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Merge pull request #149 from adafruit/eqep
WIP for rotary encoder support with eQEP
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‎Adafruit_BBIO/Encoder.py

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#!/usr/bin/python
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# ===========================================================================
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# Adafruit_BBIO.Encoder Class
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# ===========================================================================
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# refers to graycatlabs/PyBBIO/bbio/libraries/RotaryEncoder/rotary_encoder.py
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# BeagleBone must boot with cape-universal enabled
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# and load the cape-universala overlay in order to
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# use all the eQEP pins
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#
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# Install the latest Device Tree overlays:
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# ========================================
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# sudo apt-get upgrade bb-cape-overlays
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#
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# File: /boot/uEnv.txt
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# ====================
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# uname_r=4.4.62-ti-r99
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# cmdline=coherent_pool=1M quiet cape_universal=enable
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# cape_enable=bone_capemgr.enable_partno=cape-universala
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#
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# File: /sys/devices/platform/bone_capemgr/slots
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# ==============================================
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# 0: PF---- -1
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# 1: PF---- -1
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# 2: PF---- -1
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# 3: PF---- -1
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# 4: P-O-L- 0 Override Board Name,00A0,Override Manuf,cape-universala
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#
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# eqep0: P9_27, P9_92
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# ===================
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# config-pin P9_27 qep
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# config-pin P9_92 qep # alias for P9_42.1
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# cat /sys/devices/platform/ocp/48300000.epwmss/48300180.eqep/position
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#
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# eqep1: P8.33, P8.35
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# ===================
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# config-pin P8.33 qep
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# config-pin P8.35 qep
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# cat /sys/devices/platform/ocp/48302000.epwmss/48302180.eqep/position
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#
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# eqep2: P8.11, P8.12
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# ===================
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# config-pin P8.11 qep
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# config-pin P8.12 qep
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# cat /sys/devices/platform/ocp/48304000.epwmss/48304180.eqep/position
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#
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# alternate pins for eqep2 (mutually exclusive)
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# eqep2b: P8.41, P8.42
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# ====================
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# config-pin P8.41 qep
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# config-pin P8.42 qep
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# cat /sys/devices/platform/ocp/48304000.epwmss/48304180.eqep/position
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from subprocess import call
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import os
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class QEP :
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def __init__(self, channel=1, debug=False):
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self.channel = channel
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self.debug = debug
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def errMsg(self):
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print("Error accessing 0x%02X: Check your QEP channel" % self.address)
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return -1
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# example method from Adafruit_I2C
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# TODO: delete this
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# def write8(self, reg, value):
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# "Writes an 8-bit value to the specified register/address"
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# try:
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# self.bus.write_byte_data(self.address, reg, value)
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# if self.debug:
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# print("Rotary: Wrote 0x%02X to register 0x%02X" % (value, reg))
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# except IOError as err:
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# return self.errMsg()
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#
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#
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#if __name__ == '__main__':
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# try:
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# qep = Adafruit_BBIO.Encoder.QEP()
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# print("Default QEP channel is accessible")
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# except:
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# print("Error accessing default Rotary bus")
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class RotaryEncoder(object):
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# TODO: check that kernel 4.1+
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# TODO: use config-pin to set qep mode
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OCP_PATH = "/sys/devices/platform/ocp"
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_eqep_dirs = [
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'%s/48300000.epwmss/48300180.eqep' % OCP_PATH,
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'%s/48302000.epwmss/48302180.eqep' % OCP_PATH,
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'%s/48304000.epwmss/48304180.eqep' % OCP_PATH
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]
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EQEP0 = 0
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EQEP1 = 1
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EQEP2 = 2
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EQEP2b = 3
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def config_pin(self, pin):
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'''
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config_pin()
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Config pin for QEP
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'''
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result = call(["config-pin", pin, "qep"])
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print "config_pin> pin={0} result={1}".format(pin, result)
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return result
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def cat_file(self, path):
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'''
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cat_file()
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Print contents of file
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'''
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result = call(["cat", path])
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print "cat_file> path={0} result={1}".format(path, result)
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return result
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def __init__(self, eqep_num):
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'''
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RotaryEncoder(eqep_num)
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Creates an instance of the class RotaryEncoder.
