Assembly the board

Soldering the electronic components on the d-diot boards requires about 2-4 hours of your time, depending of your soldering skills (I'm a totally noob), but it is a quite fun operation.

Most parts are SMD components with 0805 package, so you have two options to solder them:

  • Hand soldering with soldering iron and wire (you must be a soldering iron hero‚Ķ)

Soldering the ATMega2560 with its 100 pins in TQFP package seems an impossible task, but if you follow the drag soldering technique described below, you will realize that it is a feasible operation even for a noob (my personal experience).

Soldering the through-hole components can be easily done with a simple soldering iron and solder wire.

In any case:

Use the interactive BOM tool to see where to place each component

This video shows how to solder SMD components, with both techniques, soldering iron and hot air.

MP1584

Before you start soldering parts, it is convenient to regulate the output voltage of the MP1584 step down voltage regulator and MT3608 step up voltage regulator.

The scope of the MP1584 step down regulator is to power the IR LED. If you use this type of IR LED reported in the required hardware page:

the voltage of the MP1584 has to be set to 1.5V

The voltage adjustment is done through the screw of the potentiometer (see below)

MP1584 step down voltage regulator

The output of the MP1584 is connected to the D+ pin of the USB port J3, so additional IR LEDs can be added to extended the coverage of the IR signal. See the schematics to know what is connected to the other PINs of the USB port.

If you your LEDs configuration require 5V, you can power that simply not installing the MP1584 and then bridging the input + and output + holes of the footprint with a wire.

MT3608

The scope of the MT3608 step up voltage regulator is to power The FS1000A 433 MHz transmitter (RFLink).

The working voltage of this component is 3V - 12V, but the transmission power and the distance covered by the signal increase with the voltage, so:

the voltage of the MT3608 has to be set to 10V - 12V

My FS1000A was not working properly with 12V so I have set the output voltage of the MT3608 to about 11V and all is working as expected. The voltage adjustment is done through the screw of the potentiometer (see below)

MT3608 step up voltage regulator

For hand soldering you need a soldering iron and solder wire. A good pair of tweezers is recommended if you wont to solder the 0805 components.

Soldering iron
Soldering wire

To work with this technique a hot air soldering station is required. On the market you can find many models and also soldering stations that combine an hot air gun and a traditional soldering iron in the same device.

Combo soldering station with hot air gun, iron solder, voltmeter and amperometer

You need also the solder paste. Once opened the primary packaging store the paste in the fridge and take it out 2-3 hours before the use.

Solder paste in syringe
Solder paste in bottle

The solder flux agent is fundamental for the success of the operation. You can use either a flux pen or flux paste, but, in both cases a no-clean type is preferable, because with this type you don't have to worries about the corrosion of the board and traces caused by unwanted residues.

Flux pen
Flux paste

The best way to learn how to solder the ATMega2560 microcontroller with the drag soldering technique is watching the videos below

Tutorial:

A very professional and perfect execution:

In the d-diot board are present 6 jumper. See the table below for the function of each jumper and its default configuration.

Ref. Name Description and function Default config Component
JP1 Jumper 1 PIN 1 (JP3) is connected to PIN 3 of the Jumper 3
PIN 2 (P26) is connected to GPIO PIN 7 of the Raspberry Pi (PIN 26)
PIN 3 (ACT) is connected to the activity LED D13
It is an optional jumper because the GPIO PIN 7 of the Raspberry has the function of cs1 pin of the spi0 bus.
At the best of my knowledge at the moment is not possible to free the Raspberry Pi GPIO PIN 7 from this function without a custom dtoverlay
Open Vertical PIN header, 2.54 mm pitch
JP2 Jumper 2 PIN 1 (IRQ) is connected to the IRQ PIN of the NRF24L01 radio module
PIN 2 (P33) is connected to GPIO PIN 13 of the Raspberry Pi (PIN 33)
PIN 3 (RST) is connected to the reset circuit of the ATMega2560
In normal operation bridge PIN 1 and 2, bridge PIN 2 and 3 when you have to flash a firmware into the ATmega2560 through the GPIO serial interface of the Raspberry PI
Bridge PIN 1-2 90 degree PIN Header, 2.54 mm pitch
JP3 Jumper 3 PIN 1 (GND) is connected to ground
PIN 2 (RST) is connected to the reset PIN of the RFM69 radio module
PIN 3 (JP1) is connected to PIN 1 of the Jumper 1
It is an optional jumper with the recommended RFM69 radio module. Some other radio modules need reset PIN connected to GND.
Open Vertical PIN Header, 2.54 mm pitch
JP4 Jumper 4 When PIN 1 (ON) and PIN 2 are bridged, the d-diot hub turn on when you insert the power plug
When PIN 3 (OFF) and PIN 2 are bridged, the d-diot hub stay off when you insert the power plug
Bridge PIN 2-3 Vertical PIN Header, 2.54 mm pitch
JP5 Jumper 5 PIN 1 (RX3) is connected to RX3 PIN of the ATMega2560 (PIN 63)
PIN 2 (FS+) is connected to the Vcc PIN of the FS1000A radio module
PIN 3 (Reg+) is connected to the VOUT+ of the MT3608 step up voltage regulator
Bridge PIN 1 and 2 if you wont to power the FS1000A with 5V, avoiding the MT3608 voltage regulator
Bridge PIN 2 and 3 if you wont to power the FS1000A with 10-12V provided by the MT3608, for a better signal range
Bridge PIN 2-3 Vertical PIN Header, 2.54 mm pitch
JP6 Jumper 6 PIN 1 (PWR) is connected to 5V power line
PIN 2 (VCC) is connected to the Vcc circuit of the ATMega2560
Bridge this jumper to power the ATMega2560. Keep them open when you power the ATMega2560 through the FTDI or ICSP connector.
Bridge PIN 1-2 Vertical PIN Header, 2.54 mm pitch

Solder a piece of solid wire with a length of 16.8 cm or a 433 MHz spring loaded antenna to your FS1000A module to improve the transmission range.

Spring loaded antenna
FS1000A radio module without antenna
FS1000A radio module with antenna

Solder two wire (+ and -) to heatsink's pad of the 940nm 3W IR LED and connect them to the corresponding PINs of the J4 connector in the d-diot board.

Connect the two wires (+ and -) of the fan to the corresponding PINs of the J2 connector in the d-diot board.

Below my fully assembled d-diot board:

The schematics of the d-diot board is available for download in pdf format.

  • getting_started/hub_v1.0/2_assembly_the_board.txt
  • Last modified: 2019/06/06 21:53
  • by franzunix