Gen7 Board 1.0

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This page describes something which is no longer the most recent version. For the replacement version see: Gen7 Board-AVR 1.5

Gen7 Board History   --   Gen7 Board is part of Generation 7 Electronics
Crystal Clear action run.png
Generation 7 Electronics Board

Release status: working

Gen7 Board 1.0 Layout.png
Generation 7 Electronics
GPL v2
CAD Models
External Link

How to get it


Get Gen7 Board PCBs from Traumflug.

As Gen7 is designed to be manufactured on a RepRap, you can make PCBs yourself, of course. How to do this on a RepRap or a general milling machine is described on the Gen7 main page. You want one "Gen7Board" PCB and up to six "Endstop" PCBs.

Yet another way is to purchase from one of the many houses specialized in manufacturing prototype PCBs. Gen7 is single sided, so this won't cost a fortune.


Get Gen7 Components Kits and Gen7 Connectors Kits from Traumflug.

If you want to assemble the collection yourself, see the #Parts Lists section.

Parts Lists

To assemble or verify these lists, open the layout with gEDA/PCB and export a "BOM". This will give you a list of all required components.

Special considerations:

  • The Pololu Stepper Drivers want two single rows of 8 pin female connectors soldered into the board, so get these.
  • The Pololu Stepper Drivers come with their male headers, so there's no need to purchase them seperately.
  • Don't forget enough (8-9) jumpers for the jumper headers.
  • Resistors with 0.25 W are on the safe side, even if the footprint name reads "0.125".
  • The Pololus can be operated with up to 35 V, so you may want like-rated electrolytic capacitors.
  • You may want to add the cable side of the connectors, their crimp pins and some wire.

Electronic Components

Name Count Designations Remarks
Resistor 180 Ohms 2 R16, R18
Resistor 560 Ohms 3 R14, R22, R23
Resistor 1 kOhms 7 R2, R6, R8, R10, R11, R12, R13
Resistor 4.7 kOhms 2 RT1, RT2
Resistor 10 kOhms 3 R1, R3, R30
Ceramic Capacitor 22 pF 2 C3, C4
Ceramic Capacitor 0.1 uF 12 C5, C8, C9, C10, C11, C12, C13, C14, C16, C17, C18, C19
Electrolytic Capacitor 10 uF 2 CT1, CT2
Electrolytic Capacitor 100 uF 3 C1, C2, C6
Coil 100 uH 1 L1
Diode 1N4004 3 D1, D2, D3
LED 3 mm Green 5 LED2, LED3, LED4, LED5, LED6
Crystal 16 MHz or 20 MHz 1 U6
Reset Switch 1 RESET
Socket for the ATmega 1 U1
ATmega 644 (or 644P) 1
MOSFET TIP120 3 Q1, Q2, Q3
0.6 mm Wire 50 cm for the wire bridges of single sided PCBs


Name Count Designations Remarks
Motor Header Molex 26-48-1045 (4 Pin) 4 X_MOT_0.156, Y_MOT_0.156, Z_MOT_0.156, E_MOT_0.156 This is the one also used in Gen2 and Gen3 Electronics
Cable Connector for the above 4
Crimp Contact for the above 16
Alternative Motor Header 4 X_MOT_0.156, Y_MOT_0.156, Z_MOT_0.156, E_MOT_0.156 working, but incompatible alternative to the Molex 26-48-1045
Cable Connector for the above 4
Crimp Contact for the above 16
Jumper Header 2 Pin Pairs 4 pair J2/J3, J5/J6, J8/J9, J11/J12 cut them into appropriate pieces
Jumper Header 2 Pin 3 J13, J14, J15 cut them into appropriate pieces
Jumper for the two above 9
ICSP Header 1 CONN6 alternatively, assemble this out of the remainings of the Jumper 2 Pin Headers
Misc Header 1 MISC cut them to appropriate length
Pololu Header 8 or 4 U2, U3, U4, U5 cut them to appropriate length, you want 8x 8 pins
Disk Power Header 1 CONN2
ATX20 Power Connector 1 CONN1
Molex KK100 3 Pin Header 12 HEATER1, HEATER2, FAN1, TEMP1, TEMP2, I2C, X_MIN, X_MAX, Y_MIN, Y_MAX, Z_MIN, Z_MAX Reichelt are tested to be fully compatible with Molex
Cable Connector for the above 12
Crimp Contact for the above 36
Molex KK100 6 Pin Header 1 SERIAL alternatively, use the same as for Jumper 2 Pin
Optional: Cable Header for the above 1 only needed if you intend to solder your own USB-to-TTL cable
Optional: Crimp Contact for the above 6 only needed if you intend to solder your own USB-to-TTL cable
Heatsink for the Pololus 4
Cyanacrylate Glue 4 drops for glueing the heatsinks onto the Pololus


