBee in transparent mode.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Read Transform Send High or Low v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC while True: # loop continuously temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform if (temp > 30 or temp < 28): # only send high or low readings uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label pyb.delay(2000) # wait two seconds

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   # main.py -- Read Transform Send High or Low v1.0 - XBee MicroPython from pyb import Pin, ADC, UART        # load resources uart = UART(4, baudrate=9600)         # create UART object on X1, X2 pin = ADC(Pin('Y12'))                 # configure Y12 for ADC while True:                           # loop continuously     temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform     if (temp > 30 or temp < 28):         # only send high or low readings         uart.write(str(temp))                # write data         uart.write(' Celsius\n')             # write text label     pyb.delay(2000)                      # wait two seconds

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show ONLY readings below 28 Celsius or above 30 Celsius, no other data will be displayed:
   

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Send “Heartbeat” Sensor Data

This example shows how to send periodic “heartbeat” data values via an XBee in transparent mode. Used with filters or alarms to confirm normal operation.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Send Heartbeat Data v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC last_reading = 0 # take first reading right away while True: # loop continuously temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform if (pyb.millis() > last_reading): # only send data periodically last_reading = pyb.millis() + 60000 # schedule next reading for one minute later uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label

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   # main.py -- Send Heartbeat Data v1.0 - XBee MicroPython from pyb import Pin, ADC, UART        # load resources uart = UART(4, baudrate=9600)         # create UART object on X1, X2 pin = ADC(Pin('Y12'))                 # configure Y12 for ADC last_reading = 0                      # take first reading right away while True: # loop continuously     temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform     if (pyb.millis() > last_reading):    # only send data periodically         last_reading = pyb.millis() + 60000  # schedule next reading for one minute later         uart.write(str(temp))                # write data         uart.write(' Celsius\n')             # write text label

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show data readings once per minute, though in typical use it might be set to daily or even weekly.
   

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Send “Heartbeat” with Min and Max

This example shows how to send periodic “heartbeat” data values with min and max for the period, via an XBee in transparent mode.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Send Heartbeat with Min and Max v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC last_reading = 0 # take first reading right away while True: # loop continuously temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform try: if (max_temp <= temp): max_temp = temp # keep max up-to-date if (min_temp >= temp): min_temp = temp # keep min up-to-date except NameError: # if variables don't exist... max_temp = min_temp = temp # ...reset min and max if (pyb.millis() > last_reading): # only send data periodically last_reading = pyb.millis() + 60000 # schedule next reading for one minute later uart.write(str(temp)) # write data uart.write(' Celsius now\n') # write text label uart.write(str(min_temp)) # write min data uart.write(' Celsius min\n') # write text label uart.write(str(max_temp)) # write max data uart.write(' Celsius max\n') # write text label del max_temp, min_temp # delete min and max for next run

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   # main.py -- Send Heartbeat with Min and Max v1.0 - XBee MicroPython from pyb import Pin, ADC, UART       # load resources uart = UART(4, baudrate=9600)        # create UART object on X1, X2 pin = ADC(Pin('Y12'))                # configure Y12 for ADC last_reading = 0                     # take first reading right away while True:                          # loop continuously     temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform     try:         if (max_temp <= temp): max_temp = temp # keep max up-to-date         if (min_temp >= temp): min_temp = temp # keep min up-to-date     except NameError:                   # if variables don't exist...         max_temp = min_temp = temp          # ...reset min and max     if (pyb.millis() > last_reading):   # only send data periodically         last_reading = pyb.millis() + 60000 # schedule next reading for one minute later         uart.write(str(temp))               # write data         uart.write(' Celsius now\n')        # write text label         uart.write(str(min_temp))           # write min data         uart.write(' Celsius min\n')        # write text label         uart.write(str(max_temp))           # write max data         uart.write(' Celsius max\n')        # write text label         del max_temp, min_temp              # delete min and max for next run

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show data readings once per minute, with the minimum and maximum values during that period.
   

