2012-06-01T15:07:06Z

Bubbapizza: /* Replication */

=Infrastructure=

Our telecommunication infrastructure consists of:

*1 coaxial cable connected to the hardware of our Internet Service Provider (ISP)

*1 DSL filter

*1 6P6C phone cable (3ft each)

*1 modem

*3 WRT54GL routers ([http://www.amazon.com/Cisco-Linksys-WRT54GL-Wireless-G-Broadband-Router/dp/B000BTL0OA Source])

*1 indoor Cat5e cable (3ft each)

*2 outdoor waterproof direct burial Cat5e cables (200ft each) ([http://www.amazon.com/Outdoor-Waterproof-Ethernet-Direct-Burial/dp/B001B6FY4O/ref=sr_1_1?ie=UTF8&qid=1338504293&sr=8-1 Source])

=Hardware Setup=

*The ISP's coaxial cable connects to the DSL filter.

*The DSL filter connects via 6P6C phone cable to the modem's DSL port.

*1 of the modem's Uplink ports connects via indoor 3ft Cat5e cable to the Internet port of the wireless router (Base Router).

*1 of the base router's LAN ports connects via outdoor 200ft Cat5e cable to 1 of the LAN ports of another wireless router (Primary Boost Router).

*1 of the primary boost router's LAN ports connects via outdoor 200ft Cat5e cable to 1 of the LAN ports of another wireless router (Secondary Boost Router).

=Software Setup=

*Router firmware: [http://www.polarcloud.com/tomato Tomato]

*Base router's settings:

'''Basic'''

Network: PPPoE

DHCP Server: Enabled; 192.168.1.100 to 192.168.1.199

Router IP Address: 192.168.1.1

Subnet Mask: 255.255.255.0

*Boost routers' settings:

'''Basic'''

Network: Disabled

DHCP Server: Disabled

Router IP Address: 192.168.1.3 (second router); 192.168.1.4 (third router)

Subnet Mask: 255.255.255.0

=Replication=

*'''How to Connect 2 Routers with an Ethernet Cable:''' (thanks to [http://homecommunity.cisco.com/t5/Wireless-Routers/Connecting-two-routers-wired-the-definitive-answer/td-p/47006 Cisco Forums])

Assume you have 2 routers, the first already connected to the internet.

1. Power on the second router without anything connected to its ports. Connect a single computer to the router. Do not connect the second router to the first at the moment!

2. Configure the router at http://192.168.1.1/

3. Change the LAN IP address of the second router from 192.168.1.1 to a free address in your LAN (e.g. 192.168.1.2 should be O.K. if the first router is also a Linksys router). The address you change to (192.168.1.2) must not be used by any other device with static IP address in your network nor should be assigned by the DHCP server your network. A default Linksys router uses 192.168.1.1 itself and the DHCP server assigns 192.168.1.100-149.

4. Turn off the DHCP server on the second router.

5. Save the setting.

6. Unplug the computer from the second router.

7. Connect an ethernet cable from a numbered LAN port of the first router to a numbered LAN port of the second router. Do not use the Internet/WAN port on the second router!

8. That's it! If you don't know or don't want to know more about networking you don't have to read the rest here.

'''What do you have now?'''

The second router is connected through a LAN port to your existing network. This basically means that the router part of the device is actually not used. So you have a router device that you don't operate as router in your network. Whatever you connect to the second router either through one of the remaining LAN ports or through a wireless if it has one, is directly connected to your LAN. Devices connected to the second router use the DHCP server of the first router to get an IP address. They use the first router directly for internet access. Everything is connected to a single larger ethernet network. Everything is in a single "broadcast" domain. This is called [[Wikipedia:Bridging (networking)|bridging]].

If the second router is not a wireless one, you basically have a few more ports in your network. In that case it might have been cheaper to get a simple switch/hub instead to extend your network.

Please remember: as the second router is not connected through the Internet/WAN port many configurations and functions of the second router won't work simply because they require an internet connection on the router itself. Some examples are: access restrictions, dynamic DNS service, port forwardings, MAC address clone, the firewall... All these things must be configured on the first router and only there.

'''Why is this better than connecting the second router with the Internet port?'''

If you have a second router connected via the Internet port...

A router is a separating network element. It separates two networks and allows certain traffic to cross. Sometimes this is necessary in a network setup but for most home networks it only creates a lot of obstacles.

1. In default Gateway mode the second router does network address translation (NAT). This means computers connected to the second router can connect to computers connected to the first router but not in the opposite direction.

2. If you use Router mode on the second router: you have to configure "routes" on the first router and possibly your computer connected to the first router so that IP packets find their way into the subnet of the second router.

3. You have two separate ethernet networks and thus two "broadcast" domains. A broadcast in the first router's subnet reaches all computers connected there. The same applies to the second router. A broadcast will never cross the second router, though. This is an obstacle for applications that depend on broadcasting to locate other computers and services. Windows file and printer sharing is one example here. With the second router in between, computers on one side do not know about computers on the other side. You cannot search your workgroup for the computer on the other side even when they use the identical workgroup name. You will be able to access the other computer using the IP address directly (e.g. \\192.168.1.100\share) but that's usually a hassle and the IP address may change if it is assigned by the DHCP server to the computer. There are ways to deal with some of these issues (e.g. save the host names in lmhosts files...) but all this requires more effort and attention to keep everything up-to-date.

