Node with ESP8266 and RFM95W

niels · February 12, 2016, 8:23am

This can mean two things

you defined your code to use a RFM95W/SX1276 while a RFM92W/SX1272 is connected… to change this, in your .ino change the below line (change into SX1276):
#define CFG_sx1272_radio 1
your wiring is incorrect, or module just not working

rvweert · February 12, 2016, 8:50am

Hi Niels,

I have a RFM95W/SX1276 and it is also defined like this (I assume you mean in config.h):

#define CFG_eu868 1
//#define CFG_us915 1
//#define CFG_sx1272_radio 1
#define CFG_sx1276_radio 1

So seems alright… I’ll double check my wiring then, thanks!

niels · February 12, 2016, 9:30am

that seems to be correct indeed …

davemee · February 12, 2016, 11:52am

Thanks for the confirmation of this, BoRRoZ - we’d be hoping to find a way to patch or intercept the firmware on theRN2483. Seems a lost opportunity for some lightweight, low-cost use cases.

BoRRoZ · February 12, 2016, 12:50pm

I agree… (and I think it will happen in future versions)
but doing it yourself… mmmm

rvweert · February 14, 2016, 12:40pm

Okay, I’ve got it running and first message was sent and received!
Now, the signal is really weak, it doesn’t work anymore if I am more than 300m from the gateway. So I suspect my antenna not to be really working, for now I soldered a 10cm wire to the ANT pin of the RFM95W. Does anyone have suggestions on how to improve this considering the device needs to be as small as possible?

Thanks!

René

jpmeijers · February 14, 2016, 2:14pm

Firstly try to make your antenna 8.6cm long. This is a quarter wavelength at 868MHz. Anything longer or shorter will perform worse.

What you can do to make the antenna more compact is to coil the antenna (helical antenna), by winding it around something like a pencil. This will however perform a little less good, but is a good compromise. Similar antennas are commonly used and available for 433MHz here.

rvweert · February 14, 2016, 3:26pm

Thanks jpmeijers, it works! Don’t have to drive to a gateway anymore now (still waiting on a part for my own)…

arthoo · February 14, 2016, 3:49pm

https://github.com/OpenHR20/OpenHR20/wiki/2.1)–433-MHz-and-868-MHz–Antenna-Design-Examples
use the complete above line as url. The board software seems to screw it up.

This page contains the working link:
http://openlora.com/forum/viewtopic.php?t=867

or google: 868MHz antenna helical

sergiosena · February 19, 2016, 9:57am

@davemee

The reserved pins on the module are clearly the programming pins for the ICD.

The LoRa and LoRaWAN code can be ported from IBM-LMIC or Semtech and flashed onto the PIC with minimal changes only related to the HAL.

For large quantities if one wants to run own code inside the PIC, then it is a viable option.

You would of course loose certification but maybe you are not concerned about that.

JDP · March 10, 2016, 1:13am

Davemee - Why not ask your friendly Microchip salesman to bundle an 8-pin PIC12 to run the application and drive the RN2483 UART. It costs next to nothing, and isn’t much bigger than a regulator or bulk capacitor.

arjanvanb · March 19, 2016, 4:04pm

Just in case it helps anyone getting here given this topic’s title: Arduino LoRaWAN sketches for the Ideetron Nexus board.

The Nexus board is not an ESP8266, but an Atmel ATMEGA328P with RFM95W or RFM98W. I’ve not used it, nor the above sketches.

@rvweert, what’s your final setup with the ESP8266 and RFM95W?

greger-isaksson · March 20, 2016, 8:55am

I recognized that the TTN gateway will not be available soon and that Microchip RN2483 is out of stock. Just too have something working in short time I found out that a very cheap and simple experimental setup with an single_channel_gateway, https://github.com/tftelkamp/single_chan_pkt_fwd
built on RPI and SX1272, and a node built on ESP-12 (ESP8266) and SX1272 is possible.

matthijs presented an updated version of arduino-lmic library 29 days ago. https://github.com/matthijskooijman/arduino-lmic.
The code will compile for ESP8266 in Arduino IDE without problem and with some small modification as below it is possible to force transmission to only one channel, the same channel as the single-channel-gateway is listening on. The pin mapping can also leave dio3 unused as I will not use the FSK channel at all, this means that I can use the serial port for input of new data for transmission.

// Pin mapping
const lmic_pinmap lmic_pins = {
.nss = 15,
.rxtx = LMIC_UNUSED_PIN,
.rst = 16,
.dio = {5, 4, LMIC_UNUSED_PIN},

SX1272 dio2 → GND // Only used for PSK, not used in my case

//Changes in Arduino code, setup

// configures the minimal channel set.
LMIC_setupChannel(0, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(1, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(2, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(3, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(4, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(5, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(6, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(7, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band
LMIC_setupChannel(8, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),  BAND_CENTI);      // g-band

// LMIC_setupChannel(1, 868300000, DR_RANGE_MAP(DR_SF12, DR_SF7B), BAND_CENTI); // g-band
// LMIC_setupChannel(2, 868500000, DR_RANGE_MAP(DR_SF12, DR_SF7), BAND_CENTI); // g-band
// LMIC_setupChannel(3, 867100000, DR_RANGE_MAP(DR_SF12, DR_SF7), BAND_CENTI); // g-band
// LMIC_setupChannel(4, 867300000, DR_RANGE_MAP(DR_SF12, DR_SF7), BAND_CENTI); // g-band
// LMIC_setupChannel(5, 867500000, DR_RANGE_MAP(DR_SF12, DR_SF7), BAND_CENTI); // g-band
// LMIC_setupChannel(6, 867700000, DR_RANGE_MAP(DR_SF12, DR_SF7), BAND_CENTI); // g-band
// LMIC_setupChannel(7, 867900000, DR_RANGE_MAP(DR_SF12, DR_SF7), BAND_CENTI); // g-band
// LMIC_setupChannel(8, 868800000, DR_RANGE_MAP(DR_FSK, DR_FSK), BAND_MILLI); // g2-band
// TTN defines an additional channel at 869.525Mhz using SF9 for class B

jpmeijers · April 1, 2016, 12:05pm

I was struggling very much to get an ESP-12-E and a RFM95 to work together and run LMIC, and transmit a packet to TTN. The biggest issue I had was figuring out which pins on the ESP should be grounded, and which should be pulled high. And when and in which order. I finally got the whole thing working yesterday.

In this post I’ll give an outline of how I connected everything. Next time I will hopefully summarize what I had to do to get the software side working, as different library versions caused some headaches.

The ESP8266 module I have is this one: http://www.esp8266.com/wiki/doku.php?id=esp8266-module-family#esp-12-e_q

My final connection diagram looks like this:

Things to take note of:

The ESP should be powered from an external 3.3 volt source, not via USB. Big capacitors are needed to suppress the spikes of current the ESP module needs during startup. USB does not like big caps on its voltage lines.
The ground connection of the ESP should be connected to your power supply and the USB-UART (FTDI) board.
Note the pull-up and pull-down resistors on pins GPIO0, GPIO2, GPIO15, EN and Reset of the ESP module. This is very important for the ESP to boot up into the correct mode, as well as the SPI slave select line to work.
To boot the module up in programming mode, hold down switch “Program”, then press and release switch “Reset”, and then release switch “Program”. After a successful program, press and release the Reset switch to boot up into normal mode.

jpmeijers · April 7, 2016, 7:42am

As I mentioned in my previous post, I also had a number of software issues to sort out before my ESP+RFM95 node worked. Here is a step-by-step guide of the steps I was able to reproduce to get a working node.

Go to https://github.com/things4u/LoRa-Thing and download zip file.
Unzip.
Copy “esp-lmic-v1.5” to your Arduino sketch folder.
Copy “libraries/base64” to the libraries folder in your Arduino sketch folder.

Go to https://github.com/tftelkamp/arduino-lmic-v1.5 and download zip file.
Unzip.
Copy folder to the libraries folder in your Arduino sketch folder.
Inside this folder go to src/lmic/config.h and comment out line 10 (//#define CFG_sx1272_radio 1) and uncomment line 11 (#define CFG_sx1276_radio 1).

Open Arduino IDE 1.6.7
Go to Tools, Board, Boards Manager. Install “esp8266 by ESP8266 Community”.
(Arduino IDE may need a restart)
Go to Tools, Board and choose Generic ESP8266 module

Open esp-lmic-v1.5.ino from the folder which you copied to your Arduino sketch folder in the first step.
Comment out line 32: //#include <ESP.h>
Line 33 should not start with a capital letter: #include <base64.h>
Change line 59 to your device address.

