DescriptionOverviewThis is a 2-channel isolated RS485 expansion HAT designed for Raspberry Pi, adopts the SC16IS752 SP3485 solution, with embedded protection circuits such as power supply isolation, ADI magnetical isolation, and TVS diode, etc.It is easy to control the 2-channel RS485 for auto transceiving via SPI interface. Due to its fast communication, stability, reliability, and safety, it is an ideal choice for fields like industrial automation.FeaturesStandard Raspberry Pi 40PIN GPIO extension header, supports Raspberry Pi series boardsAdopts SC16IS752 SP3485 dual chip combination, converts SPI to RS485, data rate up to 921600bpsAllows transceiving data manually or automatically, configured by DIP switchOnboard TVS (Transient Voltage Suppressor), effectively suppress surge voltage and transient spike voltage in the circuit, lightningproof & anti-electrostaticOnboard auto-recovery fuse and protection diodes, ensures the current/voltage stable outputs, provides over-current/over-voltage proof, improves shock resistanceOnboard LEDs for indicating the power and transceiver statusBreakout SPI control pins, for connecting with host control boards like ArduinoComes with development resources and manual (examples in C and Python)SpecificationsUART expansion chip: SC16IS752RS485 transceiver: SP3485Communication interface: SPIData rate: 300 ~ 921600 bpsOperating voltage: 3.3V / 5VDimensions: 65mm × 56.5mmMounting hole size: 3.0mmWhat’s on BoardSC16IS752 UART expansion chipADUM1412 digital isolatorPC817 optocouplerSP3485 RS485 transceiverB0505LS power supply isolation moduleRT9193-33 power chipSMAJ12CA transient suppress diode arrayAuto-recovery fuseStatus indicator PWR: power indicator RXD/TXD: UART transceiving indicatorRaspberry Pi GPIO connector: for connecting Raspberry PiRS485 terminalMCU control header: for connecting host control boards like Arduino120Ω terminal resistor switchInterrupt pin switchOperating mode selection Half-auto: A=0, B=1 Full-auto: A=1, B=0ExamplePinoutsPINRASPBERRY PI (BCM)DESCRIPTIONVCC5V3.3V/5V power supplyGNDGNDGroundSCKP21 (SPI1 SCLK)SPI clock inputMOSIP20 (SPI1 MOSI)SPI data inputMISOP19 (SPI1 MISO)SPI data outputCSP18 (SPI1 CS)SPI chip selectIRQP24Interrupt outputEN1P27Channel 1 TX/RX enable: high for TX, low for RXEN2P22Channel 2 TX/RX enable: high for TX, low for RXDimensionDevelopment ResourcesWiki : www.waveshare.com/wiki/2-CH_RS485_HAT