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eqep_num determines which eQEP pins are set up.
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eqep_num can be: EQEP0, EQEP1, EQEP2 or EQEP2b based on which pins \
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the rotary encoder is connected to.
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'''
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print ">>>>>>>> TEST CALL BEGIN"
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###################################
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print ">>>>>> eqep0: P9_27, P9_92"
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pin = "P9_27"
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self.config_pin(pin)
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pin = "P9_92"
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self.config_pin(pin)
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path = "/sys/devices/platform/ocp/48300000.epwmss/48300180.eqep/position"
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self.cat_file(path);
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###################################
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print ">>>>>>> eqep1: P8.33, P8.35"
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pin = "P8.33"
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self.config_pin(pin)
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pin = "P8.35"
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self.config_pin(pin)
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path = "/sys/devices/platform/ocp/48302000.epwmss/48302180.eqep/position"
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self.cat_file(path);
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###################################
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print ">>>>>>> eqep2: P8.11, P8.12"
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pin = "P8.11"
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self.config_pin(pin)
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pin = "P8.12"
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self.config_pin(pin)
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path = "/sys/devices/platform/ocp/48304000.epwmss/48304180.eqep/position"
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self.cat_file(path);
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###################################
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print ">>>>>>> eqep2b: P8.41, P8.42"
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pin = "P8.41"
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self.config_pin(pin)
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pin = "P8.42"
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self.config_pin(pin)
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path = "/sys/devices/platform/ocp/48304000.epwmss/48304180.eqep/position"
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self.cat_file(path);
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###################################
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print ">>>>>>>> TEST CALL END"
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print("RotaryEncoder(): eqep_num: {0}".format(eqep_num))
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print("RotaryEncoder(): self._eqep_dirs[0]: {0}".format(self._eqep_dirs[0]))
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print("RotaryEncoder(): self._eqep_dirs[1]: {0}".format(self._eqep_dirs[1]))
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print("RotaryEncoder(): self._eqep_dirs[2]: {0}".format(self._eqep_dirs[2]))
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print("RotaryEncoder(): self._eqep_dirs[eqep_num: {0}]: {1}".format(eqep_num, self._eqep_dirs[eqep_num]))
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assert 0 <= eqep_num <= 3 , "eqep_num must be between 0 and 3"
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self.base_dir = self._eqep_dirs[eqep_num]
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print("RotaryEncoder(): self.base_dir: {0}".format(self.base_dir))
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self.enable()
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def enable(self):
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'''
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enable()
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Turns the eQEP hardware ON
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'''
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enable_file = "%s/enabled" % self.base_dir
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print("enable(): enable_file: {0}".format(enable_file))
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print("enable(): TODO: write 1 to enable_file")
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#return sysfs.kernelFileIO(enable_file, '1')
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def disable(self):
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'''
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disable()
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Turns the eQEP hardware OFF
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'''
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enable_file = "%s/enabled" % self.base_dir
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print("disable(): enable_file: {0}".format(enable_file))
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print("disable(): TODO: write 0 to enable_file")
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#return sysfs.kernelFileIO(enable_file, '0')
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def setAbsolute(self):
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'''
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setAbsolute()
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Set mode as Absolute
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The position starts at zero and is incremented or
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decremented by the encoder's movement
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'''
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mode_file = "%s/mode" % self.base_dir
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print("setAbsolute(): mode_file: {0}".format(mode_file))
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print("setAbsolute(): TODO: write 0 to mode_file")
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#return sysfs.kernelFileIO(mode_file, '0')
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def setRelative(self):
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'''
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setRelative()
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Set mode as Relative
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The position is reset when the unit timer overflows.
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'''
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mode_file = "%s/mode" % self.base_dir
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print("setRelative(): mode_file: {0}".format(mode_file))
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print("setRelative(): TODO: write 1 to mode_file")
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#return sysfs.kernelFileIO(mode_file, '1')
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def getMode(self):
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'''
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getMode()
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Returns the mode the eQEP hardware is in.
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'''
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mode_file = "%s/mode" % self.base_dir
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print("getMode(): mode_file: {0}".format(mode_file))
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print("getMode(): TODO: read mode_file")
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#return sysfs.kernelFileIO(mode_file)
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def getPosition(self):
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'''
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getPosition()
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Get the current position of the encoder.
