I accept the core premise of reprap. I accept that many people will not want to build circuit boards. I simply believe that the platform should be built with extensibility in mind. I think one very important extension is electronics manufacturing. That's it. That's all there is to it.by Annirak - Controllers
aka47, I think there's a growing number of us on the same page. I'm not sure that headswap goes well with X/Y monitoring. I'm beginning to wonder if CAN might be more suitable than RS485 given the complexity we're starting to create.by Annirak - Controllers
Viktor, That sounds like a great solution! Have you posted details anywhere?by Annirak - General
grael, The STM32F103VBT looks nice... except for the price. I've been looking at the LPC23xx for similar jobs and they are FAR cheaper, though their ADC's aren't as nice. But they DO include ethernet. Brendanby Annirak - Controllers
grael, I think we come from similar backgrounds. I completely agree with your move to ARM. I'm sticking with ATMega for now out of respect for those who don't have PCB manufacturing capabilities (including me!) I'm designing a modular control system which, I understand, you don't like. I agree with you on cost, but I do have a few technical reasons for going the route I am. My system has oneby Annirak - Controllers
Hi Graham, Maybe we should work together on this. I'll check out your thread and see where it's going. Brendanby Annirak - Controllers
jbb, I figured that the load would be enough to keep the PSU in regulation, but if that's going to be a problem then I will put in a regulator. You're absolutely right about the FETs. The ones I have are for >100kHz switchers, so you know they're low gate charge . Good catch on the flyback diodes... Oops. Nice idea on the decoder, but here's an even better part: 74hc154 Know of any good hby Annirak - Controllers
Firstly, I cannot fathom a place where it's feasible to get a PC, all the electronics to run a reprap, stepper motors, and not a webcam. Honestly, they cost $23 CAD for a 1.3MP (interpolated) camera ( ). The reprap steppers sells for $30 CAD. Secondly, the point always was for calibrating the x/y-axis position of a swappable toolhead. The problem is that two extruder nozzles may not hold theby Annirak - General
Here are the initial schematics for my toolhead controller. It's not ready to go to PCB yet. Consider this a request for comments. Caveats: 1) Some of the bulk storage and decoupling caps are missing. That's purely because I missed them when I was exporting the schematics. 2) I see now that I've missed the I2C pullups. 3) No resistors have values set yet, and the MOSFET's are missing model nby Annirak - Controllers
After spending some time looking at cartesian bot options, I've decided a couple of things. I want to keep a high maximum acceleration in the bot, which means that I'll need to keep the mass it moves down. To that end, the only thing I want to move is the toolhead. This rules out gantry robots. For toolhead-only cartesian robots, there are two options that I can see: 1) The reprap style whichby Annirak - Mechanics
GeertB Wrote: ------------------------------------------------------- > Seems this is some > beefy stepper, That's the idea > which will require some expensive > electronics to drive. I've spent time doing power supply design. I'll design a controller for it.by Annirak - Mechanics
The rated holding voltage is 1.8V, so it's really not that bad.by Annirak - Mechanics
Ok, so the steppers I have are unipolar NEMA 34 steppers. They draw 4.8A/phase. I'm looking for the best option for using these to build the basis of my cartesian bot.by Annirak - Mechanics
jbb, I agree that a shared sync line could cause problems. My solution is a little simpler: Just run the RS-485 at 1Mbps (most transceivers go up to 5Mbps). You'll get very little jitter then. RS-485 is designed for industrial environments with precisely this problem in mind. Because it is a differential signal, the majority of electrical noise is dropped because it is common to both halvesby Annirak - Controllers
While I was looking through my parts bin last night, I came across two really big steppers that I've had kicking around for a while. They about a 3/8" shaft, come with toothed pulleys and weigh something like 5 lb each. I'll update with specs tonight when I have them in front of me. I'm trying to work out what kind of cartesian bot to build. I have a lot of torque to move things really quicklby Annirak - Mechanics
