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Release status: prototype

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Sanguinololu Upgrade Module V1.0
CAD Models
External Link

SLUM or "Sanguinololu Upgrade Module" is an add-on board for the Sanguinololu control board. SLUM allows the Sanguinololu to control an additional extruder motor, hot end and thermistor, as well as a controllable cooling fan. It is designed to allow signal pass-through for devices which use the pins on the SPI connector and/or the TX/RX pins of the expansion header such as SWA and SDSL.

As of the time of this writing there is currently no firmware which will take advantage of SLUM, however efforts are underway to make a configuration section in Marlin firmware to take advantage of the dual extruder and cooling fan feature.


The stepper motor control is provided by a pluggable Pololu stepper driver board which runs on the same 12v source as the Sanguinololu board. The thermistor and hot end driver circuits are both derived from those on the Sanguinololu, allowing for consistent behavior. The cooling fan and hot end are both driven by power MOSFET transistors, with an optional small signal transistor for cooling fan PWM speed control when a compatible fan is used.

All pins from the SPI header are routed to a second pass-through SPI header at the top of the board. Several pins from the Sanguinololu expansion IO header are used for control of the stepper driver, thermistor, hot end and fan. The A0, TX and RX pins, along with all power supply pins are routed to the pass-through IO header at the top of the board. This should allow compatibility with existing versions of SWA and SDSL devices.


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Source Files

The following file contains the EAGLE format board and schematic for the SLUM 1.0 design.


SLUM source files are released under the GPL license. SLUM is a design derived from parts of the Sanguinololu 1.3a by Joem

Known Issues

The SLUM version 1.0 fan control circuit will not work as configured. The circuit was intended to control 4-pin PWM fans. Most existing firmware with fan support only uses 3-wire fans without the fan interface and do not provide fine control over PWM timing as required by the PWM fan specification. Furthermore, the fan PWM control transistor was wired to +12v instead of +5v as required by the specification. Anyone making a version 1.0 board and intending to use a fan should make one of the following modifications:

1. Cut the +12v trace to the small signal transistor T1 and solder a jumper to one of the +5v pins. This will be suitable if you want to use a 4-pin PWM fan and are willing to modify the firmware to get the PWM timing correct. A lower resistance pull-down resistor to replace R4 may also be necessary.

2. Cut the trace between the 14-pin header and the R4 pull-down resistor (on top side of the board). Do not install T1, R5, R6 or R7 as these are only required for 4-pin control. Add a jumper or resistor from the lower pin of R6 to the upper pin of R4 to redirect the signal to the main fan power mosfet.

Solution 2 is probably the most practical and cost-effective and will allow PWM control that is compatible with Marlin and other existing firmwares. Any boards in my initial sample production run will be modified to ensure proper functionality. A version 1.1 design with these corrections will be posted at a later time.

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