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Aggregate 10 Samples Then Send Batch

This example shows how to aggregate data before sending in a batch, via an XBee in transparent mode.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Aggregate Then Send 10 Values v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC period = 60000 # length between sends samples = 10 # number of samples in a send while True: # loop continuously readings=[] # create a list to store readings for i in range(samples): # sample the right number of times temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform readings.append(temp) # put the sample in the list pyb.delay(int(period/samples)) # wait until the next sample for value in readings: # iterate through the list uart.write(str(value)) # write data uart.write(' Celsius\n') # write text label del(readings) # delete list to prepare for next run

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   # main.py -- Aggregate Then Send 10 Values v1.0 - XBee MicroPython from pyb import Pin, ADC, UART     # load resources uart = UART(4, baudrate=9600)      # create UART object on X1, X2 pin = ADC(Pin('Y12'))              # configure Y12 for ADC period = 60000                     # length between sends samples = 10                       # number of samples in a send while True:                        # loop continuously     readings=[]                       # create a list to store readings     for i in range(samples):          # sample the right number of times         temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform         readings.append(temp)             # put the sample in the list         pyb.delay(int(period/samples))    # wait until the next sample     for value in readings:            # iterate through the list         uart.write(str(value))            # write data         uart.write(' Celsius\n')          # write text label         del(readings)                     # delete list to prepare for next run

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show nothing for a minute, then you should see 10 data readings, sent all at once.
   

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Aggregate Values Then Send Average

This example shows how to aggregate data before sending an average of the data, via an XBee in transparent mode.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Aggregate Then Send Average v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC period = 60000 # length between sends samples = 10 # number of samples in a send while True: # loop continuously readings=[] # create a list to store readings for i in range(samples): # sample the right number of times temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform readings.append(temp) # put the sample in the list pyb.delay(int(period/samples)) # wait until the next sample uart.write(str(sum(readings)/samples)) # write averaged data uart.write(' Celsius avg.\n') # write text label del(readings) # delete list to prepare for next run

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   # main.py -- Aggregate Then Send Average v1.0 - XBee MicroPython from pyb import Pin, ADC, UART      # load resources uart = UART(4, baudrate=9600)       # create UART object on X1, X2 pin = ADC(Pin('Y12'))               # configure Y12 for ADC period = 60000                      # length between sends samples = 10                        # number of samples in a send while True:                         # loop continuously     readings=[]                        # create a list to store readings     for i in range(samples):           # sample the right number of times         temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform         readings.append(temp)              # put the sample in the list         pyb.delay(int(period/samples))     # wait until the next sample     uart.write(str(sum(readings)/samples)) # write averaged data     uart.write(' Celsius avg.\n')      # write text label     del(readings)                    # delete list to prepare for next run

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show nothing for a minute, then you should see an average of 10 samples.
   

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Suppress Duplicate Data

This example shows how to suppress sending too many duplicate readings, via an XBee in transparent mode.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Suppress Duplicate Data v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 pin = ADC(Pin('Y12')) # configure Y12 for ADC period = 60000 # length between mandatory sends percent_dif = 10 # percent change that triggers immediate send last_temp = 0 # stores last sent sensor value start_time = pyb.millis() # mark initial start time while True: # loop continuously temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform if pyb.millis() - start_time > period: # when it's madatory send time... start_time = pyb.millis() # update start time uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label last_temp = temp # update last sensor value if abs(last_temp - temp) > last_temp * percent_dif/100: # significant changes trigger immediate send start_time = pyb.millis() # update start time uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label last_temp = temp # update last sensor value pyb.delay(1000) # wait between samples

