Revision A of the Reader board

Electrical characteristics

(To be determined)

Soldering guide

This is a recommended soldering procedure. It is designed to help find problems with the board as soon as possible in as local area as possible without wasting components.

Standing recommendation is to check all connections for unintended short-circuits or open-circuits and fix them as soon as possible. Also some steps have some recommended checks to perform. If the board fails those tests the problem must be debugged, and debugging cannot be sufficiently proceduralized to form a manual, therefore it’s up to the creativity of the one soldering the board.

Steps

Solder the Power Supply unit

Solder components IC3, C6, D2, C7, D3, D4, L1, R11, R12, C8 and C9. Check for shorts on the power supply lines. Then connect +5V power source to the PSU and verify that

• the output voltage is 3.3V +- 0.2V
• idle current through the PSU is less than 5mA
• output voltage is stable (with margin of +- 0.3V even if the PSU is loaded with a 330 Ohm resistor
• output voltage is stable through the entire allowable range of input voltages

Solder the MCU

Solder components IC2, C1, C2, C3, R3, D1, R4, R6, JP1, JP2 and JP3. Use STM32F052 for Reader revA and STM32F072 for Reader+ revA. Connect +5V power source to the PSU and SWD debugger and verify that

• current through the board is less than 30mA
• the MCU responds to the debugger

Solder the rest of the board

(Note: If soldering Reader revA (not Reader+ revA) leave out components D7, R13, R14, R15 and X1)

Connect +5V power source to the PSU, SWD debugger and communication interface and verify that

• current through the board is less than 100mA
• all tests form hw-testing repository file tests/test-reader-revA.py pass