diff options
| -rw-r--r-- | config/example-extras.cfg | 30 | ||||
| -rw-r--r-- | config/generic-printrboard.cfg | 8 | ||||
| -rw-r--r-- | klippy/extras/mcp4728.py | 23 |
3 files changed, 61 insertions, 0 deletions
diff --git a/config/example-extras.cfg b/config/example-extras.cfg index 0afc5ae3..a0223c4f 100644 --- a/config/example-extras.cfg +++ b/config/example-extras.cfg @@ -639,6 +639,36 @@ # to not scale the 'wiper_x' parameters. +# Statically configured MCP4728 digital-to-analog converter connected +# via I2C bus (one may define any number of sections with an "mcp4728" +# prefix). +#[mcp4728 my_dac] +#i2c_mcu: mcu +# The name of the micro-controller that the MCP4451 chip is +# connected to. The default is "mcu". +#i2c_address: +# The i2c address that the chip is using on the i2c bus. The default +# is zero. +#channel_a: +#channel_b: +#channel_c: +#channel_d: +# The value to statically set the given MCP4728 channel to. This is +# typically set to a number between 0.0 and 1.0 with 1.0 being the +# highest voltage and 0.0 being the lowest voltage. However, the +# range may be changed with the 'scale' parameter (see below). If a +# channel is not specified then it is left unconfigured. +#scale: +# This parameter can be used to alter how the 'channel_x' parameters +# are interpreted. If provided, then the 'channel_x' parameters +# should be between 0.0 and 'scale'. This may be useful when the +# MCP4728 is used to set stepper voltage references. The 'scale' can +# be set to the equivalent stepper amperage if the MCP4728 were at +# its highest voltage, and then the 'channel_x' parameters can be +# specified using the desired amperage value for the stepper. The +# default is to not scale the 'channel_x' parameters. + + # 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/config/generic-printrboard.cfg b/config/generic-printrboard.cfg index 8a667370..04db045a 100644 --- a/config/generic-printrboard.cfg +++ b/config/generic-printrboard.cfg @@ -74,3 +74,11 @@ max_velocity: 300 max_accel: 3000 max_z_velocity: 5 max_z_accel: 100 + +# Use the following on a Printrboard RevF to control stepper current. +#[mcp4728 stepper_current_dac] +#scale: 2.327 +#channel_a: 1.3 # Extruder +#channel_b: 1.1 # stepper_z +#channel_c: 1.1 # stepper_y +#channel_d: 1.1 # stepper_x diff --git a/klippy/extras/mcp4728.py b/klippy/extras/mcp4728.py new file mode 100644 index 00000000..6f2eeb29 --- /dev/null +++ b/klippy/extras/mcp4728.py @@ -0,0 +1,23 @@ +# MCP4728 dac code +# +# Copyright (C) 2018 Kevin O'Connor <kevin@koconnor.net> +# +# This file may be distributed under the terms of the GNU GPLv3 license. +import bus + +class mcp4728: + def __init__(self, config): + self.i2c = bus.MCU_I2C_from_config(config, default_addr=0) + scale = config.getfloat('scale', 1., above=0.) + # Configure registers + for i, name in enumerate('abcd'): + val = config.getfloat('channel_%s' % (name,), None, + minval=0., maxval=scale) + if val is not None: + self.set_dac(i, int(val * 4095. / scale + .5)) + def set_dac(self, dac, value): + self.i2c.i2c_write([0x40 | (dac << 1), + (value >> 8) & 0x0f, value & 0xff]) + +def load_config_prefix(config): + return mcp4728(config) |