The document describes the concept design of a control system that receives input signals from sensors and buttons and controls actuators. It includes: - A main microcontroller (STM32F103C8T6) that communicates using Modbus, SPI, UART protocols and has analog and digital input/output channels. - Isolated analog and digital input/output modules using optocouplers and isolation ICs to interface between sensors/actuators and the microcontroller. - Communication options including Ethernet using an ENC28J60 module, WiFi using an ESP8266 module, and RS-485/RS-232 using MAX485 and MAX232 ICs. - A power supply

1. Group 17
Vũ Thị Thùy Linh
An Thị Thúy
Lê Ngọc Khôi
Ngô Tiến Công
1. Concept design
Function: Receive the input signal from sensors, buttons,.. and control the actuators
Power supply: 24VDC from adapter, 5VDC, 3V3DC
Main MCU: STM32F103C8T6
Input: 8 DI, 2 AI. Can be extended.
Output: 8 DO, 2AO. “Source” type, using 24VDC relay to switch.
DI DO are isolated.
Communication protocol: Modbus RTU (RS232, RS485), SPI (Ethernet), UART (Wifi)
2. Block diagram
3. Component
3.1. MCU

2. STM32F103C8T6 has:
- LQFP-48 footprint package
- 37 I/O
- Operating temperature: −400
𝐶 to 850
𝐶
- Interface Type: CAN, I2C, SPI, USART, USB
- 3V3DC power supply
3.2. Analog IO
- Use SPI isolator IC LTM2983 to isolated between AI and MCU.
- LTM2985 to isolated between AO and MCU.
- 16 bits external ADC LTC2642-16 is used to convert analog signal from sensors.
- 16 bits external DAC LTC2378-18 is used to convert digital signal from MCU.
- 0-5VDC analog input
3.3. Digital IO
- Use opto PC817 to isolate

3. - Power supply: 3V3
- Output module has 1 IC buffer ULN2803.
- IO can be extended by using IC Shift Registers 74HC595 and 74HC165.
- Switch by relay 24VDC
3.4. Ethernet
- Use IC ENC28J60 Ethernet, with SOP-28 footprint package
- SPI interface
- RJ45 cable connector HR911105A
- Power supply: 3V3DC
3.5. Wifi
Module wifi ESP8266-01:
- Power Supply: +3.3V only
- Current Consumption: 100mA
- TCP/IP protocol
3.6. RS485 + RS232
RS485:
- MAX485
- DB9 cable connector
- 5V power supply
- Half duplex connect
RS232:
- MAX232
- DB9 cable connector

4. - 5V power supply
3.7. Power supply
- 24VDC is taken from adapter
- DC – DC Converter 24VDC - 5VDC: Step Down Module LM2576 – 5V
- DC – DC Converter 5VDC – 3V3DC: Linear Voltage Regulator LM1117 – 3.3V