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   # main.py -- Suppress Duplicate Data v1.0 - XBee MicroPython from pyb import Pin, ADC, UART   # load resources uart = UART(4, baudrate=9600)    # create UART object on X1, X2 pin = ADC(Pin('Y12'))            # configure Y12 for ADC period = 60000                   # length between mandatory sends percent_dif = 10              # percent change that triggers immediate send last_temp = 0                    # stores last sent sensor value start_time = pyb.millis()        # mark initial start time while True:                      # loop continuously     temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform     if pyb.millis() - start_time > period: # when it's madatory send time...         start_time = pyb.millis()       # update start time         uart.write(str(temp))           # write data         uart.write(' Celsius\n')        # write text label         last_temp = temp                # update last sensor value     if abs(last_temp - temp) > last_temp * percent_dif/100: # significant changes trigger immediate send         start_time = pyb.millis()       # update start time         uart.write(str(temp))           # write data         uart.write(' Celsius\n')        # write text label         last_temp = temp                # update last sensor value     pyb.delay(1000)                 # wait between samples

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show readings every minute, with changes greater than 10% triggering an immediate reading.
   

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Local Control

This example shows how to turn local input into local actions, with alert messages about important events delivered remotely.

1. SETUP: Connect the XBee (configured to factory defaults), an LED and a sensor switch as shown below. You can use the XBee pyboard skin to easily connect the radio module, and a small breadboard connected with jumper wires for the LED, the switch and their resistors.
   
2.  PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Local Control v1.0 - XBee MicroPython from pyb import Pin, ADC, UART # load resources uart = UART(4, baudrate=9600) # create UART object on X1, X2 sensor_pin = Pin('Y9', Pin.IN) # configure Y9 for digital input alarm_pin = Pin('Y10', Pin.OUT_PP) #configure Y10 for digital output delay = 60000 # delay in milliseconds before triggering alarm while True: # loop continuously if sensor_pin.value() == 1: # if sensor input goes high start_time = pyb.millis() # mark the time while sensor_pin.value() == 1: # keep monitoring inupt if pyb.millis() - start_time >= delay: # if sensor remains on for delay time alarm_pin.high() # turn on the local alarm if not (pyb.millis() - start_time + delay) % 60000: # once a minute uart.write('Alarm\n') # send a text alert else: # when sensor is low alarm_pin.low() # turn alarm off

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   # main.py -- Local Control v1.0 - XBee MicroPython from pyb import Pin, ADC, UART    # load resources uart = UART(4, baudrate=9600)     # create UART object on X1, X2 sensor_pin = Pin('Y9', Pin.IN)    # configure Y9 for digital input alarm_pin = Pin('Y10', Pin.OUT_PP) #configure Y10 for digital output delay = 60000             # delay in milliseconds before triggering alarm while True:                       # loop continuously     if sensor_pin.value() == 1:      # if sensor input goes high         start_time = pyb.millis()       # mark the time         while sensor_pin.value() == 1:   # keep monitoring inupt             if pyb.millis() - start_time >= delay: # if sensor remains on for delay time                 alarm_pin.high()                 # turn on the local alarm                 if not (pyb.millis() - start_time + delay) % 60000: # once a minute                     uart.write('Alarm\n')            # send a text alert                 else:                            # when sensor is low                     alarm_pin.low()                  # turn alarm off

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the alarm alerts. After the switch has been pressed continuously for 60 seconds, the alarm light will turn on. You will receive text alerts in the terminal every minute until the button is released.
   

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Transform UART

This example shows how to accept incoming text strings and transform them to different outgoing text strings.

1. SETUP: Use the hello world setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Transform UART v1.0 - XBee MicroPython from pyb import UART # load UART resources uart = UART(4, baudrate=9600) # create UART object for radio while True: # loop continuously if uart.any() >= 3: # if there's 3 or more bytes to read if 'hw' in uart.readline(): # look for 'hw' input with a linefeed from host uart.write('hello world!\n') # write transformed output to radio

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   # main.py -- Transform UART v1.0 - XBee MicroPython from pyb import UART            # load UART resources uart = UART(4, baudrate=9600)   # create UART object for radio while True:                     # loop continuously     if uart.any() >= 3:            # if there's 3 or more bytes to read         if 'hw' in uart.readline(): # look for 'hw' input with a linefeed from host             uart.write('hello world!\n')   # write transformed output to radio

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Next, using a terminal program like XCTUor CoolTerm, type “hw” into the active window followed by a return. You should receive “hello world” back as shown below. All text input that doesn’t contain “hw” should be ignored.
   

