ELV RSU Modification (FS20 to ESP8266)
This page decribes the ELV RSU devices modification using an ESP8266 ESP-12 module and Sonoff Tasmota firmware.
If you are looking for original documention, go to Sonoff Tasmota Wiki.
Modification of the roller shutter controls ELV RSU (FS20) to WLAN (using ESP8266 ESP-12 module) operation under Sonoff Tasmota.
Since both μController (original RSU ATMega and the new ESP8266) are operating with 3.3V and there is already a 3.3V regulator on RSU board no changes need to be made to the power supply. The tap of the supply voltage for the ESP-12 is done via the supply voltage pins of the 868MHz transmitter module. We remove both, the origina µC ATMega and the 868MHz transmitter module.
The changes to the ELV / Conrad RSU are
- remove of the 868MHz transmitter module
- remove the μC ATMega
- tap off the 230V AC button signals from IC101 and IC102 pin 4 (ESP-12 GPIO12 and GPIO13)
- control the relays via ST1 and ST2 (ESP-12 GPIO4 and GPIO5)
The two ELV-RSU boards (upper and lower) should be seperated. Sawing the pin headers is the easiest way. A separation with the side cutter is not recommended since the pins are hollow inside and are deformed using that tool. Therefore also caution when sawing, the pins bend very easily. Afterwards you can put a soldering wire rest in the hollow pin and put them together. This makes it easy to solder the sawn-through pins exactly over each other again.
After separating the two halves of the board we process the cover plate:
- unsolder the 868 Mhz transmitter module
- unsolder the ATMega μC IC100 - the µC disturbs the IO signals and needs unnecessary power. For unsoldering either use a hot-air gun or a lot of tin-solder and put it over all 4 sides of the µC until it will be unsoldered.
- solder two wires on pin 4 at each of the two IC101 and IC102. The wire of IC102 pin 4 comes through the hole of the antenna, the wire of IC101 pin 4 comes through the notch on the edge of the board.
The following picture shows the original solder components and the ESP-12 connection points:
Preparing the ESP-12 module: In order for the ESP-12 module to run we need to bridge two contacts besides 3.3 V and GND
- EN must be connected to Vcc (3.3 V)
- GPIO15 must be at GND (side by side).
Connecting the ESP-12 to the RSU cover board: Simply put the ESP-12 on top of the upper board (use the place of the removed 868 MHz transmitter module).
- One wire connects to 15-GND bridge 16-GPIO15 and this one to the large contact area (GND) of the original 868MHz transmitter module
- One wire comes to VCC bridge EN and this to the contact pad next to dimensions of the original 868MHz transmitter module
- One wire connects GPIO5 to ST1
- One wire connects GPIO4 to ST2
- The wire from the hole (IC102) will be connected to GPIO13
- The wire from the notch (IC101) will be connected to GPIO12