ESP8266 WiFi LED dimmer Part 3 of X: Flashing and programming the ESP-01

To get started with the ESP8266 ESP-01 I recommend flashing and programming it before soldering it down. This way you know it’s working and that the program code is also functioning. Depending on how you mount it on your board it can be a bit hard to do so later on!


Connect the board to USB using an Arduino or Serial-to-USB adapter

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On the photo I used an Arduino Nano v3 (Chinese version) as a USB to Serial bridge. If you load something into the Arduino that doesn’t use the serial pins (such as the blinky sketch) this should work without problem.
A little warning, since the Arduino has 5v on it’s serial pins you will need to supply the ESP-01 with 5v also. This is officially NOT supported. For me this has worked without problems for about a week now, but you’re warned. 😉 Mixing 3.3v and 5v also does not work. I recommend using the USB-to-serial adapters I mentioned in the previous article since you can select the output voltage on it and it can also supply a little bit more power then an Arduino can. With the Arduino on USB as a power source the lights would flicker a lot and serial input could be very spotty (often corrupt) with WiFi also connected. With disconnected WiFi it is manageable though certainly not perfect.
With the adapter it’s easy. You just need to connect the right pins together with some dupont cables (See previous post).

Firmware flash mode

To get the ESP-01 in firmware flash mode we will need to connect it in a special way. 
Schematic overview of the ESP-01. Mind the orientation of the board, this is viewed from the top side

Normal running mode

The default pins to connect are:
ESP-01 VCC – 3.3v Serial Adapter
ESP-01 GND – Ground or Minus Serial Adapter
ESP-01 RX – Connect to TX on Serial Adapter
ESP-01 TX – Connect to RX on Serial Adapter
ESP-01 CH_PD – 3.3v Serial Adapter

Since two pins need to be connected to 3.3v it’s easiest to either use a breadboard with some dupont cables or a screw connector block to multiply the connection.
This will set the ESP-01 in normal operating mode. 

Flash mode

To get into firmware flash mode you need to make two additional connections, easiest is to use a screw connector block or breadboard for this.

ESP-01 GPIO0 – Pull low by connecting to ground / minus
ESP-01 GPIO2 – Pull high by connecting to 3.3v
When you reboot the module it should be in firmware flash mode!

Downloading the software

The next step is to get the software. I am using the NodeMCU firmware with the LUA language to make it all work. There are three sources for this, there is and there is the NodeMCU website
The third source is directly from Github, this should always contain the most recent version of the firmware and programs. I recommend using this way and I will describe it here. 
Go to and go to the nodemcu-firmware part. There you click the “Download Zip” button on the right of your screen. 

You should end up with a zip file with all the files in it. Extract it. The files we are looking for are located in the nodemcu-firmware-masterpre_build.9.4512k-flash directory and the file we are going to flash is nodemcu_512k_latest.bin
Then go back to and select nodemcu-flasher and do the same (Download zip). Extract it into a directory and run the program located in the Win64/Release directory.
It should show you window like this:
Begin program
Next go into the second tab “Config” and use the machine cogwheel button and select the nodemcu_512k_latest.bin
If your ESP-01 is connected correctly and in firmware flash mode it should automatically fill in the MAC addresses when you click flash. The following should take place:
When flashing is successful we can continue. 

Sadly, this isn’t as easy as it was written here, it should be, but the 3 modules I flashed needed toying and trying again and again for about an hour each to actually get it to go into flash mode. Once it did there was no problem and it flashed just fine, but still it was a bit hard to get it do so sometimes. I still don’t know yet why it doesn’t always work the first time, it might be because I was using a 5v Arduino.
Once you have managed to get the firmware flashed, disconnect the firmware flashing pins:
ESP-01 GPIO0 – Pull low by connecting to ground
ESP-01 GPIO2 – Pull high by connecting to 3.3v

Installing the QuinLED program on the ESP-01

For sending the programming to the ESP-01 I recommend downloading a tool called ESPlorer, you can download it here. It’s a JAVA based tool so you need to install the latest Java version to run it. Sadly Java also has some downsides, when coding for a while inside of ESPlorer it can slow down quite a lot especially when sending the code over serial to the ESP-01. Restarting the program quickly fixes the problem, but it kind of sucks. Hopefully the author of the program is able to fix this!
Having started the program you will be presented with the main interface:
On the top in the right you can select your COM port (check in device manager) and select 9600 as the baud rate. Hit connect and you are connected to the now LUA running ESP-01 over serial.
Here you can issue commands to the ESP-01.
Some useful commands to remember:
  • node.restart();  –  Restarting the ESP8266
  • wifi.setmode(wifi.STATION)  –  Setting it to WiFi client mode
  • wifi.sta.config(“SSID”,”PASSSSS”)  –  Connecting to your WiFi network
  • print(wifi.sta.getip())  –  Get the IP of the ESP8266
  • wifi.sta.connect()  –  Connect to the set SSID
  • wifi.sta.disconnect()  –  Disconnect wireless
  • print(“Hello World!”)  –  Print some text
You can paste these commands in the little white box next to send and then execute and select them quickly when you need them.
To install the QuinLED dimming program you need to paste the following in the code window:
This is version 0.4 of my code, it will probably get updated at some point. I also need to add some documentation in the code at some point. 😛

pwm.setup(3, 1000, 005)
pwm.setup(4, 1000, 005)






    if string.find(payload,"LED1") then
     LED1_target=tonumber(string.sub(payload, 13) )
     print("Received LED1 Target Value: "..LED1_target)

     if (Stepcounter1) < 0 then
      else PosStepcounter1=(Stepcounter1)
     if (PosStepcounter1) == 0 then
      else PosStepcounter1=(PosStepcounter1)

     if (DimTimer1) == 0 then 
      else DimTimer1=(DimTimer1)

      print (Fadetime1)
      print (Stepcounter1)
      print (PosStepcounter1)
      print (DimTimer1)
      print (LED1_current)
      print (LED1_target)

    tmr.alarm(0, (DimTimer1), 1, function() 
     if LED1_current < LED1_target then 
      LED1_current = (LED1_current + 1) 
      pwm.setduty(3, LED1_current)
    elseif LED1_current > LED1_target then 
      LED1_current = (LED1_current - 1) 
      pwm.setduty(3, LED1_current)
    elseif LED1_current == LED1_target then tmr.stop(0)
     end end )

    if string.find(payload,"LED2") then
        print("Received LED2 Target Value")
     LED2_target=tonumber(string.sub(payload, 13) )
     if (Stepcounter2) < 0 then
      else PosStepcounter2=(Stepcounter2)
     if (PosStepcounter2) == 0 then
      else PosStepcounter2=(PosStepcounter2)

     if (DimTimer2) == 0 then 
      else DimTimer2=(DimTimer2)

      print (Fadetime2)
      print (Stepcounter2)
      print (PosStepcounter2)
      print (DimTimer2)
      print (LED2_current)
      print (LED2_target)

    tmr.alarm(1, (DimTimer2), 1, function() 
     if LED2_current < LED2_target then 
      LED2_current = (LED2_current + 1) 
      pwm.setduty(4, LED2_current)
    elseif LED2_current > LED2_target then 
      LED2_current = (LED2_current - 1) 
      pwm.setduty(4, LED2_current)
    elseif LED2_current == LED2_target then tmr.stop(1)
     end end )

print ("Booted to QuinLED_ESP8266_V0.4")
Be sure to change the SSID and Passcode to what you use in your own network. 

When you have it pasted in ESplorer press the “Save to ESP” button to transfer it over. It will ask you for a filename and where to store it. The where is only a local place what the file will also be kept, the filename is important and I recommend you name it “init.lua”. That way it will automatically run when the ESP-01 boots.

The tool should now be pasting the code to the ESP-01 line per line and checking if it made it across intact. I sometimes have that the code will arrive corrupt and the tool will error. When that happens I recommend you give the ESP-01 a restart and then a WiFi disconnect command. Doing that always makes the ESP-01 much more stable for me and transferring the program shouldn’t be a problem.

Once the ESP-01 is programmed it might complain that it can’t start a second TCP server (it depends on what you where running or if you had some fail flashes). Just give the unit a reset. 

Once it’s booted again you can use the above mentioned commands to ask for it’s IP. You should be able to ping that IP. Don’t be alarmed by it’s ‘not so great’ ping times, this is normal.


Issuing commands to the ESP-01 running QuinLED

Now that our unit is running the QuinLED program you should be able to send commands to it. If you still have a serial connection open it will post some logging about this too.
For sending the commands to the ESP-01 you can either use a putty session in RAW mode to open the TCP port (43333) and type in or paste your command or use a little tool called “netcat”. It is available on most Linux distributions or you can get it in cygwin when running Windows.
To send a command to LED1 you type:

echo LED1_target=1000 | nc ip.ip.ip.ip 43333

That should said GPIO0 to a duty cycle of 1000. A duty cycle can be anything in the range of 0 to 1023. Do not use a number higher then that because right now the program will crash. 😉 It’s no use anyway because the ESP8266 supports 1024 PWM duty cycle levels so 1023 is fully open.

