Announcing the ORDuino !
Posted: Thu Mar 01, 2012 5:54 pm
As i know a lot of people here are ordering or about to their Orduino's + RAMPS + Pololu's etc. for the ORDbots,
I thought i should tell you about what i'm doing on this front now even if its a little early -
I dont have any board rederings yet, but the schematics are done and i'm half-way through the board layout already.
The board will be about 160mm x 60mm - it may change a little along the way, but thats pretty stable now.
i might grow it to 80mm wide if it saves time for the prototype layout but then the production version will be smaller.
Here are the basic features :
100% surface mount or as much as possible to keep the assembly costs down;
- this also allows the board to be bolted flat against makerslide or aluminum plate and use that as a *very* efficient heatsink
- Arduino Mega / RAMPS software- compatible, but no Arduino stacking headers
- Micro-SD card socket
- FTDI-based USB interface like previous arduinos for easier programming.
- RS-485 serial interface
- Local switching 5V regulator can take 24V in;
- up to 5 stepper axes @ 30V 3A max.
- also has connector header footprints for Pololu/stepstick a3988 drivers, in case you accidentally blow up one of the on-board drivers
(it is designed so you can easily use an exacto to isolate a blown driver and install and new driver board over it )
- Robust design with protection features, so its very unlikely the above scenario will happen in practice, unless one is extremely careless.
- All motor outputs connect with 3.5mm pitch pluggable terminal blocks; these also include connection for limit switches for that axis:
one terminal block per axis.
- 3 high current transistor outputs; Transistors are SMT and are rated 50A max, designed in system to easily handle 20-30A @ 24V.
- extra protection features here too, and current & temperature monitoring in software as well.
- 5mm pluggable terminal blocks on Power input and Heater outputs.
- FFC connector to directly drive the heated build plate that way, if you prefer.
- Buzzer for alarm / "done" signal.
- 4 "R/C style" servo headers
- 3/4 thermistor inputs (3.5mm pluggable terminal blocks )
Some options i may add before i'm done if you tell me it would be useful:
- Thermocouple interface?
- LCD interface ? ( i have a lot of new old stock of 128x64 monochrome LCD, about credit card size)
- ATX supply connector, or other connectors for common power supplies: Barrel jack, 6-pin mini-fit, or DIN.
- Joystick or other user control interface ?
I was trying to add SMT-style 1/4" faston tabs for power & heaters as well but that probably wont happen because they take so much space.
Its hard to find low cost, compact pluggable connectors that can handle 20-40A for the power and heater connections- especially surface-mount ones. It also requires special consideration in the board layout. As it is this board will probably use 2 or 3oz copper; a bit more expensive but at least it helps with heatsinking. If you agree the 1/4" Faston tabs are a good compromise, i will add these, though making the board 80mm wide rather than 60mm. The alternative power connectors are through-hole only so standoffs will be needed to mount it, and possibly a heat-sink in more demanding applications, although the board is designed to run cool when driving an ORDbot, so heatsink should be unnecessary.
What do you think so far?
PS my target price for all this is $130 for 4 axes / 2 heaters and $150 for an "all dressed" 5 axis 3 heater version.
Possibly less if i get enough interest / reservations.
I'm hoping to finalize the design by the end of the coming weekend so i can order prototypes along with the Heated build plates, so please dont be shy to give me your opinion and suggestions right away!
Cheers
I thought i should tell you about what i'm doing on this front now even if its a little early -
I dont have any board rederings yet, but the schematics are done and i'm half-way through the board layout already.
The board will be about 160mm x 60mm - it may change a little along the way, but thats pretty stable now.
i might grow it to 80mm wide if it saves time for the prototype layout but then the production version will be smaller.
Here are the basic features :
100% surface mount or as much as possible to keep the assembly costs down;
- this also allows the board to be bolted flat against makerslide or aluminum plate and use that as a *very* efficient heatsink
- Arduino Mega / RAMPS software- compatible, but no Arduino stacking headers
- Micro-SD card socket
- FTDI-based USB interface like previous arduinos for easier programming.
- RS-485 serial interface
- Local switching 5V regulator can take 24V in;
- up to 5 stepper axes @ 30V 3A max.
- also has connector header footprints for Pololu/stepstick a3988 drivers, in case you accidentally blow up one of the on-board drivers
(it is designed so you can easily use an exacto to isolate a blown driver and install and new driver board over it )
- Robust design with protection features, so its very unlikely the above scenario will happen in practice, unless one is extremely careless.
- All motor outputs connect with 3.5mm pitch pluggable terminal blocks; these also include connection for limit switches for that axis:
one terminal block per axis.
- 3 high current transistor outputs; Transistors are SMT and are rated 50A max, designed in system to easily handle 20-30A @ 24V.
- extra protection features here too, and current & temperature monitoring in software as well.
- 5mm pluggable terminal blocks on Power input and Heater outputs.
- FFC connector to directly drive the heated build plate that way, if you prefer.
- Buzzer for alarm / "done" signal.
- 4 "R/C style" servo headers
- 3/4 thermistor inputs (3.5mm pluggable terminal blocks )
Some options i may add before i'm done if you tell me it would be useful:
- Thermocouple interface?
- LCD interface ? ( i have a lot of new old stock of 128x64 monochrome LCD, about credit card size)
- ATX supply connector, or other connectors for common power supplies: Barrel jack, 6-pin mini-fit, or DIN.
- Joystick or other user control interface ?
I was trying to add SMT-style 1/4" faston tabs for power & heaters as well but that probably wont happen because they take so much space.
Its hard to find low cost, compact pluggable connectors that can handle 20-40A for the power and heater connections- especially surface-mount ones. It also requires special consideration in the board layout. As it is this board will probably use 2 or 3oz copper; a bit more expensive but at least it helps with heatsinking. If you agree the 1/4" Faston tabs are a good compromise, i will add these, though making the board 80mm wide rather than 60mm. The alternative power connectors are through-hole only so standoffs will be needed to mount it, and possibly a heat-sink in more demanding applications, although the board is designed to run cool when driving an ORDbot, so heatsink should be unnecessary.
What do you think so far?
PS my target price for all this is $130 for 4 axes / 2 heaters and $150 for an "all dressed" 5 axis 3 heater version.
Possibly less if i get enough interest / reservations.
I'm hoping to finalize the design by the end of the coming weekend so i can order prototypes along with the Heated build plates, so please dont be shy to give me your opinion and suggestions right away!
Cheers