Welcome to eBUS Adapter 3!

This is the documentation of the eBUS adapter, which can be used to communicate with an eBUS enabled heating, ventilation or solar system.

Introduction

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:

In order to be able to get all these options on a 5cm x 5cm board, almost only SMD is used:

schema

The SMD technology also offers some advantages:

Two of the variants also offer the option of connecting sensors and/or displays.

Connections

This is an overview of the individual components and their connections: schema

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.

USB

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.

Raspberry Pi

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

Details on setting up the Raspberry Pi can be found here.

WIFI

WIFI
By plugging a LOLIN/Wemos D1 mini with ESP-8266 onto socket J9, the adapter can be used via WLAN. 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.

Ethernet

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.

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”).

Circuit diagram

circuit

Connection of sensors, actuators or displays

In the variants with Wemos and Raspberry Pi, the following pin headers are available for connecting additional components:

Further connections

PIC programming connector J11

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.

PIC connector J12

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.:
2 power

Usage

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.

Simultaneous use of USB for ebusd and Wemos for sensors

[TODO Testen]
The jumpers have to be set as follows:

The power is supplied directly via the USB connector J2 on the adapter and RX/TX of the Wemos and its USB serial cannot be used (on RX eBUS traffic comes in).

Attention: Always connect only one power supply, i.e. a maximum of one connection of:

Overview of jumpers/pin headers, functions

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:

jumper

LEDs

The adapter has 4 LEDs with the following assignment:

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: