LAOS Laser

h1. LAOS configuration file

The LAOS Mainboard looks for a "config.txt" file on the MBED, to obtain some essential settings on power-up. It can be set up and modified my plugging the MBED into USB, which will cause it to appear as a USB drive with that config.txt file on it. 

The proper settings will depend on your configuration, attached is a file which works with the [[HPC LS3020]], [[LAOS mainboard v0.3]], and the July 7th release of the [[LAOS firmware]].

h3. Location

The configuration file is located on the MBED USB partition and is named *config.txt*. When a *config.txt* file is found  on your SD card, this will take precedence over the file on the MBED.

h3. Sample configurations

Sample configuration files can be found at the end of this page. Copy it and edit it to match your needs. If you configure LAOS for a new machine, please add your configuration file to this page.

h3. Updating the configuration file

You can update the file by connecting the MBED to a PC with the USB connector. It should be visible as a small (2Mbyte) USB disk (label: MBED). Copy the configuration file to the root of this disk and eject the disk, using the appropriate method for your operating system (unmount, eject, save remove, etc.). You need to reset the laser to read the new configuration file. Use the reset button on the MBED or power down the system (make sure you remove the USB cable, or the MBED will not power down).

h3. Format

The general format is:

<pre>

name value

</pre>

Each value is a single word, without spaces.

h4. Comments

Comments can be included with a semicolon (";") character. All characters after the semicolon (up to a newline) are

ignored. Multiple Whitespace and newlines are ignored. 

h4. Sections

The file contains various sections that configure different parts of the system.

The exact location of these sections (and ordering of their parameters) is not significant. Each parameter has a default value that

is used if the parameter is not found in the configuration file, so they can be omitted if the defaults suit you. It is advised to

include all parameters in the file, because the defaults may change in the future, causing your system to fail when you update the 

firmware.

h4. Network

The network parameters define the network configuration. The minimal network configuration is '''net.dhcp 1'''. In this case, the laser will request a IP address from a DHCP server in the network, and is accessible via port 2000. You may need to instruct your DHCP server to hand out a fixed IP address, or assign a DNS entry to the laser, otherwise it may be difficult to 'find' the laser in the network.

<pre>

net.dhcp 0                    ; Enable DHCP for IP address [0/1], if enabled, the other network settings (except port number) are not used

net.port 2000                 ; Communication socket port number []

net.ip 192.168.0.111          ; IP address [xxx.xxx.xxx.xxx] 

net.netmask 255.255.255.0     ; netmask [xxx.xxx.xxx.xxx] 

net.gateway 192.168.0.1       ; gateway

net.dns 192.168.0.1           ; DNS server

net.port 69                   ; Port the TFTP server is available on

</pre>

h4. System

This section defines the behavior of the system.

<pre>

sys.autohome 0                ; Enable automatic homing at startup [1/0] or wait for cover to close (you need a cover sensor)

sys.autozhome 0               ; Enable automatic homing of Z axis at startup [1/0] or wait for cover to close (you need a cover sensor)

sys.nodisplay 0               ; Disable the I2C display [1/0]

sys.i2cbaud 100000            ; I2C display baudrate [Hz]

sys.cleandir 1                ; Clean out directory on startup

</pre>

Note: Enabling the display, while no display is connected can lead to continuous reboots of the firmware during startup. It is than difficult to change back this setting. 

Hold the button on the mbed and keep it pressed while inserting the MBED USB connection. Now update the config file.

h4. Laser

The properties of the laser are described here.  To invert the laser polarity, switch round the values in laser.pwm.min and laser.pwm.max

<pre>

laser.enable 0                ; Laser enable signal polarity [0/1]

laser.on 1                    ; Laser on signal polarity [0/1]

laser.pwm.min 0               ; minimum pwm value [%]

laser.pwm.max 100             ; maximum pwm value [%]

laser.pwm.freq 20000          ; pwm frequency [Hz]

</pre>

h4. Motion

The motion section defines the overall motion properties. 

<pre>

motion.enable  0              ; Enable signal state to enable motors [0/1] 

motion.homespeed 100          ; Homing speed [microsecond/step]

motion.speed  400             ; max linear speed [millimeter/sec]

motion.accel  1000            ; linear acceleration [millimeter/sec2]

motion.tolerance  50          ; tolerance for cornering [micrometer] (larger is faster, but less accurate corners) 

</pre>

Note: the homepseed is specified as microseconds/step: a LOWER value means FASTER homing. Depending on your microstep resolution, values from 50 to 5000 are typical.

The motion.speed is the speed that corresponds to 100% speed setting in your drawing.

h4. Axis

The various axis are configured with their respective values. An axis definition may exist for up to four axis (x,y,z,e).

At least two should be configured (x and y).

<pre>

; Next values are valid for axis x,y,z and e

x.pol 0                       ; home/limit sensor polarity [1/0]. Inverts the input of the switch, so it can be a N.O. or N.C. switch.

x.homedir 0                   ; state of the direction signal when homing (axis should move towards home-sensor) [1/0]

x.home 320000                 ; home positions [micrometer], this is the position we assume the home switch to be located 

x.scale -136986               ; axis scaling [steps/meter], use negative number to invert direction signal 

x.invert  1                   ; Invert signal polarity for step signal [1/0]

x.min 0                       ; minimal position [micrometer]. The axis is not allowed to move beyond this position 

x.max 320000                  ; maximum position [micrometer]. The axis is not allowed to move beyond this position 

x.rest 310000                 ; rest position [micrometer]. The position the axis assumes before/after a job

x.speed 1000                  ; maximum speed [millimeter/sec]. The maximum speed this axis is allowed to move at

</pre>

Note: Currently the min/max and speed setting are not used. They can be left at the default value. During homing the axis is moved at a constant speed (as defined in the

system configuration) and jogging via the LCD is done at a fixed speed.

The procedure to configure this section correctly: 

# Make sure the axis home in the correct direction (towards the home switch) using pol and homedir 

# Set the coordinate of the home position in the home setting (in micrometers)

# Set the number of steps per meter in the scale parameter (use negative number to flip the positive axis direction)

# The rest position if configured with a position to move the axis out of the way after a job (so you can remove the workpiece)

Watch out when using VisiCut, in the device xml of a lasercutter there are options to flip the axis (flipXaxis and flipYaxis). It's probably best to set both to false. (Or set them so that the x and y's home and rest distances make sense.