And that should be it, you can now control both channels of the ESP-01 connected to your LED strip. In my next post I will explain how you can hook this up into Domoticz and give it control over both channels independently.

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29 thoughts on “ESP8266 WiFi LED dimmer Part 3 of X: Flashing and programming the ESP-01”

  1. Congratulations with a very well written blog post, explained in good detail!
    There is a small typo just after the Lua code. It should not say "Send to ESP", but "Save to ESP".

  2. Thank You for your great guide !
    I do have a problem though, instead of a led strip i use as a load a led street lamp that has 40 leds of 1W and is driven with a 30Vcc led driver.
    My issue is that the leds never stay full on, they basically blink all the time, which is annoying.
    Regardless of the duty cycle, i can see the code dimms the light but the leds are always blinking, coul dit be that the MOSFET can't sustain the gate open and cycles from closed to open ?
    Any ideas ?

  3. When I have noticed this it was because the power supply was constant current and not constant voltage. Because of that the power supply keeps trying to adjust constantly in the range it can, but because of the PWM it becomes confused.

    Best is to measure the voltage at full power, get a power supply to match that power supply, add in my board and then use PWM. I'm doing that with several LED lamps too and it works perfectly.

  4. This really works well..Thank you. I'm trying to control my ledstrip and add a PIR sensor to this ESP module. Do you have any suggestions on how to get the sensor reading from PIR and send the output to the LED strip. So i guess the ESP will be listening for the LED output settings and should send PIR sensor data back to Domoticz?

  5. Hi I get the following error while trying to send the command : echo LED1_target=1000 | nc ip.ip.ip.ip 43333 to the dimmer :
    stdin:2: '=' expected near 'LED1_target'

    I can't figure out why tis is happening, please help me

  6. Socat does not hang like nc, I recommend sending the brightness like this:
    echo LED1_target=500 | socat – TCP:ip.ip.ip.ip:43333

    Awesome project! I got my first one up and running today, including learing how to flash LUA on the esp8266.

  7. There are 3 adjacent LEDs on my strip that randomly flash at different brightness levels when I set the brightness to 1023. At 1022 and below they act normal.

  8. Hi there! I know this is somewhat off topic but
    I was wondering which blog platform are you using for this site?
    I’m getting fed up of WordPress because I’ve had issues with hackers and I’m
    looking at alternatives for another platform. I would be awesome if you could point me in the direction of
    a good platform.

  9. Hi there.

    I’m playing around with one of your boards, but it would seem that I can’t get full power coming through the MOSFET to the LED lights. I’m measuring 3.44 volts (what the voltage step-down module is set to) between the GPIO and the negative terminal, but I’m only getting ~7.6V on the LED outputs, I can definitely get the LED’s full power direct on the power supply.

    I’m curious if maybe I got the wrong MOSFET’s and they require more voltage to turn on fully. I ordered STP16NF06L from aliexpress, and they are stamped with the “L” on the chips, but they could be miss-labelled (they are super cheap from china after all). Do you think this could be the cause?

    P.S. I distinctly remember NOT using your link because I found a cheaper listing, so I feel that this might be the problem.

    1. Awesome to hear you are using some of my boards! Sadly, you have a common issue with getting the MOSFETs from China. The one’s you receive probably need ~5v to fully open the gate.

      A quick test you could do is raise the DC-DC voltage converter to 5v and see if that makes the MOSFET give more output power. It probably will but that will tell you that the one’s you got, aren’t fully triggering at 3.3v as they should. If that is the case, definitely raise a complaint with the seller and explain the problem. They probably know but try anyway.

      The link I currently provide certainly isn’t the cheapest, but I’ve heard back from others that the MOSFETs they are getting are working correctly! Otherwise, see if you can maybe source them cheaper locally? Aliexpress is great but for these MOSFETs it seems very hit or miss. 🙁

      1. Thanks,

        You’re correct. I tested with 5V across the MOSFET and it works with full power then.

        I’ve managed to find an online retailer here in Canada that sells them, I’ve also found “STP85N3LH5” from the same manufacturer that’s on sake and cheaper. Looking at the data sheet it would seem that it would also work (just with faster switching and higher current ratings, but still with the 2.5V gate threshold). I might give that one a try. I’ll let you know if it works.

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