Controlling OpenPandora LEDs in Python

For those who don’t know me, I don’t like cell phones for a variety of reasons… but I do want a pocket computer, so I picked up what is essentially a pocket laptop made of cellphone parts named the OpenPandora.

Like normal-sized laptops, this nifty little device has a bunch of LEDs for indicating whether the WiFi is on, whether the battery is charging, and so on. Unlike many laptops, it was pretty easy to find documentation on how to control them in software.

For any other OpenPandora users who might be interested, here’s a little demo and helper library which makes the left bank of LEDs behave like KITT‘s scanner (without fading) while the charging indicator blinks.

I didn’t demo the partial brightness support on the power and charging LEDs but the helper library supports it.

The module docstring includes a few suggestions for where to go from here if you want to try something a little more challenging.

#!/usr/bin/python """Simple OpenPandora LED wrapper with demo By: Stephan Sokolow (deitarion/SSokolow) LEDs on the left are (in order): - sd1 - sd2 - wifi - bluetooth LEDs on the right are (in order): - (unpopulated) - (unpopulated) - charger - power LEDs on the left are on or off. LEDs on the right have variable brightness. SD card LEDs will only light if the corresponding SD card is present. Changelog: - 0.2: - LED.read() - LED.from_index(int) - Add epytext-format docstrings to the LED class. - Clean up module behaviour for easy import into your project. - Support the "with" statement and cleanup=True for easy LED resets. - Convert sudo wrapper into a properly reusable function. - Call "gksudo" if run outside a terminal or with redirected stdin. - Demonstrate using the signal module to exit cleanly on kill/killall/pkill - 0.1: - Basic demo functionality and write-capable wrapper class @note: Here are some ideas for more skilled users: - Write a program which opens LED file handles, then does all its work in an unprivileged child process. - Listen to L1 and R1 and use them to change the LEDs and play a sound so you can pretend your Pandora is a dollar-store raygun. - Display WiFi signal strength or battery charge on the LEDs - Listen on the microphone and make the LEDs a VU meter. @todo: Support for manipulating triggers and restoring them on exit. @todo: Make the demo even more CPU efficient by implementing an analogue to Javascript's setInterval rather than using a static sleep() interval. """ __author__ = "Stephan Sokolow" __license__ = "MIT" __version__ = "0.2" import contextlib, os, signal, sys def elevate(msg="Attempting to gain root privileges... "): """If the program isn't running as root, re-exec() via sudo. Otherwise, do nothing. @note: gksudo will be used if stdin has been redirected or the program is running in a terminal and X.org wasn't started via "startx". """ if os.geteuid() != 0: if sys.stdin.isatty(): print msg os.execvp('sudo', ['sudo'] + sys.argv) else: os.execvp('gksudo', ['gksudo', '-m', msg] + sys.argv) class LED(object): """Simple API wrapper for OpenPandora LEDs""" AVAILABLE_LEDS = ['sd1', 'sd2', 'wifi', 'bluetooth', 'charger', 'power'] state = None def __init__(self, name, cleanup=False): """ @param cleanup: Restore old LED values on C{close()} @type cleanup: C{bool} """ self.name = name self.fh = open('/sys/class/leds/pandora::%s/brightness' % name, 'wb+') self.cleanup = cleanup self.was = self.read() if not isinstance(self.was, int): raise Exception('%s: %s' % (self.name, self.was)) # Context manager support def __enter__(self): return self def __exit__(self, exc_type, exc_val, exc_tb): self.close() return False def close(self): """Close the file handle and optionally restore old LED values See L{__init__} for details. """ if self.cleanup and not self.fh.closed: #TODO: Make sure triggers are restored too self.write(self.was) self.fh.close() @classmethod def from_index(cls, idx, *args, **kwargs): """Instantiate a new LED by position on the device.""" return cls(cls.AVAILABLE_LEDS[idx], *args, **kwargs) def on(self): """Convenience wrapper to set full brightness.""" self.write(True) def off(self): """Convenience wrapper to set no brightness.""" self.write(False) def toggle(self): """Convenience wrapper to toggle 0/255 brightness.""" (self.off if self.state else self.on)() def read(self): """Read the current brightness @returns: A value in the range of 0 through 255 @rtype: C{int} """ self.fh.seek(0) return int(self.fh.read().strip('\n\0')) def write(self, val): """Set a new brightness @param val: C{True}, C{False}, or a number from 0 through 255. @type val: C{int()}-compatible """ if val is True: val = 255 else: # bool(False) == 0 so no need for a special case # Also, this ensures we error out on invalid input val = int(val) if not 0 <= val <= 255: raise ValueError("Need a boolean or integer from 0 through 255") self.state = bool(val) self.fh.write(str(val)) self.fh.flush() if __name__ == '__main__': elevate("Manipulating LEDs to requires root access.") import time # Easy-to-customize pseudo-constants SCANNER, BLINKER = range(0,4), 4 SCANNER_DELAY, BLINKER_DELAY = 0.1, 0.5 scanner = [LED.from_index(x, cleanup=True) for x in SCANNER] blinker = LED.from_index(BLINKER, cleanup=True) all = scanner + [blinker] def quit(a, b): # Remember, close() may reset LED states. [x.close() for x in all] sys.exit() # Clean up LEDs when exited via kill/killall/pkill for sig in ['SIGTERM', 'SIGHUP']: signal.signal(getattr(signal, sig), quit) pos, incr, max = -1, 1, len(scanner) - 1 now, last_move, last_toggle = 0, 0, 0 with contextlib.nested(*all): while True: now, then = time.time(), now if now - last_move > SCANNER_DELAY: last_move, pos = now, pos + incr [y.write(x == pos) for x, y in enumerate(scanner)] if (pos == max and incr > 0) or (pos == 0 and incr < 0): incr *= -1 if now - last_toggle > BLINKER_DELAY: blinker.toggle() last_toggle = now # Don't spin the CPU unnecessarily time.sleep(0.01)

Controlling OpenPandora LEDs in Python by Stephan Sokolow is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

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1 Response to Controlling OpenPandora LEDs in Python

JZ says:

2012-11-07 at 3:24

+1 for less usage of mobile phone..
haven’t change my samsung phone over 2 years as i don’t see the need to keep changing it.. the fanciful screen just drain your battery even more..

btw, thx for introducing OpenPandora..

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