ESP8266-01S Not responding to AT commands

Hi guys

this is my first topic, greetings to all…
Down to business, I have connected my ESP8266-01S and managed to load and configure it with the examples using my Arduino UNO, but I don’t get to access it bt AT commands, all I get in response is this… (By putting ESP RST-GND) at BR74800. I´ve tried with and without external supply and same problem (external PSupply ATX600w, computer power supply 3.3v)

my ESP8266-01S is working fine, because I can Load all examples to it like WiFi Scan using my Arduino, without the Chip.

Is there a way or workaround for this?
Do I really need to be concerned about this issue before using Blynk or should I just load a blank sketch to my ESP8266-01S and load the Blynk Code in my ArduinoUNO??

Also, I haven’t flashed it, because it works fine when uploading the examples in Arduino IDE for ESP8266


So what did you flash from the Arduino? If you loaded any sketch you will have over wrote the “factory” AT commands.

So if you want to use the UNO you can reflash the AT firmware and figuratively hook the sports car to the ox.

Or to use the sports car by itself put power to chip enable and you can use 2-3 of the gpios on the 8266-01. So if you use iic bus you can do a lot of things with just the 8266

Hi Daveblynk

Thanks for the the reply,
Yes, as you say, Im hooking the sports car to the ox for testing… I need a lot of readings and sensors… so I´m moving to a Mega or DUE soon…

In regards to reflashing AT commands, so I can be able to hookup to Blynk, is that really necessary? or I can leave it as is…

if reflash required? any ideas or best way to do this?
I have tried a lot of methods and haven’t been able to make them work

As you say, if I deleted the AT Commands when I uploaded the Example scketchs, is there an Arduino Sketch that I can Upload to it in the same way as te examples and be done with it???

BTW I´m using an ESP8266-01S… don’t really know if that’s useful information…


When ever we upload a sketch, the firmware will be replaced with our sketch. This this link to flash the firmware. We cannot upload the the firmware like we do with the sketches.

Yes, if you want the ESP to act as a WiFi modem for your Arduino then it mist be configured to listen for AT commands from the Arduino and respond appropriately. The firmware that allows it to do this has been overwritten by your sketch, so needs to be reinstated.

Do all of these sensors need to be in one physical location, asn is one sensor required for each measurement?
In practice, I find that most real world projects tend to monitor one or two things in a single location - water level and temperature of a tank in location 1 for example, air temperature and humidity in an outdoor location, plus the same things in different indoor locations, charging current and battery voltage of a solar system in a different location etc.

In this scenario, things like air temperature, humidity (and atmospheric pressure) can be measured with a single sensor. If the things being measured (and presumably controlled too) are physically dispersed then you either have to run wires from each location to a single controller, or have multiple controllers in different locations.

In my living room I currently have around 10 different ESP8266/NodeMCU based devices. Most are built in to switches to control devices that are plugged in to them, but others take temperature and humidity readings, transmit/receive infrared and 433MHz commands to operated other devices or dona single dedicated job in a particular location.

If you do need everything in one physical location then an ESP32 or a NodeMCU with a port expander is probably a much better and more stable solution.
I’d suggest that you have a read of this before you go much further…


Thanks @PeteKnight

Yes, I require around 30 sensors and actuator to be in a single location, with a specific logic of operation, and react and adjust to constant variable changes, the main goal (after solving this issue, and learning a bit more) is to have a kind of Tree or Hive where they all report to a sub-master and so on… and in the future with each other. (Thats the plan or the dream…)

In regards to flashing the firmware I havent been able to do so using this tutorial mentioned by @Madhukesh (Thanks btw), I tried with version 1.7.3 and 1.7.2, it connects and everything and deletes my code and I end up with…

What type of sensors and actuator(s)?
If you’re going for devices that use I2C then in theory you can have up to 127 connected to a single 2 wire bus, but in practice if they are the same type of sensor and you only get two or three address options per sensor then you’ll run into difficulty very quickly.
In a similar way, if the are analogue sensors then you could, in theory, connect up to 16 to a single Mega, but unless the sensors have very similar cable runs then voltage drop and noise could give you some odd results.

Although the Mega has more memory than the Uno, it still has a relatively small amount and it also has slow processing speed. Without native Wi-Fi connectivity you’ll be reliant on the clunky and somewhat crippled connectivity you get from connecting it to an ESP-01 and will be lacking functionality like OTA and provisioning (but which may not be an issue for you).


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Thanks @PeteKnight, I think I´ll figure that one out when I get there… for this prototipe I would like the ESP to work and start some local testings with Blynk but I cant fireout whats wrong… any ideas?


At last, I got it to flash and respond AT Commands by using this Firmware}

And to upload it I used a simple file loader, that I found in this tutorial


  • when flashing make sure to close all other serial monitors, like Arduino IDE
  • if it does no connect, check connections or reconnect the USB serial port
  • In my case, I used the Arduino Uno as a bridge by putting a jumper between RST&GND of the Arduino.

Thanks for all the help!!.. Now let’s see how it goes hooking it up to Blynk… LoL!!

BTW @PeteKnight, I´ll look into your suggestions once I get Blynk up and running with my current hardware, so I can test it and play around a bit… For the multi-sensor and actuators, my first thought would be to have 2 Megas being controlled by my RasPi, that way I get the best out of 2 worlds, but of course, I’m opened to suggestions.

Have a Great one Guys!!

Cheers!! and thanks again for your time…

It’s difficult to suggest solutions without knowing more about the ‘use case’ for this project and the type of sensors/actuators you’ll be using.

After more than 3 years of using Blynk with various devices, as well as a year or so using Arduinos in other ways, I find it difficult to recommend the Arduino/ESP-01 combo.

The NodeMCU or ESP32 are the hardware I’d recommend, as you already know.
Personally, I use Blynk in a different way to most people. I have remote devices talking to a Raspberry Pi via MQTT messaging, then the Pi talks to the Blynk server via a system called Node-Red. This works well for dispersed nodes around the house that need to interact with each other.
From what you’ve said so far, I’d imagine that this probably isn’t the best option for you, in the same way that to Mega’s probably aren’t the best solution.

I understand you desire to do some proof of concept work with the hardware that you have, but the further you go down that route with the Arduino/ESP the more you’ll find yourself working around the issues thrown up by that hardware.


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@PeteKnight, your prophecy came true…

Halfway through my CODE y ran out of memory… So moving on to MEGA now, with or without an integrated WiFi… (Chinese Version) I believe my code will be around 100Kb, so I think it will get the job done. Not really looking into RsPi for the moment, but I will in the near future, I have to learn a new programing language for that… But the idea would be to have something like yours, a RsPi controlling the Mega or Mega´s…

I want to test all the Arduino options first because of the robust technology and components to treat sensors and actuators, without so many external components.


Personally I wouldn’t describe it as robust technology, just old technology. The Mega has been around for more than 11 years and is outdated in terms of IoT devices.

I use Node-Red, which is a visual programming platform so you can achieve quite a lot with no programming skills at all. Custom Node-Red functions are easy to write and the language is very similar to C++
This topic explains more…


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