🫐 Circuit Diagram · Raspberry Pi 4

SmartMill Guardian β€” Full Circuit Schematic

Raspberry Pi 4B Β· ADXL345 Β· MLX90614 Β· MAX485 RS-485 Β· 4-Ch Relay HAT Β· DS3231 RTC Β· Industrial Power Supply

3.3V / 5V Power
GND
SPI Bus (ADXL345)
IΒ²C Bus (MLX90614, DS3231)
UART / RS-485
GPIO (Relay, INT)
RASPBERRY PI 4B ARM Cortex-A72 Β· 4GB RAM BCM2711 Broadcom SoC 1.8GHz Β· 4-core GPIO HEADER (40-pin) Ethernet USB3 5V USB-C WiFi/BT BCM43455 MicroSD ADXL345 3-Axis Accelerometer Β· SPI ADXL345BCCZ Β±16g Β· 13-bit LGA-14 package VCC GND SCK SDI SDO CS INT1 INT2 MLX90614 IR Temp Sensor Β· IΒ²C 0x5A IR lens VCC(3.3V) GND SDA SCL PWM/OD MAX485 RS-485 Transceiver Β· UART MAX485CSA DIP-8 Β· 2.5Mbps Half-Duplex RO (RX) RE DE DI (TX) VCC GND A (D+) B (Dβˆ’) 4-CH RELAY HAT GPIO 17/27/22/5 Β· 250VAC/10A RL1 RL2 RL3 RL4 SPINDLE COOLANT ALARM AUX Contacts: NC / NO / COM Β· 250VAC 10A DS3231 RTC IΒ²C 0x68 Β· Β±2ppm TCXO CR2032 SDA SCL VCC GND SQW/INT 32kHz INDUSTRIAL PSU Mean Well HDR-15-5 24V DC INPUT 24V / 1A from DIN PSU 5V OUTPUT β†’ RPi USB-C 3.3V LDO β†’ Sensors AMS1117-3.3 C1:100Β΅F, C2:100nF SIEMENS S7-1200 PLC Β· Modbus RTU Slave Slave ID: 0x01 Reg 0x64: spindle_rpm Reg 0x65: motor_mA Reg 0x66: coolant_Β°C Baud: 9600 Β· 8N1 A(+) ──── D+ line B(βˆ’) ──── Dβˆ’ line [EXISTING] SCLK(GPIO11) MOSI MISO CS(GPIO8) INT1β†’GPIO25 SDA(GPIO2) SDA(GPIO2) SCL(GPIO3) SCL(GPIO3) UART TX(GPIO14) RX(GPIO15) DE/REβ†’GPIO18 RS-485 A(D+) RS-485 B(Dβˆ’) RT: 120Ξ© GPIO17/27/22/5 5V POWER RAIL 3.3V SENSOR RAIL GND (Common) 4.7kΞ© pull-ups ☁️ AWS IoT Core MQTT/TLS Β· Port 8883 InfluxDB Β· Grafana Β΅Tensor alerts WiFi Β· MQTT/TLS 8883 SmartMill Guardian β€” Raspberry Pi 4 Circuit Schematic Β· madhav.dev

🫐 RPi 4B GPIO β€” ADXL345 (SPI0)

RPi GPIORPi PinADXL345 PinWire
GPIO8 (CE0)24CSSPI CS
GPIO9 (MISO)21SDO/ALTSPI MISO
GPIO10 (MOSI)19SDI/SDASPI MOSI
GPIO11 (SCLK)23SCL/SCLKSPI SCLK
GPIO2522INT1Interrupt
3V31VCCPower
GND6GNDGround

🌑️ RPi 4B GPIO β€” MLX90614 (IΒ²C1)

RPi GPIORPi PinMLX90614 PinWire
GPIO2 (SDA1)3SDAIΒ²C SDA
GPIO3 (SCL1)5SCLIΒ²C SCL
3V31VCCPower
GND6GNDGround
4.7kΞ© pull-ups on SDA & SCL

πŸ“‘ RPi 4B GPIO β€” MAX485 (UART0)

RPi GPIORPi PinMAX485 PinWire
GPIO14 (TXD0)8DI (pin 4)UART TX
GPIO15 (RXD0)10RO (pin 1)UART RX
GPIO1812DE+RE (pin 2,3)Direction
5V2VCC (pin 8)Power
GND6GND (pin 5)Ground
A/B terminals β†’ Siemens S7 RS-485 port Β· 120Ξ© termination

⚑ RPi 4B GPIO β€” Relay HAT

RPi GPIORPi PinRelayFunction
GPIO1711RL1Spindle Stop
GPIO2713RL2Coolant Stop
GPIO2215RL3Alarm Siren
GPIO529RL4Aux / Lamp
Relay HAT stacks on 40-pin GPIO header Β· NO/NC/COM contacts

πŸ• RPi 4B GPIO β€” DS3231 RTC (IΒ²C1)

RPi GPIORPi PinDS3231 PinWire
GPIO2 (SDA1)3SDAIΒ²C SDA (shared)
GPIO3 (SCL1)5SCLIΒ²C SCL (shared)
GPIO47SQW/INT1Hz INT
3V31VCCPower
IΒ²C addr: 0x68 Β· CR2032 backup battery Β· EEPROM: 0x57

βš™οΈ Bill of Materials (Key Components)

ComponentQtyNotes
Raspberry Pi 4B 4GB1Main controller
ADXL345 Module1SPI accelerometer
MLX906141IR temp, TO-39
MAX485CSA1RS-485 driver
DS3231 Module1RTC + EEPROM
4-Ch Relay HAT1GPIO controlled
Mean Well HDR-15-51DIN rail PSU
AMS1117-3.313.3V LDO
120Ξ© Resistor1RS-485 termination
4.7kΞ© Resistor2IΒ²C pull-ups