MiniRambo
Release status: Working
Description | Smaller version of RAMBo with 4 stepper drivers.
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License | Creative Commons Attribution-ShareAlike 3.0
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Based-on | |
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CAD Models | |
External Link |
RAMBo Pages: RAMBo .:. RAMBo v1.0-1.1 .:. RAMBo v1.2 .:. RAMBo Firmware .:. RAMBo Development .:. MiniRambo .:. MiniRambo Development
Contents
Summary
This board is based off RAMBo, the Arduino MEGA design, and the work of RepRap community. It has 4 stepper drivers and 4 mosfet switched outputs.
Differences from Rambo
MiniRambo has:
- 4 stepper drivers vs. 5
- 3 Thermistor jacks vs. 4
- 4 total mosfets vs. 6
- PWM control of stepper current vs. Digital Trimpot
- Can connect RepRapDiscount LCD cables directly without an adapter board. (v1.3a+)
- Less general purpose IO connectors than Rambo.
Powering Mini-Rambo
MiniRambo you must connect power to the Primary Power input for RAMBo to operate. The USB connection is isolated from the rest of the board and cannot be a power source.
Features
Logic
- Arduino MEGA compatible Atmega2560 and Atmega32u2 processors are compatible with all RAMPS class firmware
- Crystals for both usb and mcu (timing accurate to 10ppm)
- 3 Thermistor jacks
Motor Drivers
- 4 A4982 1/16th microstep motor drivers(2 connectors on Z for Prusa Mendel and other dual Z printer designs)
- PWM Outputs for (XY), Z, E0 stepper current control instead of digital trimpot.
- Current limit on driver IC VCC to prevent permanent latchup
- Microstep mode configured by MCU through firmware (no jumpers needed)
- Test points for driver control signals
- Step and Direction pins are on their own ports for synchronous movement capability
PWM DC outputs (Extruders, Fans, Etc.)
- 4 outputs (1 Extruder, 1 BED, 2 low power (fan,etc)
- Low resistance mosfets for cool running
- Indicator led for each channel
Power
- 2 power input rails
- Heated Bed, 15A 12-35V
- Primary Power 10A 12-28V: Motors (5A dedicated fuse) + Extruders, Fans, & Logic (5A dedicated fuse)
- Built in SMPS for 5V generation from Extruders + fans and logic
PCB
- 4 layer
- 2oz copper on all layers
- High quality, High temperature FR4-TG130 PCB
- Gold ENIG finishing
Schematic
Fuses
MiniRambo has 3 user replaceable ATO fuses (the type found in many automotives).
- F1 5A supplies the motors.
- F2 5A supplies the extruder heater + fan outputs and logic.
- F3 15A supplies the heated bed output.
Firmware
Marlin 1.0.2
fork with Thermal Runaway Protection during heatup phase
https://github.com/tonokip/Marlin/tree/1.0.2-TRP
This firmware requires a change in Configuration.h:
#define MOTHERBOARD 302
Marlin development branch
https://github.com/MarlinFirmware/Marlin/tree/Development
This firmware requires a change in Configuration.h:
#define MOTHERBOARD BOARD_MINIRAMBO
REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER
Using this LCD controller requires a fix in Marlin source code. In the file "ultralcd_st7920_u8glib_rrd.h" change this line:
#pragma GCC optimize (3)
To:
#pragma GCC optimize (0)
USB Driver
Mini-Rambo uses the same Windows CDC driver as the RAMBo USB driver.
Troubleshooting
This is a generic troubleshooting guide. These steps may vary depending on manufacturer configuration. Contact your supplier if these steps do not help.
- Cannot connect with 3D printing control software
- Is the power indicator LED on?
- Make sure the power is connected as described in :Powering Mini-Rambo.
- Is a fuse blown? MiniRambo fuses
- Is correct driver installed? RAMBo USB driver
- Is there firmware installed on your Mini-Rambo? Mini-Rambo firmware
- Is the power indicator LED on?