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This repo contains documentation and code to interface with pellet stoves based on Micronova controllers

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Micronova Controller

This repo contains documentation and code to interface with a pellet stove based on Micronova controllers. I only tested it with my own stove (L'Asolana Marina), but it should work with all Micronova based stoves. Please note that the RAM and EEPROM mappings will probably be different for other models.

The code is designed to run on a ESP32 and provides a simple TCP socket based protocol to communicate with the stove. There is a python module in ./python to interface with the TCP server in a easy way. The ESP also has a simple, interactive serial shell to communicate with the stove.

If enabled in the build options, the ESP will also provide a HTTP-API with a simple web-interface.

This is work in progress. MR's for more features (for example: MQTT, more locations) are welcome!

Stove

Protocol

The stove has a half duplex serial port, meaning you can either send or recive. It only responds to commands and never sends something by its own. It seems that the protocol is called Rwms. The serial connection needs the following settings: 1200 baud, 8 data bits, 2 stop bits, no parity, no flow control.

There are two accessible memories, RAM and EEPROM. RAM is volatile (but backed up by a battery) and can be rewrote many times safely. EEPROM is the memory used for storing permanent settings and should not be rewrote many times as writing cycles are limited (commonly 10-100k depending on the memory technology).

Reading:

Reading is sending two bytes in the following format:

[LOCATION] [ADDRESS]

Where LOCATION is one of:

  • 0x00 RAM
  • 0x20 EEPROM

The stove answers with 2 bytes, with the following

[PARAM+CHECKSUM] [DATA]

It can be decoded with the following pseudo-code:

data = stove_rx_data[1];
checksum = stove_rx_data[0];
location = checksum - data;

Writing

Writing is sending two bytes in the following format:

[LOCATION] [ADDRESS] [DATA] [CHECKSUM]

Where LOCATION is one of:

  • 0x80 RAM
  • 0xA0 EEPROM

The checksum can be calculated as follows:

checksum = LOCATION + ADDRESS + DATA

if ( checksum >= 256 ){
  checksum = checksum - 256;
}

The stove answers with 2 bytes:

[CHEKSUM] [DATA]

Known locations

Those are only tested for my stove (L'Asolana Marina), it seems like there are different values on different stoves. My Stove has a L023_7 control board.

Type Address Description
RAM 0x00 internal timer of the program (ranging from 0-255 continuously)
RAM 0x01 ambient temperature multiplied by 2
RAM 0x21 power state (0-stove off, 1-stove start)
RAM 0x19 power setting (0-4, only read works)
RAM 0x0a hot air outgoing fan power, seems to be between 0-~50
RAM 0x3E Fumes temperature
RAM 0x02 temp, could be air outlet
RAM 0x37 fumes fan speed
RAM 0x0D pellet loading formula in use
RAM 0x7B Secounds, decimal, read only
RAM 0x7B Day of week, decimal, read only
RAM 0x7C Hour, decimal, read only
RAM 0x7D Minute, decimal, read only
RAM 0x7E Day of Month, decimal, read only
RAM 0x7F Month, decimal, read only
RAM 0x80 Year since 2000, decimal, read only
RAM 0x58 Infrared command, 0x54 P+, 0x50 P-, 0x52 T+, 0x58 T-, 0x5a PWR
EEPROM 0x7d set temperature as 1:1 value
EEPROM 0x7f power, 1-4
EEPROM 0x25 night mode, 0=off, 1=on
EEPROM 0xf8 Day of week (1=monday, 7=sunday)
EEPROM 0xF9 Hour (0x20 = 20:)
EEPROM 0xFA Minute (0x30 :30)
EEPROM 0xFB Day (0x03 3.xx.xx)
EEPROM 0xFC Month (0x12 = x.12.xx)
EEPROM 0xFD Year (0x22 = 2022)
EEPROM 0x50 daily timer enable 0x00=off, 0x01=on
EEPROM 0x51 daily timer 01, turn on time (x10 minutes since midnight)
EEPROM 0x52 daily timer 01, turn off time (x10 minutes since midnight)
EEPROM 0x53 daily timer 01, power, 1-4
EEPROM 0x54 daily timer 01, set temperature
EEPROM 0x56 daily timer 02, turn on time (x10 minutes since midnight)
EEPROM 0x57 daily timer 02, turn off time (x10 minutes since midnight)
EEPROM 0x58 daily timer 02, power, 1-4
EEPROM 0x59 daily timer 02, set temperature

State (0x21) has the following values for my stove:

