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This is the documentation of the eBUS adapter, which can be used to communicate with an eBUS enabled heating, ventilation or solar system.
You can reserve such an adapter here and it will then be sent in sequence as soon as the next batch is available.
Version 3 of the eBUS adapter fulfils the arbitration times required by the eBUS specification for the first time.
This is made possible by the use of a PIC which, among other things, brings the following advantages:
- minimal time delay due to hardware-related programming
- flexible, configurable variants for connecting to the host:
- USB{:.usb} serial via CP2102 (onboard)
- Raspberry Pi{:.rpi} via GPIO/ttyAMA0
- WIFI{:.wifi} via LOLIN/Wemos D1 mini with ESP-8266
- Ethernet{:.ethernet} via USR-ES1 module with W5500
- full support for ebusd enhanced protocol and standard protocol
- updatable firmware using a serial bootloader
In order to be able to get all these options on a 5cm x 5cm board, almost only SMD is used:
The SMD technology also offers some advantages:
- high packing density
- all variants on one board
- CP2102 plug-in module no longer required
- cheap equipment
Two of the variants also offer the option of connecting sensors and/or displays.
This is an overview of the individual components and their connections:
- Heating system
is connected to the adapter via a 2-wire cable. - Adapter
connected to ebusd either via- USB (UART),
- GPIO (UART) of the Raspberry Pi,
- WIFI (Wemos) or
- LAN (USR-ES1 module with W5500).
- ebusd
interprets the eBUS protocol and provides the data bidirectionally via TCP, HTTP, MQTT and KNX for FHEM, Home-Assistant, Node-Red, and others.
{:id="variants"} USB support is built into all variants, as the CP2102 is always installed directly on the board. This is necessary, to e.g. update the PIC firmware or to adjust the Ethernet configuration.
The desired variant can be configured via jumpers.
The protocol between ebusd and the adapter is either the eBUS protocol directly ("standard protocol") or the ebusd "enhanced protocol". The enhanced protocol uses all advantages of the adapter by handling the eBUS arbitration directly from the PIC firmware.
Note for high-speed enhanced mode:
{:id="ens"}
For the enhanced protocol, a high-speed variant may be used for serial connections (USB, RPI and WIFI) that avoids
unnecessary delays due to the transfer of data from/to ebusd (or ESP).
This can be activated by setting a jumper on J12.
The ebusd device configuration then needs to be changed from enh: prefix to ens: prefix for direct serial
connections (i.e. USB or RPI).
For WIFI, the ESP firmware needs to be configured accordingly and the ebusd device configuration remains at enh:.
{:.usb}
To use the adapter via USB port J2, the jumpers have to be set as follows:
The power is supplied directly via the USB connector J2 on the adapter.
The ebusd device configuration is e.g. -d enh:/dev/ttyUSB0, where ttyUSB0 might be different when several USB serial
devices are connected.
For high-speed enhanced mode, see the hint above.
{:.rpi id="rpi"}
Using the 2x13 socket J8, the adapter can be plugged onto the Raspberry Pi directly.
The jumpers have to be set as follows:
The power is supplied directly via the Raspberry Pi socket J8.
The ebusd device configuration is: -d enh:/dev/ttyAMA0 --latency=50
For high-speed enhanced mode, see the hint above.
Details on setting up the Raspberry Pi can be found here.
{:.wifi}
By plugging a LOLIN/Wemos D1 mini with ESP-8266 onto socket J9,
the adapter can be used via WIFI.
The jumpers have to be set as follows:
The power is supplied directly via the USB connector of the Wemos.
Attention: The Wemos are incredibly delicate with regard to the power supply! A variety of effects come up when the power supply is insufficient, e.g. reboots, or no connection at all, or only poor and unstable connection to the Access Point.
The Wemos has to be flashed with a suitable firmware, e.g. ebusd-esp (starting from version 22.11.2020). ebusd-esp then has to be configured to "Adapter 3 RX+TX".
The ebusd device configuration is e.g. -d enh:192.168.178.2:9999, where 192.168.178.2 has to be replaced with the
right IP address (ebusd enhanced high-speed mode is not valid for network traffic).
For high-speed enhanced mode as transfer between the adapter and ebusd-esp, see the hint above.
{:.ethernet}
By plugging a USR-ES1 modul with W5500 onto socket J10,
the adapter can be used via LAN.
