RDB-STPTS-002-DIY

From RepRap
Revision as of 11:29, 20 September 2014 by NoobMan (talk | contribs)
Jump to: navigation, search
RDB Build Documentation
Crystal Clear action run.png
RDB Reprap Development Board

Release status: experimental

No image available.png
Description
Generic reprap extension for generic development board
License
Author
Contributors
Based-on
Categories
CAD Models
External Link


This board is meant to take GPIO lines (wires,cables,connectors etc) from the development board and provide the support components required for basic operation of a 3d printer.

  • Pcb size: 160x100mm
  • Voltage regulator: 3, fixed
  • Support components for: 5 pololu drivers, 4 thermistors, 3 endstops, and 4 switches (low side mosfets) with dedicated drivers and optoisolators
  • optimized for DIY: single sided, no bridges, large clearance 0.5mm, min track width 1.5mm, format and traces "bulky" enough so board could be made with any diy technique.



Power input 1, for steppers, dev board, logic level

  • this connector supplies steppers, has a voltage regulator output meant to supply the dev board itself, and another voltage regulator providing the local logic level voltage
  • input simple reverse polarity protection with high current diode and fuse
  • input simple peak voltage burner with zenner and transistor meant to flat off peaks made by steppers switching or bemf
  • 12v-32v input voltage (max input voltage depends on the burner zenner voltage, regulators used and stepper drivers max input)

Power input 2, for low side mosfets

  • this connector supplies the low side mosfets (switches)
  • input simple reverse polarity protection with high current diode and fuse
  • if this psu is different than the first one, then optoisolators ICs must be equipped in order to provide galvanic isolation
  • 12v-16v input voltage (max input voltage depends on hexfet breakdown Vbr, regulators used and most limiting factor the fet drivers and optoisolators inputs max)

Functions

  • Outputs from two voltage regulators
    • Output for development board supply
    • Output of logic level
  • Steppers
    • This board is meant to support pololu carrier stepper drivers, currently using A4988 or DRV8825 stepper driver ICs. Further documentation on pololu carrier drivers at pololu website and Pololu_stepper_driver_board and other places
    • Each driver has a logic input connector with Step/Dir/Enable, and outputs with led indicators
    • Enable default state (when undriven): driver carriers make enable low, to keep outputs always on. Board reverses this behavior. So outputs will be off by default, and then enable line needs to be actively driven low. This was considered a safer approach.
  • Thermistors
  • Endstops
  • Switches (vdc, low side mosfets)
    • Each mosfet connector provide directly both V+ (fused) and switched gnd


Soldering

Soldering tips and tricks:

  • ensuring consistent alignment of the carrier headers: if headers are soldered individually, end up having different angles, and later on it will be hard (mechanically) to switch carriers from one header to another; two 40 pins rows of male '100 pins can be used to align all carriers, and 3 carriers can be soldered on these, to ensure 90 degrees angles and that all headers align to each other;
  • ensuring the bus bars soldering does not warp the pcb (too much): when soldering the bus bars get heated (expand in length) and later on when cooling down they shrink and will tend to warp the pcb; to avoid this, either solder the bus bars with the pcb bent in the opposite direction, or try create sharp bends in the bus bars to relieve the dilatation effect when it takes place; also use just 1mm2 solid conductor, exagerating its size makes the warping worse.
  • after headers and bus bars, soldering priority goes first to all smd components on the back and then to all other through hole components which are not specially sensitive; the through hole ICs should be soldered last; on the other hand the big through hole electrolitic capacitors can be soldered at any time: because this board does not have any soldering on the front then big components dont restrict iron access to anything.


Source files

Name Size (mm) Comments Layout pdf Schematic pdf Kicad zip Kicad version Date
RDB-STPTS-002-DIY 160*100 ~ ~ ~ git source bzr-5139 2014 Sept