State Description
0x00 Turned off, send to force off
0x01 Starting/checking, send to turn on
0x02 Turning on phase 1, dont send this
0x03 Turning on phase 2, dont send this
0x04 Stove running, dont send this
0x05 ?, dont send this
0x06 Stopping, send to turn off
0x07 Cooling down running, not sure if sending is safe

Turning the stove on works fine over writing 0x01 to RAM 0x21, turning it off (sending 0x06 to RAM 0x21) seems to be problematic. My stove enters "turning off mode" but takes pretty long to do so (~50min), so this is not the procedure used by programs or the power button which takes around 10min. Searching around in the internet told me that i am not the only one which has this issue. The stove also has a infrared control, which seem to write commands to RAM 0x58. So sending 10 times 0x5a to RAM 0x58 with a delay of 100ms turns the stove off safley.

Sending various IR commands can be done by writing to RAM 0x58 with a delay of 100ms. To set power and temp, send it at least twice, for the power button (longpress) at least 10 times.

State Description
0x54 Power +
0x50 Power -,
0x52 Temperature +
0x58 Temperature -
0x5a Power ON/OFF

Room temperature can be read in 0x01, then divide the value by 2. The display of the stove cannot display decimal places but it seems that the sensor has an accuracy of 0.5°C.

The power (P1-P4) can be changed when writing to EEPROM 0x7f value 0x01 (P1) to 0x04 (P4), then the stove immediatley changes. Manually changing over the display seems to change it also in RAM 0x19, so i would recommend to write it there as well. Another possibility is to set the power over IR commands (see above) which possibly is safer.

The fan speed can be calculated as follows: Take the maximum value of the spins and divide it by 255, the result is offset.

Rpm=(value*10)+offset

The clock in RAM can only be read. To set it, it has to be written to the EEPROM addresses above. The coding seems to be BCD, or base 16 ints, meaning hex 0x16 is value 16, 0x53 means 53 and so on. In Python, a number can be converted as follows:

number_to_convert=20
int(str(number_to_convert),16)

Please see doc/stove-locations.md for more possible locations.

Using the Arduino library

There is a Arduino library in src/micronova_stove.hpp which makes interfacing with the stove more easy, it takes care of checksums and serial settings.

It can be used like this:

#include "micronova_stove.h"

// create the stove object
MicronovaStove stove( stove_pin_rx, stove_pin_tx, stove_pin_rx_enable );

void setup(){
  // init the stove
  stove.init();
}


void loop(){

  // read RAM 0x21 and print result
  stove.read_ram(0x21);
  Serial.println(stove.last_read_value)

  // read EEPROM 0x25 and print result
  stove.read_eeprom(0x25);
  Serial.println(stove.last_read_value)

  // write 0x01 to location 0x21 in RAM
  stove.write_ram(0x21,0x01);

  // write 0x01 to location 0x25 in EEPROM
  stove.write_eeprom(0x21,0x01);

  // turn the stove on
  stove.on();

  // turn it off
  stove.off();

}

Software

Web

pinout

Default port is 80. Can be changed.

ESP Configuration

# open up a serial console to the device, this will give you a interactive shell
make monitor

# read stove state to see if everything works 
read-ram 0x21

# configure wifi ssid & pass
wificonfig ssid-name ssid-password

# configure static IP (ip, gateway, netmask, dns-server)
ifconfig static 10.10.3.60 10.10.1.1 255.255.0.0 10.10.1.1

# configure dhcp
ifconfig dhcp

# set port for the tcp server 
set-tcp-port 9040

# restart to take effect of the settings
restart

# check internet connection
ifconfig

Python module

from python.micronova_client import MicronovaClient

stove = MicronovaClient("10.10.3.60",9040)
stove.connect()

print(stove.stove.get_ambient_temp())
print(stove.stove.get_stove_state())

res = stove.read_ram(0x21)
print(res)

stove.on()
stove.off()

stove.close()

Interface Circuit

The circuit uses optocouplers to do the level-shifting (stove is 5V logic and ESP32 3.3V). The opocouplers also implementing a echo cancellation. For reading values from the stove, one has to pull the ENABLE_RX optocoupler to low, but then no data at TX will be sent to the stove anymore.

The circuit is based on the one from philibertc/micronova_controller

BOM

  • 2x Resistor 150R
  • 1x Resistor 330R
  • 3x Optocoupler PC817 or EL817
  • 1x Step Down Module (20V input, 5v output)

Circuit

circuit

Connector on stove

connector

Pinout Board

(This is my personal board, you have to build one on your own)

pinout

Links that helped me

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This repo contains documentation and code to interface with pellet stoves based on Micronova controllers

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