diff options
| -rw-r--r-- | config/example-extras.cfg | 25 | ||||
| -rwxr-xr-x | docs/Features.md | 2 | ||||
| -rw-r--r-- | klippy/extras/mcp4018.py | 81 |
3 files changed, 107 insertions, 1 deletions
diff --git a/config/example-extras.cfg b/config/example-extras.cfg index 14ea6391..5451eac5 100644 --- a/config/example-extras.cfg +++ b/config/example-extras.cfg @@ -778,6 +778,31 @@ # default is to not scale the 'channel_x' parameters. +# Statically configured MCP4018 digipot connected via two gpio "bit +# banging" pins (one may define any number of sections with an +# "mcp4018" prefix). +#[mcp4018 my_digipot] +#scl_pin: +# The SCL "clock" pin. This parameter must be provided. +#sda_pin: +# The SDA "data" pin. This parameter must be provided. +#wiper: +# The value to statically set the given MCP4018 "wiper" to. This is +# typically set to a number between 0.0 and 1.0 with 1.0 being the +# highest resistance and 0.0 being the lowest resistance. However, +# the range may be changed with the 'scale' parameter (see +# below). This parameter must be provided. +#scale: +# This parameter can be used to alter how the 'wiper' parameter is +# interpreted. If provided, then the 'wiper' parameter should be +# between 0.0 and 'scale'. This may be useful when the MCP4018 is +# used to set stepper voltage references. The 'scale' can be set to +# the equivalent stepper amperage if the MCP4018 is at its highest +# resistance, and then the 'wiper' parameter can be specified using +# the desired amperage value for the stepper. The default is to not +# scale the 'wiper' parameter. + + # Configure an SX1509 I2C to GPIO expander. Due to the delay incurred # by I2C communication you should NOT use SX1509 pins as stepper enable, # step or dir pins or any other pin that requires fast bit-banging. They diff --git a/docs/Features.md b/docs/Features.md index 9249f612..43a0cf89 100755 --- a/docs/Features.md +++ b/docs/Features.md @@ -95,7 +95,7 @@ Klipper supports many standard 3d printer features: * Support for run-time configuration of TMC2130, TMC2208, TMC2224, and TMC2660 stepper motor drivers. There is also support for current control of traditional stepper drivers via AD5206, MCP4451, MCP4728, - and PWM pins. + MCP4018, and PWM pins. * Support for common LCD displays attached directly to the printer. A default menu is also available. diff --git a/klippy/extras/mcp4018.py b/klippy/extras/mcp4018.py new file mode 100644 index 00000000..f53024b9 --- /dev/null +++ b/klippy/extras/mcp4018.py @@ -0,0 +1,81 @@ +# MCP4018 digipot support (via bit-banging) +# +# Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net> +# +# This file may be distributed under the terms of the GNU GPLv3 license. + +class SoftwareI2C: + def __init__(self, config, addr): + self.addr = addr << 1 + self.update_pin_cmd = None + # Lookup pins + ppins = config.get_printer().lookup_object('pins') + scl_pin = config.get('scl_pin') + scl_params = ppins.lookup_pin(scl_pin, share_type='sw_scl') + self.mcu = scl_params['chip'] + self.scl_pin = scl_params['pin'] + self.scl_main = scl_params.get('class') + if self.scl_main is None: + self.scl_main = scl_params['class'] = self + self.scl_oid = self.mcu.create_oid() + self.cmd_queue = self.mcu.alloc_command_queue() + self.mcu.register_config_callback(self.build_config) + else: + self.scl_oid = self.scl_main.scl_oid + self.cmd_queue = self.scl_main.cmd_queue + sda_params = ppins.lookup_pin(config.get('sda_pin')) + self.sda_oid = self.mcu.create_oid() + if sda_params['chip'] != self.mcu: + raise ppins.error("%s: scl_pin and sda_pin must be on same mcu" % ( + config.get_name(),)) + self.mcu.add_config_cmd("config_digital_out oid=%d pin=%s" + " value=%d default_value=%d max_duration=%d" % ( + self.sda_oid, sda_params['pin'], 1, 1, 0)) + def build_config(self): + self.mcu.add_config_cmd("config_digital_out oid=%d pin=%s value=%d" + " default_value=%d max_duration=%d" % ( + self.scl_oid, self.scl_pin, 1, 1, 0)) + self.update_pin_cmd = self.mcu.lookup_command( + "update_digital_out oid=%c value=%c", cq=self.cmd_queue) + def i2c_write(self, msg): + msg = [self.addr] + msg + send = self.scl_main.update_pin_cmd.send + # Send ack + send([self.sda_oid, 0]) + send([self.scl_oid, 0]) + # Send bytes + sda_last = 0 + for data in msg: + # Transmit 8 data bits + for i in range(8): + sda_next = not not (data & (0x80 >> i)) + if sda_last != sda_next: + sda_last = sda_next + send([self.sda_oid, sda_last]) + send([self.scl_oid, 1]) + send([self.scl_oid, 0]) + # Transmit clock for ack + send([self.scl_oid, 1]) + send([self.scl_oid, 0]) + # Send stop + if sda_last: + send([self.sda_oid, 0]) + send([self.scl_oid, 1]) + send([self.sda_oid, 1]) + +class mcp4018: + def __init__(self, config): + self.i2c = SoftwareI2C(config, 0x2f) + self.scale = config.getfloat('scale', 1., above=0.) + self.start_value = config.getfloat('wiper', + minval=0., maxval=self.scale) + config.get_printer().register_event_handler("klippy:connect", + self.handle_connect) + def handle_connect(self): + self.set_dac(self.start_value) + def set_dac(self, value): + val = int(value * 127. / self.scale + .5) + self.i2c.i2c_write([val]) + +def load_config_prefix(config): + return mcp4018(config) |