32U4 numeric keypad_with two encoders and OLED screen

The minimal system refers to  Lao Xuan’s project at https://oshwhub.com/Neilzx

Inspired by https://oshwhub.com/lnksy/oled_keyboard 

The layout was changed, an encoder was added, and the wiring was optimized (probably).

A small keyboard has been prototyped and verified, but the program does not support encoders and OLED screens yet.

The resistor and capacitor are packaged in 0603, the main control is ATmega32U4-MU, the axis seat is Kaihua axis seat, and the diode is packaged in SOD-323, which is difficult to weld.

The resistance and capacitance values ​​on the front are marked with silk screen printing, and the resistance and capacitance on the back are all 0.1 microfarads except for the markings.

There are two resistors that do not need to be soldered.

    The first place is the two 5.1 kiloohm resistors next to the type-c interface. The function of these two resistors is to report the power supply voltage required to the host when using the c to c data line. When the c to c data line is not used, The data line does not need to be soldered.

    The second place is two 10 kiloohm resistors on the right side of the main control. Because the general OLED screen has its own pull-up resistor, these two resistors do not need to be soldered.

The front of the first version of the circuit board

The back of the original circuit board

The first version of the circuit board had the following problems:

1. I forgot to update the packages of the two uppermost shafts, which resulted in the hole diameter in the center being too small and unable to insert the shafts. This has been corrected.

2. The three-millimeter screws will jam the four-corner shafts, but they have been replaced with two-millimeter screws.

Currently learning to program locally, but it may take a few months.

Go ahead first

——2021.05.21