So in the final chapter of the long saga that has been connecting my Raspberry Pi to my Campus’s WiFi network, I needed a way to obtain the IP address of the Pi without using a display or a serial cable.
I’m actually pretty proud of this and I think it’s an elegant solution to a fairly annoying problem. Here’s a video of the system in action:
The program starts with three blinks. After that, the pattern goes as follows:
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Blink Blink Blink Pause = 3 Blink Blink Pause = 2 |
So
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Blink Blink Blink Pause Blink Blink Blink Blink Pause Blink = 341 |
Etc. Four short blinks indicate a 0 and six short blinks indicate a “.”
Once the address is fully read out, three long blinks will occur.
Here’s the code:
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import RPi.GPIO as GPIO ## Import GPIO library import time GPIO.setmode(GPIO.BCM) ## Use board pin numbering led = 20 button = 21 GPIO.setup(led, GPIO.OUT) ## Setup GPIO Pin 7 to OUT GPIO.setup(button, GPIO.IN) from subprocess import * while 1: if (GPIO.input(button)): ip = Popen("ip addr show wlan0 | grep inet | awk '{print $2}' | cut -d/ -f1", shell=True, stdout=PIPE).communicate()[0] for x in range(3): #three rapid blinks to indicate procedure is starting GPIO.output(led,True) time.sleep(.2) GPIO.output(led,False) time.sleep(.2) time.sleep(3) # followed by a delay for x in list(ip): time.sleep(4) #a long delay between characters if x.isdigit(): if (int(x) == 0): for x in range(4): #four rapid blinks indicate a 0 GPIO.output(led,True) time.sleep(.2) GPIO.output(led,False) time.sleep(.2) elif (int(x) != 0): for y in range(int(x)): GPIO.output(led,True) time.sleep(.5) GPIO.output(led,False) time.sleep(.5) elif (x == '.'): for x in range(6): #six rapid blinks indicate a . GPIO.output(led,True) time.sleep(.1) GPIO.output(led,False) time.sleep(.1) time.sleep(5) elif (x == '\n'): for x in range(3): #six rapid blinks indicate a '.' GPIO.output(led,True) time.sleep(2) GPIO.output(led,False) time.sleep(2) |
You can make it run every time the Pi boots with:
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crontab -e |
Add the following line:
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@reboot screen -d -m sudo python /path/to/script/Blink_IP.py |
And your good to go! You can now press the button any time the pi boots to get the IP address without connecting anything!
Or, hook up a speaker (or headphones) and have the TTS read out the IP?
This is probably a better solution, next time I re-work this code, I’ll integrate this functionality for sure.
any way to make this use the onboard status LED? i know it’s possible to toggle that on and off.. just not sure how difficult that would be to do.
Hey dan, thanks for commenting – I know it’s possible, but didn’t know how to do it at the time. Let me know if you try it!