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Respond to Data Request

This example shows how to accept an incoming serial text command and respond with a sensor data reading.

1. SETUP: Use the basic sensing setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Respond to Data Request v1.0 - XBee MicroPython from pyb import UART, Pin, ADC # load resources uart = UART(4, baudrate=9600) # create UART object pin = ADC(Pin('Y12')) # configure Y12 for ADC while True: if uart.any() >= 5: # if there's 5 or more bytes to read if 'temp' in uart.readline(): # look for sensor request temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform uart.write(str(temp)) # write data uart.write(' Celsius\n') # write text label

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   # main.py -- Respond to Data Request v1.0 - XBee MicroPython from pyb import UART, Pin, ADC     # load resources uart = UART(4, baudrate=9600)      # create UART object pin = ADC(Pin('Y12'))              # configure Y12 for ADC while True:     if uart.any() >= 5:               # if there's 5 or more bytes to read         if 'temp' in uart.readline():     # look for sensor request             temp = (int((pin.read() * (3300/4096)) - 500) / 10) # read analog TMP36 and transform             uart.write(str(temp))             # write data             uart.write(' Celsius\n')          # write text label

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Next, using a terminal program like XCTUor CoolTerm, type “temp” into the active window followed by a return. You should receive a temperature reading back as shown below. All text input that doesn’t contain “temp” should be ignored.
   

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Control Pin via UART

This example shows how to turn an LED on and off using serial text input, via an XBee in transparent mode.

1. SETUP: Connect the XBee (configured to factory defaults), and an LED as shown below. You can use the XBee pyboard skin to easily connect the radio module, and a small breadboard connected with jumper wires for the LED and resistor.
   
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Control Pin via UART v1.0 - XBee MicroPython from pyb import UART, Pin # load resources uart = UART(4, baudrate=9600) # create UART object output_pin = Pin('Y10', Pin.OUT_PP) #configure Y10 for digital output while True: # loop continuously if uart.any() >= 3: # if there's 3 or more bytes to read incoming = uart.readline() # read from the UART if 'on' in incoming: # look for 'on' command output_pin.high() # turn on the LED uart.write('pin on\n') # write status if 'off' in incoming: # look for 'off' command output_pin.low() # turn off the LED uart.write('pin off\n') # write status

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   # main.py -- Control Pin via UART v1.0 - XBee MicroPython from pyb import UART, Pin           # load resources uart = UART(4, baudrate=9600)       # create UART object output_pin = Pin('Y10', Pin.OUT_PP) #configure Y10 for digital output while True:                         # loop continuously     if uart.any() >= 3:               # if there's 3 or more bytes to read         incoming = uart.readline()         # read from the UART         if 'on' in incoming:               # look for 'on' command             output_pin.high()                  # turn on the LED             uart.write('pin on\n')             # write status         if 'off' in incoming:              # look for 'off' command             output_pin.low()                   # turn off the LED             uart.write('pin off\n')            # write status

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Next, using a terminal program like XCTUor CoolTerm, type “on” into the active window followed by a return. You should receive “pin on” back as shown below, and the LED should turn on. Type “off” followed by a return to douse the LED and receive “pin off” as confirmation. All text input that doesn’t contain “on” or “off” should be ignored.
   

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Basic I2C Sensor Read

This example shows how to do a very basic read an I2C sensor (the BMP180), via an XBee in transparent mode.

1. SETUP: Connect the XBee (configured to factory defaults), and the BMP180 as shown below (same connections as older BMP085). You can use the XBee pyboard skin to easily connect the radio module, and a small breadboard connected with jumper wires for the BMP180.
   
