# ESP32 RS485 (Modbus) Controller Reference Design ## Description This project is a controller module that uses the ESP32-WROOM-32E and the MAX3485 to communicate with Modbus devices. It has a USB-C port for power and data, a voltage regulator for stable operation, and headers for connecting sensors and actuators. It also has a CH340C chip for USB to serial conversion. #referenceDesign #project #ESP32 #ESP32WROOM #RF #WIFI #MCU #referenceDesign #simple-embedded #espressif #template #MAX3485 #RS485 #maximintegrated #reference-design #polygon ## Project Details - **Owner:** vasy_skral - **Created:** 1/25/2024 - **Last Updated:** 3/6/2026 - **Visibility:** Public - **License:** https://creativecommons.org/licenses/by/4.0/ - **Stars:** 3 - **Forks:** 2 - **Copies:** 20 ## Key Components ### A RS485 B — [2-Position Screw Terminal](https://www.flux.ai/corynrobinson/2-position-screw-terminal~s4.md) - Manufacturer Name: Würth Elektrik - Manufacturer Part Number: 691137710002 - Datasheet URL: https://www.we-online.com/katalog/datasheet/691137710002.pdf - Part Type: Connector **Pins:** - P1 [pin 1] - P2 [pin 2] ### BOOT — [TL3330AF260QG](https://www.flux.ai/vasy_skral/tl3330af260qg~g8.md) - Part Type: Switch - Manufacturer Name: E-Switch - Manufacturer Part Number: TL3330AF260QG - Datasheet URL: https://sten-eswitch-13110800-production.s3.amazonaws.com/system/asset/product_line/data_sheet/163/TL3330.pdf **Pins:** - P1 [pin 1] - P2 [pin 2] ### D1 — [1N5819HW-7-F](https://www.flux.ai/jecstronic/1n5819hw-7-f~x5v.md) - Part Type: Diode - Manufacturer Name: Diodes Incorporated - Datasheet URL: https://www.diodes.com/assets/Datasheets/ds30217.pdf - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: 1N5819HW-7-F **Pins:** - A [pin 2] - K [pin 1] ### D2 — [WE-TVS-82400102](https://www.flux.ai/vasy_skral/we-tvs-82400102~xt.md) - Manufacturer Part Number: 82400102 - Datasheet URL: https://katalog.we-online.de/pbs/datasheet/82400102.pdf - Part Type: Protection - Manufacturer Name: Würth Elektronik - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - GND [pin 2] - IO1 [pin 6] - IO1 [pin 1] - IO2 [pin 4] - IO2 [pin 3] - VDD [pin 5] ### D3 — [SM712](https://www.flux.ai/jecstronic/sm712~90.md) - License: https://creativecommons.org/licenses/by/4.0/ - Manufacturer Part Number: SM712 - Manufacturer Name: MDD - Datasheet URL: https://media.digikey.com/pdf/Data%20Sheets/NextGen%20Components%20PDFs/SOT23SM712S712.pdf - Part Type: Diode **Pins:** - A1 [pin 1] - A2 [pin 2] - common [pin 3] ### IC1 — [CH340C](https://www.flux.ai/vasyl/ch340c~qf3.md) - Datasheet URL: https://datasheet.lcsc.com/szlcsc/Jiangsu-Qin-Heng-CH340C_C84681.pdf - Manufacturer Part Number: CH340C - Part Type: Integrated Circuit - Manufacturer Name: Wah **Pins:** - ~CTS [pin 9] - ~DCD [pin 12] - ~DSR [pin 10] - ~DTR [pin 13] - ~RI [pin 11] - ~RTS [pin 14] - GND [pin 1] - NC [pin 7] - NC [pin 8] - R232 [pin 15] - RXD [pin 3] - TXD [pin 2] - UD- [pin 6] - UD+ [pin 5] - V3 [pin 4] - VCC [pin 16] ### IC3 — [MAX3485CSA+](https://www.flux.ai/vasyl/max3485csaplus~o8n.md) - Manufacturer Part Number: MAX3485CSA+ - Manufacturer Name: Maxim Integrated - Datasheet URL: https://datasheets.maximintegrated.com/en/ds/MAX3483-MAX3491.pdf - Part Type: Integrated Circuit **Pins:** - ~RE [pin 2] - A [pin 6] - B [pin 7] - DE [pin 3] - DI [pin 4] - GND [pin 5] - RO [pin 1] - VCC [pin 8] ### J1 — [Pin Header 01x16 2.54mm Vertical](https://www.flux.ai/vasy_skral/pin-header-01x16-2p54mm-vertical~1qc.md) - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: Connector **Pins:** - Pin_1 [pin 1] - Pin_10 [pin 10] - Pin_11 [pin 11] - Pin_12 [pin 12] - Pin_13 [pin 13] - Pin_14 [pin 14] - Pin_15 [pin 15] - Pin_16 [pin 16] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] - Pin_5 [pin 5] - Pin_6 [pin 6] - Pin_7 [pin 7] - Pin_8 [pin 8] - Pin_9 [pin 9] ### J2 — [Pin Header 01x16 2.54mm Vertical](https://www.flux.ai/vasy_skral/pin-header-01x16-2p54mm-vertical~1qc.md) - Part Type: Connector - License: https://creativecommons.org/licenses/by/4.0/ **Pins:** - Pin_1 [pin 1] - Pin_10 [pin 10] - Pin_11 [pin 11] - Pin_12 [pin 12] - Pin_13 [pin 13] - Pin_14 [pin 14] - Pin_15 [pin 15] - Pin_16 [pin 16] - Pin_2 [pin 2] - Pin_3 [pin 3] - Pin_4 [pin 4] - Pin_5 [pin 5] - Pin_6 [pin 6] - Pin_7 [pin 7] - Pin_8 [pin 8] - Pin_9 [pin 9] ### PWR — [LED-0805-Template-2](https://www.flux.ai/vasy_skral/led-0805-template-2~uu0.md) - License: https://creativecommons.org/licenses/by/4.0/ - Part Type: LED **Pins:** - A [pin 2] - K [pin 1] ### Q1 — BSS138 - Part Type: Transistor - Manufacturer Part Number: BSS138 - Datasheet URL: https://www.onsemi.com/pdf/datasheet/bss138-d.pdf - Manufacturer Name: onsemi **Pins:** - D - G - S ### Q2 — BSS138 - Datasheet URL: https://www.onsemi.com/pdf/datasheet/bss138-d.pdf - Manufacturer Name: onsemi - Part Type: Transistor - Manufacturer Part Number: BSS138 **Pins:** - D - G - S ### RST — [TL3330AF260QG](https://www.flux.ai/vasy_skral/tl3330af260qg~g8.md) - Manufacturer Name: E-Switch - Part Type: Switch - Datasheet URL: https://sten-eswitch-13110800-production.s3.amazonaws.com/system/asset/product_line/data_sheet/163/TL3330.pdf - Manufacturer Part Number: TL3330AF260QG **Pins:** - P1 [pin 1] - P2 [pin 2] ### U1 — [AMS1117-3.3](https://www.flux.ai/vasy_skral/ams1117-33~34.md) - Part Type: Integrated Circuit - Manufacturer Part Number: AMS1117-3.3 - Manufacturer Name: AMS - Datasheet URL: https://datasheet.lcsc.com/lcsc/1811021917_Advanced-Monolithic-Systems-AMS1117_C6188.pdf **Pins:** - GND [pin 1] - TAB(VOUT) [pin 4] - VIN [pin 3] - VOUT [pin 2] ### U2 — [ESP32-WROOM-32E](https://www.flux.ai/vasy_skral/esp32-wroom-32e~7ed.md) - Manufacturer Part Number: ESP32-WROOM-32E - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32e_esp32-wroom-32ue_datasheet_en.pdf - Part Type: Integrated Circuit - Manufacturer Name: Espressif Systems **Pins:** - GND=> . [pin 15] - EN [pin 3] - GND [pin 38] - GND [pin 39] - GND [pin 1] - IO0 [pin 25] - IO12 [pin 14] - IO13 [pin 16] - IO14 [pin 13] - IO15 [pin 23] - IO16 [pin 27] - IO17 [pin 28] - IO18 [pin 30] - IO19 [pin 31] - IO2 [pin 24] - IO21 [pin 33] - IO22 [pin 36] - IO23 [pin 37] - IO25 [pin 10] - IO26 [pin 11] - IO27 [pin 12] - IO32 [pin 8] - IO33 [pin 9] - IO34 [pin 6] - IO35 [pin 7] - IO4 [pin 26] - IO5 [pin 29] - NC [pin 18] - NC [pin 19] - NC [pin 17] - NC [pin 21] - NC [pin 22] - NC [pin 32] - NC [pin 20] - RXD0/IO3 [pin 34] - SENSOR_VN [pin 5] - SENSOR_VP [pin 4] - TXD0/IO1 [pin 35] - VDD [pin 2] ### USB1 — [TYPE-C-31-M-12](https://www.flux.ai/vasy_skral/type-c-31-m-12~75f.md) - Part Type: Connector - Datasheet URL: https://datasheet.lcsc.com/lcsc/2205251630_Korean-Hroparts-Elec-TYPE-C-31-M-12_C165948.pdf - Manufacturer Part Number: TYPE-C-31-M-12 - Manufacturer Name: Korean Hroparts Elec **Pins:** - CC1 [pin A5] - CC2 [pin B5] - DN1 [pin A7] - DN2 [pin B7] - DP1 [pin A6] - DP2 [pin B6] - GND [pin B1A12] - GND [pin A1B12] - SBU1 [pin A8] - SBU2 [pin B8] - SHIELD [pin S3] - SHIELD [pin S1] - SHIELD [pin S4] - SHIELD [pin S2] - VBUS [pin A4B9] - VBUS [pin B4A9] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/vasy_skral/esp32-rs485-modbus-controller-reference-design~cko](https://www.flux.ai/vasy_skral/esp32-rs485-modbus-controller-reference-design~cko).* --- *Generated from [https://www.flux.ai/vasy_skral/esp32-rs485-modbus-controller-reference-design~cko](https://www.flux.ai/vasy_skral/esp32-rs485-modbus-controller-reference-design~cko)*