The jumpers have to be set as follows:
The power is supplied directly via the USB connector J2 on the adapter.
The Ethernet configuration (IP address, network mask, gateway) is done via the bootloader in the PIC through the USB port J2, see here: Ethernet configuration.
The ebusd device configuration is e.g. -d enh:192.168.178.2:9999, where 192.168.178.2 has to be replaced with the
right IP address (ebusd enhanced high-speed mode is not valid for network traffic).
The PIC firmware sets the MAC address of the adapter in the LAN to AE:B0:53:XX:XX:XX, where the "XX" depend on the ID of
the PIC (AEB053 stands for "Adapter eBUS 3").
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In the variants with Wemos and Raspberry Pi, the following pin headers are available for connecting additional components:
- J3: Gas sensor or switch
- J5: I2C, e.g. OLED SSD1306 or Nextion
- J6:
- with Raspberry Pi: I2C as stated above (Pins 1-4)
- with Wemos: I2C (Pins 1-4) and additionally Wemos D0 (Pin 5) and A0 (Pin 6)
- J7: 1wire, e.g. for temperature sensor DS18B20
The PIC programming connector J11 allows exchanging the Firmware of the PIC as well as the bootloader with an appropriate programming device. This should only be necessary in rare cases, as the PIC was programmed before delivery and the adapter can therefore be used immediately. For more details, see PIC Firmware.
This connector holds pins of the PIC and their assignment and usage depends on the PIC firmware, see PIC Firmware.
Important note: The pins on J12 must never be connected to any pin on the other jumpers/pin headers/sockets as separate power sources are used here. Any connection endangers the adapter and devices on the eBUS!
Here is a picture showing the two isolated halves of the board: red for eBUS and green for USB etc.:
In addition to the adapter, software is required that interprets and evaluates the eBUS traffic. This is done for example by ebusd, which can also be installed on a Raspberry Pi.
{:id="jumper"}
| Connector | Function | USB | Raspberry Pi | WIFI | Ethernet |
|---|---|---|---|---|---|
| J1 | Jumper TX | USB | RPI | RPI | RPI |
| J2 | USB connector | USB connector | - | - | power connector |
| J3 | Gas sensor | - | Gas sensor | Gas sensor | - |
| J4 | Jumper POWER | USB | RPI | (RPI) | USB |
| J5 | I2C | - | I2C | (I2C)* | - |
| J6 | I2C | - | I2C | (I2C)*+ext | - |
| J7 | 1wire sensor | - | 1wire sensor | 1wire sensor | - |
| J8 | RPi GPIO connector | - | Raspberry Pi | - | - |
| J9 | Wemos connector | - | - | Wemos D1 mini | - |
| J10 | USR-ES1 connector | - | - | - | USR-ES1 W5500 |
| J11 | PIC PROG | - | - | - | - |
| J12 | PIC AUX | PIC Jumper | PIC Jumper | PIC Jumper: 4-5 | PIC Jumper: 5-6 |
| J13/J14 | eBUS connector | eBUS | eBUS | eBUS | eBUS |
* To the points in brackets:
- I2C is currently not yet supported by the ebusd-esp firmware.
- with WIFI, J4 can be left out or set to RPI.
The adapter has 4 LEDs with the following assignment:
- yellow: power supply PIC
- blue: signals from PIC
- green: eBUS receive
- red: eBUS send
The PIC is only supplied with power and can work at all when the yellow LED lights up. The green and red LEDs light up on the corresponding eBUS traffic and the green one lights up permanently if the eBUS line is not yet connected or the voltage level on the eBUS line is too low. The blue LED is controlled by the PIC firmware, which is described here.
Here are some links that contribute to the topic or contain basic information, some of which are in German only:
- eBUS spezification (physikal layer OSI 1)
- wiki about board V 1.6
- documentation for Adapter V 2.0-2.2
- Reichelt cart for pin headers/connectors:
- the short pin headers and jumpers are for J1, J4, J11 and J12 (1x6 to be split into 2 pieces of 1x3 each, 1x14 to be split into 1x8 + 1x6)
- the 1x6 female headers are for J10
- the long pin headers are for J3, J5, J6 and J7
- ebusd-esp firmware for Wemos D1
- ebusd wiki