2. PROGRAM: Load the code sample into your pyboard’s main.py file
   
   # main.py -- Basic I2C Sensor Read - XBee MicroPython from pyb import UART, Pin, I2C # load resources from struct import unpack # resource to unpack readings uart = UART(4, baudrate=9600) # create UART object i2c = I2C(2, I2C.MASTER) # create I2C object on bus 2 while True: # loop continuously i2c.mem_write(0x2E, 0x77, 0xF4, timeout=1000) # writing 2E to slave 0x77's 0xF4 address initiates a temp. reading pyb.delay(5) # wait > 4.5 milliseconds for reading temp = i2c.mem_read(2, 0x77, 0xF6) # read 2 bytes starting memory address 0xF6 of slave 0x77 temp = unpack(">h", temp)[0] # unpack the readings as a big endian short uart.write(str(temp)) # write data uart.write(' uncalibrated temperature\n') # write label pyb.delay(1000) # wait a second between samples

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   # main.py -- Basic I2C Sensor Read - XBee MicroPython from pyb import UART, Pin, I2C     # load resources from struct import unpack          # resource to unpack readings uart = UART(4, baudrate=9600)      # create UART object i2c = I2C(2, I2C.MASTER)           # create I2C object on bus 2 while True:                        # loop continuously     i2c.mem_write(0x2E, 0x77, 0xF4, timeout=1000) # writing 2E to slave 0x77's 0xF4 address initiates a temp. reading     pyb.delay(5)                      # wait > 4.5 milliseconds for reading     temp = i2c.mem_read(2, 0x77, 0xF6) # read 2 bytes starting memory address 0xF6 of slave 0x77     temp = unpack(">h", temp)[0]   # unpack the readings as a big endian short     uart.write(str(temp))             # write data     uart.write(' uncalibrated temperature\n') # write label     pyb.delay(1000)                   # wait a second between samples

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show raw, uncalibrated numbers from the temperature sensor since that’s all this example asks for. Warm the sensor with your hand to watch the numbers increase, then let it cool to see them decrease:
   

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Full BMP180 I2C

This example shows how to fully read an I2C sensor (the BMP180), via an XBee in transparent mode.

1. SETUP: Use the BMP180 setup.
2. PROGRAM: Load the code sample into your pyboard’s main.py file, then download the BMP180 library and put it into the same directory.
   
   # main.py -- Full BMP180 I2C - XBee MicroPython from pyb import UART # load resources from bmp180 import BMP180 # load library for BMP180 bmp180 = BMP180() # create BMP180 object bmp180.oversample_sett = 2 # take two samples for each reported bmp180.baseline = 101325 # set baseline altitude uart = UART(4, baudrate=9600) # create UART object while True: # loop continuously temp = bmp180.temperature # take a calibrated temp reading p = bmp180.pressure # take a calibrated pressure reading altitude = bmp180.altitude # take a calibrated altitude reading uart.write('temp:') # write data and labels uart.write(str(temp)) uart.write(' pressure:') uart.write(str(p)) uart.write(' altitude:') uart.write(str(altitude)) uart.write('\n') pyb.delay(1000) # wait a second between samples

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   # main.py -- Full BMP180 I2C - XBee MicroPython from pyb import UART          # load resources from bmp180 import BMP180     # load library for BMP180 bmp180 = BMP180()             # create BMP180 object bmp180.oversample_sett = 2    # take two samples for each reported bmp180.baseline = 101325      # set baseline altitude uart = UART(4, baudrate=9600) # create UART object while True:                   # loop continuously     temp = bmp180.temperature    # take a calibrated temp reading     p = bmp180.pressure          # take a calibrated pressure reading     altitude = bmp180.altitude   # take a calibrated altitude reading     uart.write('temp:')          # write data and labels     uart.write(str(temp))     uart.write(' pressure:')     uart.write(str(p))     uart.write(' altitude:')     uart.write(str(altitude))     uart.write('\n')     pyb.delay(1000)              # wait a second between samples

3. RESULTS: Connect a second XBee, also configured to factory defaults, to your computer. Then use a terminal program like XCTU or CoolTerm to receive the sensor data. The results will show calibrated temperature, pressure and altitude readings. Warm the sensor with your hand, and raise or lower it by a few meters to change the readings:
   

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Resources

Simulating Limited RAM

To simulate 12KB of total RAM on the 192KB pyboard, use this block of code at the start of your program, or imported  in a config.py file.