The sketch should now compile without errors.

Follow the procedure in my previous post to program and reset the ESP8266 module.

If you open the Arduino serial monitor at 115200, you should see the following messages (or similar) after a couple of seconds:

Starting
os_init() finished
LMIC_reet() finished
LMIC_setSession() finished
LMICsetAddrMode() finished
Init done
Time: 21
Send, txCnhl: 0
Opmode check: ok
Event EV_TXCOMPLETE, time: 34

After about two minutes you should see the following text (or similar) appear:

Time: 141
Send, txCnhl: 7
Opmode check: ok
Event EV_TXCOMPLETE, time: 154

Every two minutes a packet is sent to TTN. You can check on the TTN API if this is the case.

Some observations and guesses why the code does not work out of the box:

It seems like there are multiple Arduino libraries for the ESP family of modules. I chose the one that is listed in the boards manager, as it is the easiest to find/install/update and thus the most likely one for a beginner to use. The original author of the esp-lmic example sketch likely used a different version, and therefore had to include ESP.h.
There are numerous LMIC libraries around. I tested quite a few, but the only one I could get to compile was the one linked to in step 2. Some of the newer versions of the library does not handle the ESP correctly in their precompiler directives. Some are also using a different ESP-Arduino library.

cswiger · April 14, 2016, 12:46am

Just got the things4u esp8266 sketch working with the Modtronix inair9b here in US915 land, with an esp8266-03 (NOT recommended, just what I had laying around while the Wemos D1 mini is on order) - which took a bit of a hardware trick to use GPIO0&2 for DIO0&1 - namely, power on with GPIO0&2 disconnected, then plug it into DIO0&1, believe it or not that works!

Next, it looks like the LMiC library starts from a random channel 0 thru 63 (902.3 + chnl*0.2 MHz) and walks up to 63 then starts over from 0. Just stuck a horrible hack in lmic.cpp to fix it on channel 57 (913.7) - well, after the first transmission on channel 0, then update my single channel gateway and the temperature node.

Now TTN REST reports:
“data_plain”: “Hello ESP8266 world!”

Learning LoRaWAN and LMiC is going to take me a while

arjanvanb · April 14, 2016, 4:42am

You could also add a loop in your own sketch, calling LMIC_disableChannel(i).

(And remember, for a real node, don’t send text.)

jpmeijers · April 15, 2016, 7:13pm

In my previous post about the software setup to program an ESP8266, I missed one step.

After installing the Arduino IDE, you have to go to File->Preferences, and next to Additional Boards Manager URLs, add the following URL: http://arduino.esp8266.com/staging/package_esp8266com_index.json

Now in Tools -> Board: -> Boards Manager, search for ESP, and choose to install esp8266 by ESP8266 Community version 2.2.0-rc1

Another issue I encountered was that my ESP module constantly crashed with an exception:

Exception (3):
epc1=0x401003e9 epc2=0x00000000 epc3=0x00000000 excvaddr=0x400248c9 depc=0x00000000

Which translated to:

calloc at /opt/arduino-1.6.7/hardware/esp8266com/esp8266/cores/esp8266/umm_malloc/umm_malloc.c line 1682

After a very long search I found a sollution that worked: http://wifiesp.com/?p=14

Basically I had to add this block of code at the start of my setup function:

uint16_t s,res;

os_printf("Erasing sectors\n");
for (s=0x70;s<=0x7F; s++)
{
  res = spi_flash_erase_sector(s);
  os_printf("Sector erased 0x%02X. Res %d\n",s,res);
}

Adri20 · April 19, 2016, 11:45am

I just found these 2 items. They look like a match made in heaven (for this particular topic).
Does anyone have experience with this combination?

It is a ESP8266 in an Arduino formfactor with an Arduino-Lora-module.

A combination of:

(the version on Ali is already a newer version mine is 1.1)

Anyone?

Batilan · April 19, 2016, 4:56pm

I was lucky enough to receive the first revision of the Dragino LoRa board: it simply works.

As it is basically an RFM95 breakout it should work together with the ESP, you might want to consider the V1.2 board as that is more flexible w.r.t. the breakouts. It was revised based on inputs from people on this forum to make it more flexible see the dragino wiki for the difference in appearance.

For ESP8266 LMIC stack see messages above.