Components

Should be capable of driving robot’s motors: https://www.pololu.com/product/4751

Maximum voltage from 4S battery is 16.8V (4x 4.2V).

Driver does not need to be capable of driving the motor at stall current. Driving the motor at stall current for longer period will overheat the motor.

Motor’s power can be higher than the rated power for a short duration.

Driver should be capable of limiting the current somewhere between the stall current and maximum power limit (where current is 12W / 16.8V).

Should have enough timers:

Should have USB interface or UART/USART interface if USB-UART bridge is used.

TVS diodes compatible with USB voltages and signal speeds.

Should electrically isolate motors' battery from computer’s battery to avoid short circuits on the motor’s side damaging the computer.

Signals between the microcontroller and motor drivers should go through isolator(s).

Needs to work with 3.3V and 5V.

For connecting encoder power and signal wires to the microcontroller.

4 wires for each encoder.

For connecting thrower motor controller.

Only 2 wires (GND and PWM) are needed.

For connecting STLink programmer to the microcontroller.

For avoiding reverse voltage damaging the components.

Should be connected between positive supply instead of ground to avoid having different ground potentials.

Simple and efficient solution is to use P-channel MOSFET.

MOSFET’s drain-source and gate-source rated voltages should be higher than battery voltage.

For connecting power input from battery and outputs from motor drivers.

No separate components are needed.

Simple rectangular SMD pads, where wires can be soldered, take little room and creates a reliable connection.

Pad size can be 3 x 3 mm or larger for 18 AWG wire.

LEDs can be connected to microcontroller and used in firmware to indicate that something is working.

LEDs can also be connected to voltage regulator output to indicate that the board has power.

LED’s brightness is controlled with current. The simplest way to limit current is to use resistor in series with the LED.

LED’s current can be calculated with the following equation: , where V_F is LED’s forward voltage. V_F can be found in the LED’s datasheet.

0603 SMD package.

Current around 1 mA. Higher currents usually make the LED too bright and waste energy. Exact current is not that important if LED is used for visual indication and can be changed later by replacing the resistor.