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duty_cycle bug fixed #1

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duty_cycle bug fixed #1

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118 changes: 63 additions & 55 deletions syspwm.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,61 +22,69 @@ class SysPWMException(Exception):
# /sys/ pwm interface described here: http://www.jumpnowtek.com/rpi/Using-the-Raspberry-Pi-Hardware-PWM-timers.html
class SysPWM(object):

chippath = "/sys/class/pwm/pwmchip0"

def __init__(self,pwm):
self.pwm=pwm
self.pwmdir="{chippath}/pwm{pwm}".format(chippath=self.chippath,pwm=self.pwm)
if not self.overlay_loaded():
raise SysPWMException("Need to add 'dtoverlay=pwm-2chan' to /boot/config.txt and reboot")
if not self.export_writable():
raise SysPWMException("Need write access to files in '{chippath}'".format(chippath=self.chippath))
if not self.pwmX_exists():
self.create_pwmX()
return

def overlay_loaded(self):
return os.path.isdir(self.chippath)

def export_writable(self):
return os.access("{chippath}/export".format(chippath=self.chippath), os.W_OK)

def pwmX_exists(self):
return os.path.isdir(self.pwmdir)

def echo(self,m,fil):
#print "echo {m} > {fil}".format(m=m,fil=fil)
with open(fil,'w') as f:
f.write("{m}\n".format(m=m))

def create_pwmX(self):
pwmexport = "{chippath}/export".format(chippath=self.chippath)
self.echo(self.pwm,pwmexport)

def enable(self,disable=False):
enable = "{pwmdir}/enable".format(pwmdir=self.pwmdir)
num = 1
if disable:
num = 0
self.echo(num,enable)

def disable(self):
return self.enable(disable=True)

def set_duty_cycle(self,milliseconds):
# /sys/ iface, 2ms is 2000000
# gpio cmd, 2ms is 200
dc = int(milliseconds * 1000000)
duty_cycle = "{pwmdir}/duty_cycle".format(pwmdir=self.pwmdir)
self.echo(dc,duty_cycle)

def set_frequency(self,hz):
per = (1 / float(hz))
per *= 1000 # now in milliseconds
per *= 1000000 # now in.. whatever
per = int(per)
period = "{pwmdir}/period".format(pwmdir=self.pwmdir)
self.echo(per,period)
__chippath = "/sys/class/pwm/pwmchip0"
__pwm = None
__pwmdir = None
__period_ns = 0
__frequency_hz = 0
__duty_cycle = 0

def __init__(self,pwm,frequency):
self.__pwm=pwm
self.__pwmdir="{chippath}/pwm{pwm}".format(chippath=self.__chippath,pwm=self.__pwm)
if not self.overlay_loaded():
raise SysPWMException("Need to add 'dtoverlay=pwm-2chan' to /boot/config.txt and reboot")
if not self.export_writable():
raise SysPWMException("Need write access to files in '{chippath}'".format(chippath=self.__chippath))
if not self.pwmX_exists():
self.create_pwmX()
self.set_frequency(frequency)
return

def overlay_loaded(self):
return os.path.isdir(self.__chippath)

def export_writable(self):
return os.access("{chippath}/export".format(chippath=self.__chippath), os.W_OK)

def pwmX_exists(self):
return os.path.isdir(self.__pwmdir)

def echo(self,m,fil):
#print "echo {m} > {fil}".format(m=m,fil=fil)
with open(fil,'w') as f:
f.write("{m}\n".format(m=m))

def create_pwmX(self):
pwmexport = "{chippath}/export".format(chippath=self.__chippath)
self.echo(self.__pwm,pwmexport)

def enable(self,disable=False):
enable = "{pwmdir}/enable".format(pwmdir=self.__pwmdir)
num = 1
if disable:
num = 0
self.echo(num,enable)

def disable(self):
return self.enable(disable=True)

def set_duty_cycle(self,duty_cycle):
self.__duty_cycle = max(0, min(1, duty_cycle))
duty_cycle_ns = int(self.__duty_cycle*self.__period_ns)
path = "{pwmdir}/duty_cycle".format(pwmdir=self.__pwmdir)
self.echo(duty_cycle_ns, path)

def set_frequency(self,frequency):
old_dc = self.__duty_cycle
self.set_duty_cycle(0)

self.__frequency = int(frequency)
self.__period_ns = int((1.0/self.__frequency)*1e9)

self.set_duty_cycle(old_dc)
path = "{pwmdir}/period".format(pwmdir=self.__pwmdir)
self.echo(self.__period_ns,path)

if __name__ == "__main__":
from time import sleep
Expand Down