Generation 7 Electronics uses a TTL header for serial communications to the host. As many modern PCs lack a serial port, these need an appropriate USB to TTL cable:

USB to TTL Cable Mouser Adafruit Industries MAKE Store MakerBot Industries Watterott

An alternative to the USB to TTL cable is the same electronics in form of a small breakout board:

USB to TTL Breakout Board Watterott Sparkfun
Cable for the above Watterott

Assembly Instructions

  • To find out which components to put where, have the layout on your PC screen available.
  • PCBs fabricated with Voronoi paths need more heat, so raise your soldering iron's temperature by about 20 deg Celsius.
  • Start with the flattest parts, usually wire bridges or resistors. This way, components won't fall out when you lay the PCB on it's front for soldering. Then continue with parts of raising height, connectors are usually among the last ones.
  • To ease soldering jumper headers and similar components, put a small drop of cyanacrylate glue onto the component side before inserting them. As the PCB is single-sided, this won't hurt the solder point.

Gen7 Mainboard Front.jpeg Gen7 Mainboard Back.jpeg

The pictures show the soldered 1.1 board, semiconductors not yet inserted. 1.1 has a few different tracks between the MOSFETs and the ATmega. It's a good idea to check supplied voltages before inserting them.

  • The coil 100 uH looks just like a resistor. It's a bit thicker and comes with rings brown-black-brown.
  • Start with the 10 wire bridges, then follow the table in the parts list.
  • As 8 pin headers for the Pololus are expensive, many kits come with lower cost 10 pin headers. Cut 2 pins off of each.
  • While soldering a pair of these headers, insert a Pololu to ensure good alignment.


These steps show how to get from a soldered mainboard to a working one.

Power Source Selection

Gen7 Board PSU Selection.jpeg

The picture shows an v1.1 board. Boards v1.0 has only one jumper in this area, which equals the "Molex 4 Pin" one. Insert the jumper and make sure the ATX20 connector is free if you supply the ATmega through the Molex 4 pin connector. Let the jumper header free when the ATX20 is inserted.

The lack of a jumper for the 5V coming through the serial line is a flaw in the 1.0 design. You should cut off pin #3 of the serial header, as the 5V coming from the serial line sometimes conflicts somewhat with the 5V coming from Gen7's own PSU.

Power Supply Checks

If you want to do some extra checks to confirm you soldered correctly before inserting semiconductors, insert the power source selection jumper as explained above and hook up your type of power supply.

No smoke? Great, then take a few measurements:

Gen7 Board Power Checks.jpeg
  • Red: power supply inserted. In case of an ATX20 PSU, PSU not yet activated.
  • Blue: as above, with ATX20 PSU activated (bridge between pin 14 PWR_ON and GND).
  • Green: as above, with the Molex 4 Pin also inserted.

Even those without a voltage meter can have a look wether and when one or two LEDs light up.

That done, you can solder in the MOSFETs and plug in the Pololus and the ATmega.

Preprare your Arduino IDE

If you fire up your Arduino IDE now, you should be able to select your variant of Gen7 board under Menu -> Tools -> Board.

