Tag Archives: Remote ESP Programming

ESP8266 Remote Access

Notice I titled that remote access as against remote programming – but that’s part of it.

Years ago, having gotten sick and tired of dismantling my home control Arduinos just to upgrade the code, I purchased a couple of small units from China which I’ve just thrown in the bin.   One had a USB plug on it and plugged into the PC, the other had an FTDI output on it. Both had those black 2.4Ghz antenna.

So the purpose of these units was to wirelessly replace an FTDI – or serial programmer, the idea being that instead of bringing the Arduino project back to wherever one programs the devices, you plugged the unit into the project and over the air programmed it.

At the time I was using Arduinos and those CHEAP £1.50 radio modules – the NRF24L01s, the worst radio boards in the world who’s range could be so bad you’d be lucky to get through one wall. I had high hopes for them with a great mesh network called RADIOHEAD, but ultimately their range and lack of ability to read signal strength doomed them.   However, as you can imagine they were dotted all over the house and I thought this little radio pair would solve the issue of programming them without ripping everything up.

It turns out the “radio FTDI” had the same problem – it was based on the NRF24L01.

Fast forward to September 2015. Here I am in Spain with a new setup of ESP-12 modules controlling lights, watering system and a lot more.  I’ve made some improvements to our “home control 2015” software in the ESPs and once again I find myself having to dismantle kit.

Now, I know that is it possible to program over the air – a few guys have tackled this successfully and indeed much of the code is built into the Espressif SDK. Right now my friend Aidan is working on adding this to our code but there are two issues, he’s not had luck up to now and secondly as our code comes to something like 300k you’re never going to be able to add this to the ESP-01 modules (we use ESP-01 sometimes, ESP-12 other times…)  as you need as much spare storage as you have code for OTA programming!

It was with that in mind that last night I dragged out the old FTDI boards to see if I could save myself the effort of dismantling the Pergola lighting system to update it.  Suffice it to say that I managed to get a few bytes programmed before that all came to an end despite several attempts. With around 25 WIFI units of one description or another dotted around the place, the old wireless FDTI (same frequency range) simply could not handle more than a few feet.


I figured it would not hurt to look around and see if someone has alternative wireless solutions – lots of time has passed since I bought that kit.

And so it was that I stumbled upon this.  https://github.com/jeelabs/esp-link – as it happens it is quite new – essentially what we are looking at is a single unit (yes, that had me going for a while) which will hook into the WIFI system and act like an FTDI – given that you can fire the serial out of your PC over TCP to a port – port 23.   I grabbed the code (the stable 1.04 version) and very excitedly blew it into an ESP-01 unit I had lying around.

Really, nicely done web interface (with remnants of Martin Hanzarov’s code in there) and a really good write-up – indeed there may be enough info in there to help us implement our own FOTO (over the air) updates to our code.

But this has far wider implications – a virtual serial link would also let you monitor the serial line of a remote unit for debugging info – and our units do indeed put out lots of serial debugging info. It would also let you remote program and monitor un-wirelessly enabled Arduino projects.

So the first problem was – I had this unit sitting as on my network and I needed to blast info into port 23 to have it come out as 115K serial.  I have ECLIPSE sitting on the PC running my projects and there’s a line in the MAKE file that says “COM6”.  I have absolutely NO idea how to turn that into a TCP statement if indeed it can be done (FEEL FREE TO START TYPING IF YOU KNOW HOW).

So I turned to a 30 day trial of a PC program that promised to provide a “virtual com port” – and that it did. Serial/IP Redirector let me create a link to port 23 and ship raw data back and forth to COM22 (which doesn’t exist on my PC)- LO AND BEHOLD I set it running, put PUTTY on the PC talking to COM22 and with a real FTDI attached to the little ESP-01 board on real COM6 I set that running on a terminal –at 115K. Utterly flawless raw serial communications – rock solid.

I was getting excited by now. I took my ESP-01 board and cross-connected the serial to an ESP-12 test board. I held GPIO0 to ground and turned the power on, putting the ESP12 into programming mode.

I punched COM22 into the ECLIPSE project and hit the FLASH button on the project. Lights flashed on both units. With a scope attached  to the serial in on the ESP-12 I could see clean 115k data going into my project and… nowt, zilch, nothing.

I was up until the early hours ensuring the baud rate was ok and that my level conversion wasn’t getting in the way – you see all my projects use a resistive divider on the serial input of ESP boards so the whole lot will work just fine with 5v logic on the FTDI and elsewhere.  I wondered if hooking two of these units together with serial cross connected might prove too much but the scope says no – it says I’ve a perfectly reasonable serial signal going into the ESP-12 – but it’s not having it – no responding output whatsoever. Eclipse tries sending out data over and over and eventually gives up just as if there’s nothing connected.

So near and yet so far.

I got up this morning and the unit was still rock-solidly connected to the WIFI and typing a few characters provided perfect results at the other end – but I cannot program ESP units – yet.

Very exciting, yet very frustrating.

Perhaps coffee and a new start to the day will help. BUT I had to bring this to you as the article is really good, the software seems to WORK and there’s a super-bumper version with it’s own OTA updating in the works for larger targets like an ESP-12 (more FLASH) than the ESP-01.

I’m sure this is going to be a winner – just need to get it to work. After all, the ability to add remote programming to any FTDI-enabled project for what, a couple of quid.. well, you just can’t ignore it.

Meanwhile if anyone reading this firstly knows how to set COMX on Eclipse (on Windows) to TCP – do let me know – and if you really think you know what I’m doing wrong here and want to jump in before I figure it out – by all means – you have the keyboard…