DoWatch DIY03

Here you should use the pointed welding head.

Turn over the board C, and add some tin to one of the pads corresponding to each component, making it easier to fix the component to the board in welding.

Please notice that there are two kinds of capacitors will be used.

Weld one of the pins of the components to the corresponding position on the board C (For example, the 0Ω resistor are welded to R050).

Weld the rest pins of the components to the board C. Please tale a note to the welding direction of the ICs and the diode 1N4001 should be placed in a correct polarity (The black side of the diode is the passive polarity).

After completed the board C, place the battery to the position LI-ION on the board C, and connect the positive polarity of the battery to the inner fixed hole on the upper left side of the board C with a cable.

Press both ends of the cable to ensure the fixed hole and the battery is in a good connection. And if the OLED screen shows any picture, it means the product works well.
If there is nothing display, please check whether there is any short-out or cold solder of the pins of the MCU and the OLED screen.

In welding the MCU, some pads of the MCU pins may peel off or short out. If the pad peeled off is corresponding to the NC pin, it will not affect the circuit. For more details, please refer to the picture above.

The pads on XTAL do not connect with crystal oscillator, since it is used for remedying exceptions.