Bootloader Upload

Note: this section only applies if you have a blank, factory fresh ATmega on your board. Friendly Gen7 vendors will do these steps for you before shipping, so you don't need a programmer.

How to go:

  • Disconnect all connectors, including the power supply.
  • Insert the ATmega644 into it's socket. Make sure you do it the right way, the small nut on the housing goes towards the heater connectors, the numbers on the housing can be read looking from the ATX20 connector side.
  • Re-connect the power supply.

Note: The pins used for the programmer conflict with the pins used for the X_MAX, X_MIN and Y_MIN endstops. This isn't an issue in normal operation, but make really sure you have these endstops disconnected before hooking up the programmer.

  • Connect your programmer. Again, watch out for insertion of the plug the right way.

Now you should see something like this - the red LED indicates the PSU is still without juice:

Gen7 Programmer Setup.jpeg

Programming the bootloader using the command line

  • Have your Arduino IDE prepared for Gen7, as explained above.
  • Connect your power supply, at least one of the power connector indicators should be lighted.
  • Open a terminal and change directory into Arduino IDE's folder. All required tools are there, even if you haven't installed them system-wide.

The following sequence was done on Linux and should apply similarly on other OSs. Unlocking and locking the bootloader section is done on Arduinos, it's not done here.

cd hardware/tools
./avrdude -C ./avrdude.conf -c ?  # find your programmer, e.g. "avrispv2"

### For the ATmega644:
# write fuses
./avrdude -C ./avrdude.conf -c <your programmer> -p atmega644 -P /dev/ttyACM0 \
    -B 5 -U lfuse:w:0xF7:m -U hfuse:w:0xDC:m -U efuse:w:0xFF:m
# upload bootloader
./avrdude -C ./avrdude.conf -c <your programmer> -p atmega644 -P /dev/ttyACM0 \
    -B 1 -U flash:w:../Gen7/bootloaders/Gen7/bootloader-<your variant>.hex

### For the ATmega644P:
./avrdude -C ./avrdude.conf -c <your programmer> -p atmega644p -P /dev/ttyACM0 \
    -B 5 -U lfuse:w:0xF7:m -U hfuse:w:0xDC:m -U efuse:w:0xFF:m
./avrdude -C ./avrdude.conf -c <your programmer> -p atmega644p -P /dev/ttyACM0 \
    -B 1 -U flash:w:../Gen7/bootloaders/Gen7/bootloader-<your variant>.hex

Watch your programmer a few seconds blinking and you're done.

Programming the bootloader using Arduino IDE

-- Yet to be found out --

Debugging hint: Arduino obviously doesn't attempt to use the "-B 5" flag when writing fuses onto a factory fresh chip. This is needed if the programmer was set to a higher speed earlier, as an ATmega running at 1 MHz (factory default) can't keep up with 115200 baud.


./avrdude -C ./avrdude.conf -c <your programmer> -p atmega644p -P /dev/ttyACM0 -n -v

Serial Connection

It's recommended to either use a USB to TTL cable or USB to TTL breakout board. Custom solutions are possible, see Customisations.

Here's how you connect them, GND is always the pin to the left:

Gen7 Serial Connection With USB2TTL Breakout Board.jpeg Gen7 Serial Connection With USB2TTL Cable.jpeg

Simply plug the connector in, connect USB to your PC and a new serial port should show up in your PC's operating system.


Last not least, you probably want to set up microstepping to something other than the default. The default is halfstepping. Smaller microsteps make the motors run smoother, but also raise the computing load for the ATmega. The smallest steps possible are 1/16 microstepping.

Feel free to select different settings for each of the motors, e.g. 1/8 microstepping for threaded rod axes (Z) and 1/16 microstepping for belt driven axes (X, Y).

