Control Module 2

This section describes the Control Module 2, based on the STM32L412 ARM® Cortex-M4® microcontroller by STMicroelectronics.

It's a small, two-layer, single-sided PCB (≈49.5 mm × 55 mm) containing the main controller of the inverter, a reference voltage source and a temperature sensor.

The module has 41 pins in a standard 2.54 mm (0.1 inch) pattern.

Requirements for the control module:

• 8 analog inputs, 12 bit resolution, preferably 2 separate ADC's on the microcontroller for simultaneous sampling of current and voltage
• 2 reference voltage outputs (V_ref, $\frac{1}{2}$ V_ref): for single ended measurements and for AC measurements that require an offset
• filtered 3.3 V output for analog circuits
• 7 PWM outputs
• 2 digital outputs for LED control
• UART Tx and Rx
• I²C data and clock

Module Pin Table

Pin Number	Pin Name	Electrical Property	Description
1	+3V3_ANA	Power output	Provides 3.3 V analog power
2	1V25_REF	Power output	Provides 1.25 V reference voltage
3	2V50_REF	Power output	Provides 2.5 V reference voltage
4	AGND	Power output	Analog ground. Do not connect on the board to digital ground!
5	AC_grid_Vtg	Input	Analog input for AC grid voltage measurement. 3.3 V max!
6	Relay_Ctrl_Vtg	Input	Analog input for AC voltage measurement between the grid relays. 3.3 V max!
7	AGND	Power output	Analog ground. Do not connect on the board to digital ground!
8	DC_Link_Vtg	Input	Analog input for DC link voltage measurement. 3.3 V max!
9	AC_Current	Input	Analog input for AC current measurement. 3.3 V max!
10	AGND	Power output	Analog ground. Do not connect on the board to digital ground!
11	AC_Relay_Vtg	Input	Analog input for AC relay supply voltage. 3.3 V max!
12	DC_Input_Vtg	Input	Analog input for DC input voltage. 3.3 V max!
13	AGND	Power output	Analog ground. Do not connect on the board to digital ground!
14	DC_Current	Input	Analog input for DC current measurement. 3.3 V max!
15	AC_Inverter_Vtg	Input	Analog input internal AC voltage measurement before the grid relays. 3.3 V max!
16	AGND	Power output	Analog ground. Do not connect on the board to digital ground!
17	LED_Ctrl_Red	Output	Digital output for controlling a LED. 3.3 V, 4 mA max!
18	LED_Ctrl_Green	Output	Digital output for controlling a LED. 3.3 V, 4 mA max!
19	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
20	+3V3	Power input	Power input for 3.3 V supply voltage.
21	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
22	UART_RX	Input	UART input. 3.3 V max! May be used as digital input
23	UART_TX	Output	UART output. 3.3 V, 4 mA max! May be used as digital output
24	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
25	I2C_Dat	Bidirectional	I²C data line. 3.3 V, 4 mA max! On the module connected to a temperature sensor.
26	I2C_Clk	Output	I²C clock line. 3.3 V, 4 mA max! On the module connected to a temperature sensor.
27	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
28	PWM_Highside	Output	Digital output. Provides the PWM for driving the high side power supply. 3.3 V, 4 mA max!
29	Boost_T1	Output	Digital output. Provides the PWM for the DC booster circuit. 3.3 V, 4 mA max!
30	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
31	Relay_Vtg_Ctrl	Output	Digital output. Provides the PWM for controlling the grid relay supply voltage. 3.3 V, 4 mA max!
32	Bridge_T1	Output	Digital output. Provides the PWM for controlling V1 (high side 1) of the H4 inverter bridge. 3.3 V, 4 mA max!
33	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
34	Bridge_T2	Output	Digital output. Provides the PWM for controlling V2 (low side 1) of the H4 inverter bridge. 3.3 V, 4 mA max!
35	Bridge_T3	Output	Digital output. Provides the PWM for controlling V3 (high side 2) of the H4 inverter bridge. 3.3 V, 4 mA max!
36	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
37	Bridge_T4	Output	Digital output. Provides the PWM for controlling V4 (low side 2) of the H4 inverter bridge. 3.3 V, 4 mA max!
38	Inv_Relay_Ctrl	Output	Digital output. Switches the inverter-side grid relay. 3.3 V, 4 mA max!
39	GND	Power input	Digital ground. This is provided from the power supply of the main PCB.
40	Grid_Relay_Ctrl	Output	Digital output. Switches the grid-side grid relay. 3.3 V, 4 mA max!
41	GND	Power output	Digital ground. This is provided from the power supply of the main PCB.

Controller Pin Assignment

Pin	Signal/Description
1	+3V3 supply voltage
2	❌ not connected
3	❌ not connected
4	❌ not connected
5	10 MHz osc in
6	10 MHz osc out
7	Reset input
8	⏚ Analog ground
9	+2.5 V reference voltage input
10	❌ not connected
11	Analog input: AC grid voltage
12	Analog input: Relay control voltage
13	Analog input: DC link voltage
14	Analog input: AC current
15	Analog input: AC relay voltage
16	Analog input: DC input voltage
17	Analog input: DC current
18	Analog input: AC inverter voltage
19	Pull up to +3V3 (reserve)
20	LED control (red)
21	Booster control (PWM)
22	Relay voltage control (PWM)
23	⟂ Ground
24	+3V3 supply voltage
25	❌ not connected
26	I²C clock (temperature sensor reading)
27	I²C2 data (temperature sensor reading)
28	❌ not connected
29	Inverter bridge T1 control (PWM)
30	Inverter bridge T2 control (PWM)
31	Inverter bridge T3 control (PWM)
32	Inverter bridge T4 control (PWM)
33	Status LED1
34	Serial programming interface SWDIO
35	⟂ Ground
36	+3V3 supply voltage
37	Serial programming interface SWCLK
38	Status LED2
39	PWM for High Side supply of inverter bridge
40	LED control (green)
41	Inverter relay control
42	UART1 TX for connection to communication module
43	UART1 RX for connection to communication module
44	BOOT0 pin input, pull-up
45	Grid relay control
46	❌ not connected
47	⟂ Ground
48	+3V3 supply voltage