Sonoff 4CH and 4CH Pro

Niccolò Maggioni edited this page Mar 7, 2018 · 12 revisions

Sonoff 4CH

Other than most Sonoff modules (ESP8266) the Sonoff 4CH is based on the ESP8285.

Sonoff 4CH Pro

Compared to the 4CH the main differences/improvements of the 4CH Pro are:

  • Relays are isolated from mains and can each switch their own circuit (mains or low voltage).
  • With stock firmware special modes are supported (stand-alone schedules, inching, interlocking).
  • RF receiver (optional key fob or Sonoff RF Bridge 433 required).
  • Dual microcontroller, both a ESP8285 and a STM32.

Serial Connection

Sonoff 4CH

Please see the Hardware Preparation page for general instructions.

As always, you need to access the serial interface. The four serial pins (3V3, Rx, Tx, GND) can be seen in the first picture. Attention: The printed labels on the PCB for Rx and Tx are incorrectly swapped as can be seen on the image.

The Sonoff 4CH features four hardware buttons of which one is already connected to GPIO0, which hence can be used to bring the module into Programming Mode. The button is shown on the second picture.

Sonoff 4CH Pro

The "FW/IO0" button (Switch 1) is not directly connected to GPIO0 of the ESP module. A different method has to be used to program this board.

To program the ESP chip disconnect power from the board, connect a cable from any Ground (GND) pin to the GPIO0 pin on the ESP (be careful not to touch any of the other pins). This is the second pin to the right on the top row of pins (see picture). While holding the pin connected power on the board. The board does not respond to any button pressed when in programming mode and LED 1, 2 and 3 are on (might differ per board).

Use the ESP programming header as described in the picture to upload the firmware and follow regular programming procedure.

Sonoff 4CH Pro R2

On the R2 module the GPIO0 pin is broken out to a small pad to the right of the ESP package:

Solving Sonoff 4CHpro programing issues

If you have problems to program the 4CH-pro, you might find below tips useful:

  • Basic) Use the ESP program header and ensure that the right port is set in the Arduino IDE.
  • Basic) TX/RX are printed correctly on the pro version => TX goes to RX PIN and RX to TX.
  • Basic) GP0 needs to be connected to ground 3 seconds after reboot !!! If not you can not program it.
  • Step1) If you use windows7+, check in the device manager if the port is not added/removed all 2 seconds. => If yes then your USB port does not deliver enough ampere.
  • Step1) Or/and reduce upload speed to 57600 in Arduino IDE.
  • Step2) Use an active USB HUB if your computer delivers not enough ampere => External power source will stabilize the 4CH-pro and you can increase upload speed back to 115200. => Using a Laptop instead of a Desktop Tower might also do the trick as Laptops have a battery to deliver more ampere.

Solving OTA and Upload Problems

Where most Sonoff's are ESP8266 based the Sonoff Touch and Sonoff 4CH are based on the ESP8285.

It is important to initially flash these devices with the correct FlashChipMode of DOUT as otherwise future OTA or Upload updates will fail.

In the Arduino IDE select Board Generic ESP8285 Module as this contains the default DOUT option. You could still use the Generic ESP8266 module as long as you set parameter Flash Mode to DOUT.

Starting with version 3.9.12 after first restart make sure to select either module Sonoff Touch or Sonoff 4CH at least before any OTA or Upload action.

The OTA or Upload code will now check if one of the above modules is selected and patch the uploaded default ESP8266 code with FlashChipMode DIO to the ESP8285 FlashChipMode DOUT before it is copied to it's final destination.

Starting with version 5.3.0 all OTA or Upload code will be patched for FlashChipMode DOUT whatever Module is selected.

4CH Pro DIPSwitch Configuration

Most special modes of the 4CH Pro are controlled by DIP switch panels on the board. Please refer to the back of the board or the Sonoff documentation for more details. For normal operation with Tasmota the following settings are recommended:

  • S6: 1
  • K5: all 1
  • K6: all 0

(0 and 1 are printed onto the board next to the switch names)

Changing these switches for operations like inching and interlocking are also supported with Tasmota.

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