Hacking a Delonghi DH300 P Humidifier  for IOT automation with ESP8266 and Blynk - Page 1
Forum section: electronics / projects

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 15, 2018, 02:40:42 pm
content: Dear All,I have a dehumidifier (Delonghi DH300 P)http://www.clubic.com/shopping-409870-3-delonghi-dh-300-p.html#443724that I want to automate and remote control. In particular, shut down at night because of the noise, andat peek hours when electricity is much more expensive.I first try with a remote controlled main plug, but it does not work because when turned on, the control board is off,and the device does not start until you press the on button.Same for the pump that is mandatory.I thus decided to hack directly the board, and add an ESP8266 (or similar to it) for wifi control.I have already dismounted the board, but before going further, I am searching here for advice.I need essentially two things :A) Act on the push buttons. The buttons are standard push buttonhttps://www.ebay.com/itm/100PCS-6x6x6-mm-Miniature-Micro-Momentary-Tactile-Tact-Touch-Push-Button-Switch/201538499841?epid=633717124&hash=item2eeca17501:g:hxUAAOSwEOpaA67FI need, for two of them ( ON/OFF and pump) to simulate the switch from the ESP8266.The option I think of is to use a digital switch as the DG412 from intersilhttps://www.intersil.com/content/dam/Intersil/documents/dg41/dg411-12-13.pdfwhich I willput in parallel to the actual button switch.B) Read the led status. For this, I do not see a very obvious solution.The anode of the leds is always 5V.When its on, the cathode turn to 3V, and is 5V otherwise.The ESP8266 I use operates at 3.3V, so I need 3 V logic. I am thinking of using a LM339 quad comparatoras in the attached schematics and hook the output of the comparator directly to the IC IO pin.The reference voltage (4V) is provided by a resistor divider (40k,10k).What do you think ?Will this work ?Is it overkill ?ThanksPS : I will post here the evolution of this project as it can be used for the automation of many devices. The IOT interface will be made using Blynk (https://www.blynk.cc/).

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 15, 2018, 06:24:24 pm
content: Can you get it to turn on reliably every time power is applied by putting a capacitor across the power button?

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 15, 2018, 08:31:59 pm
content: I doubt it .When you power on the DH300, you power the main board with 5V, which has a MCU.( Samsung 3F9488XZZ). If you press the POWER button, the MCU then activate the relaysthat really powers the device.

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 15, 2018, 09:30:28 pm
content: I have actually used the capacitor trick a number of times. It will probably take some trial and error to find a value that works.If you hold down the button and plug it in, does it turn on? If it does, some value of capacitor is almost certain to work.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 16, 2018, 07:24:57 am
content: I dont understand the use of the cap. Could you explain how it will work.In any case, it will not solve my problem, as I want also to have the status of the 4 leds remotely.In addition, I will still need to have the remote wifi plug ( which I did with a ESP8266).If I integrate the ESP8266 to the DH300,I can use the remote plug for other purpose.Can you comment on the solution I propose ?

author: TopGunPk
author_rank: Contributor
timestamp: April 16, 2018, 10:15:22 am
content: You can send it a command to POWER-ON and OFF via IR signals, just like it's remote controller.You can capture the Delonghi IR signal on a software like AnalysIR. It uses simple 4-bits to represent different commands,. You can decode the Power ON /OFF commands.This signal you can generate from an ESP8266.Hope this helps.Regards,Shan

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 17, 2018, 08:04:28 am
content: There is not IR receiver on the DH300P.Here is the schematics of the board I intend to include in my DH300. The JP1 connector will interface with the control board of the DH300 with the following setup :1 : 5V ( I identified it from the board. Most probably the power supply is a Lm7805, so there should be enough power to power this additional board).2: GND3 : power button ( The power is active LOW)4 : pump button (active LOW)5, 6, 7, 8 : control LEDS ( control the voltage of the cathode : 5 V OFF, 3V ON)

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 17, 2018, 10:57:11 am
content: After mounting the board,It was not working.First lesson : I was too optimistic. I soldered directly the nodemcu on the board. I should have put a socket. I had to desolder everythingand put a socket. I had put sockets on the other chips.Second lesson : I am not familiar enough with the nodemcu and ESP8266. I should know that the D8 pin (GPIO15) is reserved as it needs to be pulled down at boot.I have revised the schematics :Moreover I may not need the pullup resistors, and rely on the internal pullup, but will leave it as it is for the moment.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 17, 2018, 11:14:27 am
content: Here is the mounted board on a breadboard like PCB.Not fully tested yet.I still need to make the software.

author: JacquesBBB
author_rank: Frequent Contributor
timestamp: April 18, 2018, 08:10:58 am
content: I have now hooked the ESP board to the two buttons and 4 leds of the main DH300 board.The ESP board find it place very nicely in a free spot of the top of the DH300.Everything is fully functional, and I can now control the DH300 from my phone.I will post the program later on here.I will before add a BME280 sensor to get some improved humidity and temperature measure.