Assembling "Main PCB": Programming and first tests

After "Main PCB" is assembled we need to test working of the MCU.

1. Connect external +5V power lines to the "GND" and "PWR+" pads at the PCB.
2. Connect programmer to the J1 (3.5mm Jack) or J2 (PLS-3) connectors. Both connectors are SWD. You can use any of them.
3. Ensure that MCU is accessible by programmer software.
4. Load "test_encoder_blinking" firmware to the MCU.
5. Ensure that LED is blinking at power-up.

Firmware is loaded to the MCU using any SWD programmer that is supporting STM32.
You can use, for example, original ST-Link, any kind of STM32FXXX-Discovery board - they have integrated ST-Link programmer, or cheap Chinese ST-Link clone.
"ST-Link Utility" could be used for flashing HEX file. Needed HEX file is placed here: LINK
J1 pinout: Sleeve - ground, Ring - SWCLK, Tip - SWDIO.
J2 pinout is written at the board in silk layer.