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mcp4728: Update to better match printrbot revf requirements 

Reported by @Grumps49.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2019-07-26 10:59:07 -04:00
parent 73709984b0
commit a878831d5e
3 changed files with 15 additions and 10 deletions
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17
config/example-extras.cfg
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@ -890,27 +890,28 @@
#i2c_mcu: mcu
# The name of the micro-controller that the MCP4451 chip is
# connected to. The default is "mcu".
#i2c_address:
#i2c_address: 96
# The i2c address that the chip is using on the i2c bus. The default
# is zero.
# is 96.
#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.
# highest voltage (2.048V) 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.
# its highest voltage (2.048V), 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.
# Statically configured MCP4018 digipot connected via two gpio "bit

4
docs/Config_Changes.md
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@ -6,6 +6,10 @@ All dates in this document are approximate.
# Changes
20190726: The mcp4728 digital-to-analog code has changed. The default
i2c_address is now 0x60 and the voltage reference is now relative to
the mcp4728's internal 2.048 volt reference.
20190710: The z_hop option was removed from the [firmware_retract]
config section. The z_hop support was incomplete and could cause
incorrect behavior with several common slicers.

4
klippy/extras/mcp4728.py
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@ -7,7 +7,7 @@ import bus
class mcp4728:
def __init__(self, config):
self.i2c = bus.MCU_I2C_from_config(config, default_addr=0)
self.i2c = bus.MCU_I2C_from_config(config, default_addr=0x60)
scale = config.getfloat('scale', 1., above=0.)
# Configure registers
for i, name in enumerate('abcd'):
@ -17,7 +17,7 @@ class mcp4728:
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])
((value >> 8) & 0x0f) | 0x80, value & 0xff])
def load_config_prefix(config):
return mcp4728(config)