As of this morning, I have everything except the Docked signal and I2C laid out in schematics. I'll be trying to do the PCB in single layer to facilitate hobby prototyping methods. We'll see how that goes.by Annirak - Controllers
My design is one controller per toolhead. It always has been. The I/O are 6 (spi + 2 SS for MAX6675 + 1 spare slave select) 2 (I2C) 6 (2xPWM + 4 quadrature or endstop) 8 (2xMotor + 4 quadrature) 3 (RS485 TX/RX/TXEN) 4 (ADC) 1 (Docked) ----- 30 As of yet, the remaining two I/O pins are reserved for the second serial port as a debug port. I expect that to change as I develop the code. Incidenby Annirak - Controllers
I'm beginning to think that the 28-pin AVR's aren't going to have enough I/O. For the featureset that I've described, we've got a lot of pins: 6 (spi) 2 (I2C) 2 (PWM) 2 (Motor) 4 (RS485) 2 (ADC) 2 (Quadrature) 1 (Docked) ----- 21 For devices limited to 23 I/O pins, we're already pretty close to the limit, where features start overlapping with no option for dock ID's and extra GPIO. Particularby Annirak - Controllers
Wade Wrote: ------------------------------------------------------- > There might be a way to hack the drivers to make > USB do RS232 without an adapter, but I haven't > heard of one yet. Doesn't mean it doesn't exist > or can't be done. Not sure it's worth the > effort though. There isn't a way to do it. The physical layer of the USB port is much closer to RS-485 than it iby Annirak - Controllers
A few points: I was planning on doing full duplex RS-485 so that the main controller never has to wait for a toolhead processor to release the bus. The having multiple SPI headers is so that multiple sensors can be attached. It's one extra GPIO pin to add a second header, so why not? I don't know if we need a dock ID. It just made sense to me that the toolhead processor be able to tell whiby Annirak - Controllers
Mr. Seeker Wrote: ------------------------------------------------------- > Check here: > > > Ideas > > Maybe you can find some more? I think I actually covered more options than there are on that page, though with much more general terms.by Annirak - Controllers
I'm building a toolhead controller for my extruder experiments so that I have a common platform for controlling all aspects of the toolhead. There are a few advantages to this, such as controlling all the toolheads in a standard manner. I'm trying to decide on the featureset. I'd like input on what features will keep this design extensible without major revisions. After playing around with aby Annirak - Controllers
While you may dislike Java, and I dislike Java, there's two points to recommend it over python: 1) Python's class handling sucks. I mean it's downright terrible. I say this despite the fact that I love working with python and I think it's marvelous. But oo code in python is really annoying. self.anything_in_your_class is really annoying to write. You'd think they'd have left that distinctionby Annirak - RepRap Host
use the attach a file linkby Annirak - Controllers
Updated the builder's blog with new info regarding this project.by Annirak - Controllers
With the discussion of making electronics, be it SMD or printing circuits, and other forms of fabbing where we introduce parts that are not fabbed all in one run (e.g. building captive nuts) it seems that we need to spend a little time thinking about how to detect positions and how to calibrate the location of a reprap's extrusion. This, naturally, brings up the question of machine vision. Peopby Annirak - General
I've been thinking about this one for a while too. Reverse-building boards has a lot to recommend it. Including not worrying about pick & place. The only concern I have is alignment. With fine pitch parts, it could be pretty bad to be off by 0.5mm. We need ridiculous accuracy or machine vision to make this work. I'll be experimenting with conductive plastic pretty soon (just waiting fby Annirak - RepLab Working Group
Thanks, nophead. That's all I needed to know. I'll let that one drop and focus on something more useful to occupy myself.by Annirak - Controllers
I spent some time last night thinking about quadrature decoding. I worked out a circuit which does it using two D flipflops, 3 XOR gates, two Schmitt trigger NOR's, and a quad two-input multiplexer. This gives a clock pulse on every transition, using different pins for up pulses and down pulses. Is this something which is useful for RepRap? The part count (5 ICs)is a little ridiculous, whicby Annirak - Controllers
Looks like thrust bearings can be had for <$10 from ebay.by Annirak - Mechanics