Selecting microstepping is done with the jumpers in front of each of the Pololus, they refer to MS2 and MS3. Allegro documents also know about MS1, which is hard wired to High in Gen7. Plugging a jumper sets High, while leaving the header free sets Low. Here's a detail picture of a Gen7, with MS2 set to High, MS3 set to Low:

Gen7 Microstepping Jumpers.jpeg

The following table shows what you get with each combination:

MS2 MS3 Microstep Resolution
Open Open Half step
Open Plugged Not allowed!
Plugged Open Eighth step
Plugged Plugged Sixteenth step


In principle, you can run any of the RepRap Firmwares on this board. Adjust the I/O pin layout, adjust compile time options for no secondary board/no RS485 and proceed. Just like Gen2, RAMPS or similar electronics.

Teacup Firmware

Teacup's Simple Installation instructions show nicely how to do this. Two additional tweaks are required for Gen7:

  • Have your Arduino IDE prepared for Gen7, as explained above.
  • * Use the config.gen7-v1.1-v1.3.h and ThermistorTable.double.h you find there.

With config.h left untouched, at least something should move. This is fine for first tests, but not sufficient to have everything right for your machine. Edit your config.h further to match your machine and your setup. Config.h has a lot of comments inside the file, helping on the details. For example, STEPS_PER_MM_X should be set according to your choice of microstepping. Also, default maximum speeds are very slow, you likely want to raise MAXIMUM_FEEDRATE_....

FiveD Firmware

FiveD has been run succssfully on Gen7. No installation instructions yet, though. If you want to try yourself, start with adjusting the pin layout in configure.h, see the next section, "Other Configurations".

Other Configurations

The following should help to configure other firmwares.


pin bindings
Function ATMega Name Teacup Original firmware Direction in firmware
X Step PC3 DIO19 19 Digital Output
X Direction PC2 DIO18 18 Digital Output
X Min PB7 DIO7 7 Digital Output
X Max PB6 DIO6 6 Digital Output
Y Step PC7 DIO23 23 Digital Output
Y Direction PC6 DIO22 22 Digital Output
Y Min PB5 DIO5 5 Digital Output
Y Max PB4 DIO4 4 Digital Output
Z Step PA5 DIO26 26 Digital Output
Z Direction PA6 DIO25 25 Digital Output
Z Min PB3 DIO3 3 Digital Output
Z Max PB2 DIO2 2 Digital Output
Extruder Step PA3 DIO28 28 Digital Output
Extruder Direction PA4 DIO27 27 Digital Output
Power Enable PD7 DIO15 15 Open Drain Output, active low
Motors Enable PA7 DIO24 24 Digital Output
Heater 1 PA0 DIO31 31 Digital Output
Heater 2 PB0 DIO0 0 Digital Output
Fan 1 PB1 DIO1 1 Digital Output
Temp 1 PA1 AIO1 1 Analog Input
Temp 2 PA2 AIO2 2 Analog Input


This part describes possible modifcations for advanced users only.

Serial Connection

If you want a custom solution, you can create one, of course. Just connecting an RS-232 port to the serial connector won't work, however, even if you ignored the different voltage levels. ATmega's serial signal is inverted (Logical 0 = 5V, Logical 1 = 0V). Here's the serial connector's pinout:

Gen7 Serial Pinout.png


1 2 3 4 5 6
GND CTS (set to GND) +5 Volts RxD TxD Reset

RxD is ATmega's pin 14 (data to the chip); TxD is ATmega's pin 15 (data from the chip).

With pin 3 you can feed the ATmega, if you have no other current source. If you have another current source, e.g. your power supply, you might have slightly different potentials of 5V though, so you better keep this pin unconnected. As of version 1.1, the board comes with a jumper to make sure no bad things can happen.

Pin 6 is usually connected to the serial line's DTR. This triggers a reset each time you start a connection to the ATmega and is very convenient when uploading firmware - no pressing of the reset button needed, then. Arduinos have this hardwired. If you keep pin 6 free, press the reset button each time your IDE (avrdude) attempts an upload.