4. Port forwardings become more complicated. If you need a port forwarding (i.e. you want a port on a computer in your network to be accessible from the internet) on a computer connected to the second router you have to setup two forwardings: one on the first router to the second router and one on the second router to the computer.

5. If you have two wireless routers: you cannot roam between both routers without loosing the connection. This is simply because if a wireless computers moves from one router to the other it needs a different IP address.

6. The whole configuration becomes more complicated: you always have to think about where to configure what, e.g. dynamic DNS service, access restrictions, ...

Bottom line: unless you have good reasons why you must have some computers separated from the other computers in your network, there is no good reason to in a home network to do so. For normal home networking with simple to use file and printer sharing it is better to connect the second router as suggested in this post...

Open Source Stepper Motor Controller

2012-05-31T01:02:00Z

Bubbapizza: /* References */

{{Category=RepLab Tools}}

'' See also [[Stepper Motor]]'' and see also [[Problem_Statement_for_a_Universal_Power_Supply]]

=Factor e Farm Status=
[[SnapLock CNC]] and [[Open Source Torch Table Prototype II]] are being built in January 2012.
=Introduction=

See [[Open Source Stepper Motor Controller Problem Statement]] as a start.

Stepper motors are the simplest drive for moderate precision motion control applications (such as CNC plasma cutting). They provide the best price:performace for low to moderate mechanical power (<200W) at low to moderate RPM (<500 RPM). There is no open source stepper driver, AFAIK. This project will fill that need.

=Concept=

The output of this project will be a family of general purpose electronic drivers for a variety of electromechanical actuators. The first of them will be a stepper motor driver. With the appropriate alternative firmware (embedded software) the same hardware might be used as a servo driver for a brush-DC servo. With a modified output stage we could drive brushless DC or AC servos, or linear motors.

=Design Rationale=

Adaptability is good. Software is usually easier than hardware. Microprocessors are cheap. Simple circuits are better than complicated ones (other things being equal).

We keep the circuit simple and general, and we implement the control algorithm in software. We can tweak it most easily that way, and even replace it with something totally different.

This design should give good performance, excellent versatility, good replicability, and moderate cost.

=Block Diagram and Modules=

Major functional units:
* Computational logic. An Arduino could be used in the initial prototype, for speed of development. Later versions would want a cost reduced and/or higher performance microprocessor, or an FPGA for minimum latency and maximum bandwidth. The logic must be shielded from electromagnetic interference by the other parts of the system, especially the output drive (and the plasma cutter, if there is one). Independent power and small signal power supplies, and careful grounding, are likely to be needed.
* Fast A/D converters. Allows the logic to monitor the current flowing through the load.
* High power robust drive circuit. N-channel power MOSFETs in an H bridge, with appropriate protection. Select MOSFETs with plenty of current and voltage headroom, and favour ones with built in clamp diodes. A stepper motor is a heavily inductive load, so it can generate voltages substantially outside the supply rails.

[[File:Stepper-drive-block-diagram.jpg|200px|Stepper drive block diagram.]]

[[File:Stepper-drive-H-bridge.jpg|200px|Stepper drive H-bridge.]]

An H-bridge allows the voltage to be applied to the load (to motor winding) in either direction.

[[File:Stepper-drive-schematic-symbols.jpg|200px|Stepper drive schematic symbols.]]

[[File:Stepper-drive-normal-operation.jpg|200px|Stepper drive normal operation.]]

Top row: active current path. Bottom row: Corresponding Current (I) and Voltage (V) graphed against time.

From left to right: Positive applied voltage, rapidly increasing current; No voltage (except due to the resistance of the wires, gradually decreasing current; Negative applied voltage, rapidly falling current.

[[File:Stepper-drive-failure-modes.jpg|200px|Stepper drive failure modes.]]

Shoot-through occurs when both transistors on one side of the H are turned on at the same time. It shorts the rails together and blows the transistors in a few us.

The overvoltage shown occurs when all the transistors are turned off simultaneously while current is flowing. Stopping the current near instantly creates a huge voltage spike. The same effect can occur if a motor lead comes loose while the driver is operating.

[[File:Stepper-drive-waveforms.jpg|200px|Stepper drive waveforms.]]

Contrast stepping with microstepping. The microstepping gives less vibration and smoother movement, and makes it possible to stop between the steps.

[[File:Stepper-drive-MOSFET-timing.jpg|200px|Stepper drive MOSFET timing.]]

MOSFETS take some time to turn on and off. We need to take account of this for optimum performance (or even for to avoid the above failure modes?). See the MOSFET data sheet for exact timings.

=== Method of operation: ===

*Position instructions come to the drive from EMC. These could be step and direction pulses or some more structured data.
*The drive determines target current for each winding.
*The drive uses software [http://en.wikipedia.org/wiki/PID_controller PID] compensation to achieve and maintain those drive currents.
** sensor: voltage induced across sense resistor by the drive current.
** actuator: [http://en.wikipedia.org/wiki/Pulse-width_modulation PWM] of applied voltage between the three normal operation modes.
*The drive determines new target current for next (micro-)step.

=Prior Art=

This design offers a higher power version (up to 75 amps) of a stepper motor controller, and addresses the feedback loop:

http://www.piclist.com/techref/io/stepper/hipwrbp-gm.htm

[[Image:steppermotorcontroller.gif]]

==Comment by Chris Palmer==
That is only part of a driver circuit. The current sense circuit is not shown and it looks like the firmware will have to do the sequencing, current control and microstepping. The LM5101 is not recommended for new designs.

There are more modern chips that you just add external FETs and sense resistors to get a complete microstepping chopper driver. For example: http://www.allegromicro.com/en/Products/Part_Numbers/3986/index.asp

=References=
*RepRap wiki - good references on stepper controllers - [http://reprap.org/wiki/StepperMotor]
*[http://en.wikipedia.org/wiki/Stepper_motor Stepper Motor in Wikipedia]
*[http://www.cs.uiowa.edu/~jones/step/index.html An excellent discussion of concepts]
*Control of DC motors explained - [http://www.tigoe.net/pcomp/code/circuits/motors/controlling-dc-motors]
*Sample stepper motor controlled with Arduino using EasyDriver - [http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=pt&tl=en&u=http%3A%2F%2Flusorobotica.com%2Findex.php%2Ftopic%2C106.0.html&act=url]
*Dr. Iguana's open source stepper motor based on a pic microcontroller : http://www.dr-iguana.com/prj_StepperDriver/

=Research=
*[http://www.google.com/search?client=ubuntu&channel=fs&q=stepper+motor&ie=utf-8&oe=utf-8 Google: stepper motor]
*[http://www.google.com/search?client=ubuntu&channel=fs&q=stepper+controller+integrated+circuit&ie=utf-8&oe=utf-8 Google: stepper controller integrated circuit]
*[http://www.google.com/search?client=ubuntu&channel=fs&q=stepper+controller+chip&ie=utf-8&oe=utf-8 Google: stepper controller chip]
*[http://www.google.com/search?client=ubuntu&channel=fs&q=NEMA+34+stepper+motors&ie=utf-8&oe=utf-8 Google: NEMA 34 stepper motors]

=Development Team=

*[[Leo.dearden]] - Ideas. I'm too busy to do very much at the moment, but I'll do what I can.
*[[Yoonseo Kang]]
*[[Darren Vandervort]]
*[[Stefan Ludwig]]

=See Also=
* [[Stepper Motor]]
* [[Open Source Stepper Motor]]

[[Category:Torch Table]]

CNC Circuit Mill

2012-02-27T16:18:27Z

Bubbapizza: /* Iterations */

=Introduction=

*'''Example of CNC Circuit Milling on a Commercial CNC Circuit Mill'''

<html>

<iframe width="320" height="247" src="https://www.youtube.com/embed//oEQsAi_eRAI" frameborder="0" allowfullscreen></iframe>

</html>

*As you can see, the milling bit rotates at very high speeds (thousands of complete rotations per minute, aka "revolutions per minute" or just "rpm") and removes material from the top layer (and a bit of the bottom layer) of the circuit board.

*The circuit board is comprised of a thin top layer of conductive material (often copper) that is adhered to a layer of insulating material below.

*During milling, the insulating layer provides a safety gap between the milling bit and the precision work surface (which should not be marred).

*Once the milling is complete, the remaining copper traces form the actual conductive circuit (without the components soldered yet), while the relatively intact insulating layer gives the circuit board its rigidity.

=Industry Standards=

*'''LPKF'''

http://www.lpkfusa.com/downloads/support/docs/man_c40.pdf

*'''Tormach: PCNC 1100 Series 3 CNC Mill'''

http://www.tormach.com/Product_PCNC_main2.html?gclid=CNqspeb8r64CFUcCQAodmBSZRw

http://www.tormach.com/uploads/300/TD_Series_3_Whitepaper_v4-0-pdf.html

Ballscrews and nuts, hybrid polyphase stepper motors, microstepping digital electronics

=Iterations=

*'''Version In Progress'''
[[CNCCMV2]]

*'''Version 1'''

[[CNCCMV1]]

==See Also==
*[[CNC Circuit Mill Discussion]]
*[[CNC Circuit Mill Concept]]
*[[Stepper Motor]]
*[http://blog.ponoko.com/2011/07/15/pricing-guide-to-diy-cnc-mill-and-router-kits/ Comparison of CNC kits]
*[[Mantis 9]]
*[[Snaplock]]
*[[Shapeoko]]

*[http://en.wikipedia.org/wiki/Printed_circuit_board_milling Wikipedia: Printed Circuit Board Milling]

[[Category:Circuit Board Fabrication]]

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