PyCubed boards come with a HopeRF RFM98PW high power (1W) LoRa radio tuned for 433 MHz.
<aside> ☝ Did you know For all intents and purposes, you can treat the RFM98 as a Semtech SX1276/8 radio.
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<aside> ⚠️ ALWAYS make sure an antenna is properly attached to the radio connector BEFORE powering the PyCubed board with any code that may try to use the radio. See the PyCubed page on Antennas for more details.
Failure to do so can permanently damage the radio. Read more about "reflected" transmitter energy here.
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Using the pycubed.py helper library:
from pycubed import cubesat
if cubesat.hardware['Radio1']:
while True:
packet = cubesat.radio1.receive()
if packet is None:
pass
else:
print('Received (raw bytes): {0}'.format(packet))
rssi = cubesat.radio1.rssi
print('Received signal strength: {0} dBm'.format(rssi))
Using the pycubed.py helper library:
from pycubed import cubesat
import time
count = 0
if cubesat.hardware['Radio1']:
while True:
count += 1
print('Sending Message...'+str(count))
cubesat.radio1.send('Hello World: '+str(count))
time.sleep(2)
The PyCubed boards come with an RFM98PW (433 MHz) installed meaning we can use a modified version of Adafruit's RFM9x CircuitPython library to easily operate the radio. The pycubed_rfm9x.py library is a fork of adafruit_rfm9x.py with some hardware-specific changes to make our lives easier.
The above examples use the default 433 MHz LoRa radio configuration as set by the RFM9x library. Carefully read through the pycubed_rfm9x.py library so you understand how the transmitter and receiver are configured.
pycubed_rfm9x.py library is part of PyCubed default libraries and can be found at /lib/pycubed_rfm9x.py with a PyCubed board plugged into your computer.<aside> 💡 Remember: All radio configuration and functions exist within this single plain-text file! When in doubt, look through this library first when troubleshooting your communications.
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Next, let's examine what the pycubed.py library is doing with the rfm9x library to initialize the hardware:
# Initialize radio(s)
try:
self.radio1 = adafruit_rfm9x.RFM9x(self.spi, self._rf_cs1, self._rf_rst1, 433.0)
self.hardware['Radio1'] = True
except Exception as e:
print('[ERROR][RADIO 1]',e)
We see that the pycubed.py library attempts to initialize BOTH radio positions, even through the board only ships with the Radio1 position populated. If we compare the above radio1 init to the class definition in the rfm9x library:
def __init__(self, spi, cs, reset, frequency, *, preamble_length=8,
high_power=True, baudrate=5000000):
it becomes clear that the the pycubed.py library sets a default frequency of 433.0 MHz and that default values are used for the preamble_length, high_power, and baud rate.
What if you wanted to change the frequency after the pycubed.py library has already initialized the hardware? That's easily achieved using the helpful setters/getters established in the pycubed_rfm9x.py library.
To change the frequency: