82 lines
3.3 KiB
Python
82 lines
3.3 KiB
Python
# MCP4018 digipot support (via bit-banging)
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#
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# Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
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#
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# This file may be distributed under the terms of the GNU GPLv3 license.
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class SoftwareI2C:
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def __init__(self, config, addr):
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self.addr = addr << 1
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self.update_pin_cmd = None
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# Lookup pins
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ppins = config.get_printer().lookup_object('pins')
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scl_pin = config.get('scl_pin')
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scl_params = ppins.lookup_pin(scl_pin, share_type='sw_scl')
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self.mcu = scl_params['chip']
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self.scl_pin = scl_params['pin']
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self.scl_main = scl_params.get('class')
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if self.scl_main is None:
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self.scl_main = scl_params['class'] = self
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self.scl_oid = self.mcu.create_oid()
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self.cmd_queue = self.mcu.alloc_command_queue()
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self.mcu.register_config_callback(self.build_config)
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else:
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self.scl_oid = self.scl_main.scl_oid
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self.cmd_queue = self.scl_main.cmd_queue
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sda_params = ppins.lookup_pin(config.get('sda_pin'))
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self.sda_oid = self.mcu.create_oid()
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if sda_params['chip'] != self.mcu:
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raise ppins.error("%s: scl_pin and sda_pin must be on same mcu" % (
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config.get_name(),))
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self.mcu.add_config_cmd("config_digital_out oid=%d pin=%s"
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" value=%d default_value=%d max_duration=%d" % (
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self.sda_oid, sda_params['pin'], 1, 1, 0))
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def build_config(self):
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self.mcu.add_config_cmd("config_digital_out oid=%d pin=%s value=%d"
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" default_value=%d max_duration=%d" % (
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self.scl_oid, self.scl_pin, 1, 1, 0))
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self.update_pin_cmd = self.mcu.lookup_command(
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"update_digital_out oid=%c value=%c", cq=self.cmd_queue)
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def i2c_write(self, msg):
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msg = [self.addr] + msg
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send = self.scl_main.update_pin_cmd.send
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# Send ack
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send([self.sda_oid, 0])
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send([self.scl_oid, 0])
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# Send bytes
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sda_last = 0
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for data in msg:
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# Transmit 8 data bits
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for i in range(8):
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sda_next = not not (data & (0x80 >> i))
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if sda_last != sda_next:
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sda_last = sda_next
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send([self.sda_oid, sda_last])
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send([self.scl_oid, 1])
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send([self.scl_oid, 0])
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# Transmit clock for ack
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send([self.scl_oid, 1])
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send([self.scl_oid, 0])
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# Send stop
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if sda_last:
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send([self.sda_oid, 0])
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send([self.scl_oid, 1])
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send([self.sda_oid, 1])
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class mcp4018:
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def __init__(self, config):
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self.i2c = SoftwareI2C(config, 0x2f)
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self.scale = config.getfloat('scale', 1., above=0.)
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self.start_value = config.getfloat('wiper',
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minval=0., maxval=self.scale)
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config.get_printer().register_event_handler("klippy:connect",
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self.handle_connect)
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def handle_connect(self):
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self.set_dac(self.start_value)
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def set_dac(self, value):
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val = int(value * 127. / self.scale + .5)
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self.i2c.i2c_write([val])
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def load_config_prefix(config):
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return mcp4018(config)
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