NGBLC-4mini

About

Why we built our own BLC

The UAVP-NG Multicopter Project had no own brushless controller for a long time. As the NGOS supports I2C driven brushless controller from other Quadrokopter projects like the MK-BLC (Mikrokopter) or 1hoch4 BLC (1hoch4) as well as modded chinese brushless controllers (which use the BLC firmware from Bernd Konze aka Quax), we had no pressing need for our own BLC design.

This changed when the chinese suppliers started changing the design of their BCLs in rapid succession, making modification harder and harder. So we decided to design our own BLC, specially adapted to our needs and wishes. Placing 4 BLC on one PCB helped us to use less space and to loose weight as we use less cables to connect the BLCs.

Specification

• 4 brushless controllers on one 55x55mm PCB (same size as the Mini-NG PCB)
• Quax firmware compatible hardware
• Power up to 30A
• 16MHz ATMEGA CPU

• 2 - 4 LiPos / LiFePos

• I2C and UART interface
• Input cable reduced to:
• * 1 battery input (+/-)
• * 4 Pin I2C or 6 Pin UART connector (5V,SCL,SDA,GND,RXD,TXD)

Power Supply Options

1. 5V Power coming from our Flight Control. The BLC needs no own Power Supply. The Flight Control switches ON and OFF the BLC. Batteries will be protected from discharging long time since the shutdown current is minimised.
2. 5V Power Supply on the BLC. It is switched On and OFF by the 5V signal from the FC. Batteries will be protected from discharging long time since the shutdown current is minimised.
3. 5V Power Supply on the BLC. It is always on. This allows the use of our NGBLC with other Flight Controls like Mikrokopter or Armocopter. It is NOT switched OFF. You have to protect your battery on your own.

PCB Assembling

Soldering this PCB is not easy and certainly not possible for beginners. Do not attempt this if you have no experience in soldering small SMD parts. Expect additional difficulties in getting enough heat to solder the parts on the board because of the large amount of copper inside the PCB. You need a LARGE soldering-iron-tip for soldering this board.

Order of soldering

1. MOSFETs
2. Oscillator
3. Capacitors between Half-Bridge-Drivers
4. Half-Bridge-Drivers
5. ATMEGAs
6. all Ceramic Capacitors, C17 is too near to IC5 and has to be soldered at the edge of the pads in the direction of IC7
7. all Resistors
8. all Diodes and LEDs
9. Presicion Resistors
10. Electrolytic Capacitors
11. Molex Picoblade Connectors
12. Step-Down Switching Regulator

Empty Boards

FETs

Start with soldering the FETs. They are not easy to solder, since both the FETs themselves and the large copper patches on the PCB below them are HUGE heatsinks. Use a wide soldering-iron-tip, and turn your iron up to 350 degree C. Do not attempt this if your sodlering iron has less than 60W.

If you don't have any hot-air soldering station available, you can just pre-tin the large Pads below the FETs, and slide the FETs slowly on the Pads from the center of the PCB while keeping your solering iron on the Pad an on the top edge of the heat-sink of the FET simultaneously.

Half-Bridge-Drivers and Atmegas

Contrary to the pictures, start with soldering the Capacitors between the FET drivers. As you can see on the pictures, space between the FET-drivers is very limited. The Continue with the FET-drivers and the Atmegas.

Small stuff: Resistors, Capacitors

Now continue with all the small Resistors and Capacitors. Since the Diodes have legs, they are easy to be soldered from above, so solder them after all the Resistors and Capacitors.

Large Resistors, Capacitors, Connectors

Now solder on the remaining LEDs, large Capacitors and large Resistors. Solder the picoblade connectors after everything else is finished, since they are temperature-sensitive and block access to a few other parts.

The fully assembled NGblc-4mini PCB

Jumper

The Jumpers SJ1 and SJ100 are needed to select the 3 Power Supply options from above

1. SJ1 1-2 closed, SJ100 open
2. SJ1 2-3 patch, SJ100 open, there has to be a patch with 2x 1N4148 diodes in series from pad 2 to pad 3 (or do it from connector X1 pin4 to pad 3)
3. SJ1 open, SJ100 closed

Flashing

As software for compiling and flashing i am using Atmel AVR Studio 4 (don't use version 5, only trouble)

Download AVR Studio 4 - Registration needed

As programming device you may use Atmel AVR Dragon or USBprog. Mine is USBprog 3.0

USBprog Hardware

The cable has to be configured as following

Fuses of the ATMEGA168

Testing

Partlist

NGBLC-4mini-partlist