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In absolute mode, this attribute represents the current position
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of the encoder.
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In relative mode, this attribute represents the position of the
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encoder at the last unit timer overflow.
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'''
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position_file = "%s/position" % self.base_dir
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print("getPosition(): position_file: {0}".format(position_file))
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position_handle = open(position_file, 'r')
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print("getPosition(): position_handle: {0}".format(position_handle))
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position = position_handle.read()
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print("getPosition(): position: {0}".format(position))
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#return sysfs.kernelFileIO(position_file)
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return position
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def setFrequency(self,freq):
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'''
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setFrequency(freq)
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Set the frequency in Hz at which the driver reports new positions.
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'''
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period_file = "%s/period" % self.base_dir
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print("setFrequency(): period_file: {0}".format(period_file))
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print("setFrequency(): freq: {0}".format(period_file))
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print("setFrequency(): freq: {0}".format(freq))
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print("setFrequency(): 1000000000/freq: {0}".format(1000000000/freq))
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print("setFrequency(): str(1000000000/freq)): {0}".format(str(1000000000/freq)))
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print("setFrequency(): TODO: set period_file: {0}".format(str(1000000000/freq)))
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#return sysfs.kernelFileIO(period_file, str(1000000000/freq))
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def setPosition(self,val):
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'''
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setPosition(value)
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Give a new value to the current position
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'''
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position_file = "%s/position" % self.base_dir
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#return sysfs.kernelFileIO(position_file, str(val))
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def zero(self):
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'''
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zero()s
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Set the current position to 0
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'''
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return self.setPosition(0)
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#"""
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# encoder_test.py
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# Rekha Seethamraju
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# An example to demonstrate the use of the eQEP library
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# for PyBBIO.
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# This example program is in the public domain.
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#"""
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#from bbio import *
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#from bbio.libraries.RotaryEncoder import RotaryEncoder
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#
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#encoder = RotaryEncoder(RotaryEncoder.EQEP2b)
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#
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#def setup():
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# encoder.setAbsolute()
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# encoder.zero()
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#
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#def loop():
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# print "encoder position : "+encoder.getPosition()
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# delay(1000)
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#
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#run(setup, loop)

‎doc/rotary-encoder-eqep-test.md

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I have documented how-to to enable all the eqep pins:
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https://github.com/adafruit/adafruit-beaglebone-io-python/commit/c418cdae9a2a2c0d52412561c0125b0d227af4eb
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BeagleBone must boot with cape-universal enabled and load the `cape-universala` overlay in order to
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use all the eQEP pins:
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### Install the latest Device Tree overlays:
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```
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sudo apt-get upgrade bb-cape-overlays
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```
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### File: /boot/uEnv.txt
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```
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uname_r=4.4.62-ti-r99
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cmdline=coherent_pool=1M quiet cape_universal=enable
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cape_enable=bone_capemgr.enable_partno=cape-universala
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```
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### File: /sys/devices/platform/bone_capemgr/slots
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```
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0: PF---- -1
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1: PF---- -1
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2: PF---- -1
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3: PF---- -1
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4: P-O-L- 0 Override Board Name,00A0,Override Manuf,cape-universala
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```
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### eqep0: P9_27, P9_92
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```
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config-pin P9_27 qep
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config-pin P9_92 qep # alias for P9_42.1
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cat /sys/devices/platform/ocp/48300000.epwmss/48300180.eqep/position
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```
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### eqep1: P8.33, P8.35
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```
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config-pin P8.33 qep
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config-pin P8.35 qep
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cat /sys/devices/platform/ocp/48302000.epwmss/48302180.eqep/position
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```
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### eqep2: P8.11, P8.12
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```
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config-pin P8.11 qep
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config-pin P8.12 qep
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cat /sys/devices/platform/ocp/48304000.epwmss/48304180.eqep/position
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```
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### eqep2b: P8.41, P8.42
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_alternate pins for eqep2 (mutually exclusive)_
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```
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config-pin P8.41 qep
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config-pin P8.42 qep
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cat /sys/devices/platform/ocp/48304000.epwmss/48304180.eqep/position
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```
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### TODO: implement in corresponding methods in `Encoder.py`

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