eBUS is a serial 2-wire serial data-bus, often used in heating, solar energy, and other building automation systems. This project provides an interface to access an eBUS via USB. It uses a series transistor regulator circuit with a low IZT zener diode to extract the operating voltage from the eBUS, an ADuM1201 for the galvanic isolation, and a STM32 microcontroller for the UART to USB conversion. Power consumption on the eBUS side is between 475uA (eBUS low/8V) and 750uA (eBUS idle high/24V), making the interface qualify as a class 0 device with respect to the eBUS specification. It has been designed to fit into an CNMB/1/2 1TE DIN rail enclosure by CAMDENBOSS. The interface is intended to be used with ebusd. Note that the firmware is currently just a proof-of-concept and only implements a basic uart to USB bridge. Support for the ebusd enhanced protocol is planned for the near future.
When ordering at JLCPCB, remove the mouse bites and cut the boards yourself. Otherwise JLCPCB will charge you for two designs.
| Designator | Footprint | Quantity | Value | LCSC Part # |
|---|---|---|---|---|
| C1, C2, C7 | C0805 | 3 | 10u | C15850 |
| C10, C3, C4, C5, C6, C8, C9 | C0603 | 7 | 100n | C14663 |
| C11, C12 | C0805 | 2 | 1u | C28323 |
| D1, D2, D4 | SOT-23-3 | 3 | BAV99 | C2500 |
| D3 | SOD-123 | 1 | 5V6, Onsemi MMSZ4690* | C152307 |
| D5 | SOD-123 | 1 | 24V/1W, KDZVTR24B, MM1W24 | C209605, C438336 |
| D6 | SOD-123 | 1 | 7V5/1W, KDZVTR7.5B, MM1W7V5 | C209594, C382950 |
| D7 | LED_0603 | 1 | LED | C72043 |
| D8, D9, D10 | D3.0mm | 3 | 3mm LED | CHANZON 3mm diffused LED |
| J1 | MSTBA_2,5_2-G-5,08 | 1 | MSTBA 2,5/2-G-5,08 | C3697 |
| J2, J6 | Molex_PicoBlade_53047-0210 | 2 | Molex 53047-0210 | C114130 |
| J3, J7 | Molex_PicoBlade_53047-0410 | 2 | Molex 53047-0410 | C504989 |
| J4 | TC2030-NL | 1 | Tag-Connect 6-Pin "No Legs" TC2030-NL Plug-of-Nails | TC2030-CTX-NL-STDC14 |
| J5 | HRO_TYPE-C-31-M-12 | 1 | HRO TYPE-C-31-M-12 | C165948 |
| J8 | PinHeader_1x02_P1.27mm | 1 | Harwin M50-3530242 | C2881948 |
| Q1, Q2 | SOT-23-3 | 2 | BC817-40, S9013J3 | C52801, C6749 |
| R1, R2, R3 | R0603 | 3 | 100K | C25803 |
| R10 | R0603 | 1 | 47K | C25819 |
| R12, R13 | R0603 | 2 | 5K1 | C23186 |
| R14 | R0805 | 1 | 100K | C149504 |
| R15, R16 | R0805 | 2 | 15K | C17475 |
| R4 | R0603 | 1 | 4K7 | C23162 |
| R5 | R0603 | 1 | 300K | C23024 |
| R6 | R0603 | 1 | 51K | C23196 |
| R7 | R0603 | 1 | 2M | C22976 |
| R8 | R0603 | 1 | 10K | C25804 |
| R9 | R0603 | 1 | 0R | C21189 |
| U1 | SO08 | 1 | AZV3002, TSX3702 | C5123396, C2970396 |
| U2 | SO08 | 1 | ADuM1201, π122U31 | C9669, C471590 |
| U5 | SOT-23-6L | 1 | SRV05-4 | C85364 |
| U6 | SOT-23-3 | 1 | XC6206P332MR | C5446 |
| U7 | LQFP-32 | 1 | STM32L412KBT6, STM32F042K6T6 | C529438, C69216 |
* Low IZT of 50uA is required. Other manufacturers than Onsemi may not qualify. For example, MMSZ4690 from Jiangsu Changjing Elec. Tech. is not recommened.