| Pin | |
|---|---|
| 2 | SCL |
| 3 | GND |
| 4 | GND |
| 5 | +15V |
| 7 | SDA |
The SCL, SDA are I2C lines with a 5V pull-up (5,6K) connecting straight to the CPU on the Itho mainboard.
+15V can be used for power supply needs (appears to be good for at least 1A).
There is no +5V available, but is not needed due to the built-in pull-ups (the lines only need to be pulled down for a logical 0).
| GPIO | Desc | Notes |
|---|---|---|
| 0 | Reset | The ESP32 reset pin (inverted) |
| 13 | I2C Sniffer SDA | Defined in i2c_sniffer.h |
| 14 | I2C Slave SDA | Defined in i2c_slave.h |
| 15 | DHT22 I/O | Defined in dht.h |
| 25 | I2C Sniffer SCL | |
| 26 | I2C Master SCL | Defined in i2c_master.h |
| 27 | I2C Master SDA | |
| 33 | I2C Slave SCL |
The I2C pins were carefully chosen so that they can be wired into a "bus", as can be seen on the schematic:
The Itho mainboard is an I2C master running at ~100kHz.
Each packet has a checksum byte at the end, which is the negative sum of all other bytes.
First byte is destination address (0x82 = Itho mainboard).
Second byte is reply address (0x80 = dongle).
2 bytes: message code.
1 byte: message flags (it seems: 06 = write, 04 = request, 01 = reply).
1 byte: payload length (N).
N bytes: payload.
1 byte: checksum.
82 80 90 E0 04 00 8A
Example reply:
80 82 90 E0 01 12 00 01 00 03 12 0B 00 00 00 FF FF FF FF FF FF FF FF 00 62
00 = Manufacturer (Itho), 03 = Device type (HRU), 12 = HW version, 0B = list version.
The "list version" refers to the Datalabel_V.. table in the corresponding Jet DB (.par) file of the Servicetool.
Some known Device Type codes:
01 : Lucht gordijn
03 : HRU ECO-fan
08 : Laadboiler
0A : Gas gestookte boost boiler
0B : DemandFlow
0C : CO2 relay
0D : Warmtepomp
0E : Oplaadboiler enkele wisselaar
0F : AutoTemp
10 : Oplaadboiler dubbele wisselaar
11 : RF+
14 : CVE
15 : Extended
16 : Extended Plus
1A : AreaFlow
1B : CVE-Silent
1C : CVE-SilentExt
1D : CVE-SilentExtPlus
20 : RF_CO2
2B : HRU 350
82 80 90 E1 04 00 89
Example reply (edited):
80 82 90 E1 01 03 52 D3 3C 48
Serial nr: 52D33C = 5428028
82 80 A4 00 04 00 56
Example reply:
80 82 A4 00 01 16 91 11 10 90 10 90 92 92 00 92 92 00 00 91 00 10 10 00 90 00 00 10 C8
A4 00 01 followed by number of data elements, followed by element formats (1 byte per element).
Data format (1 byte):
| Bit | Description |
|---|---|
| 7 | signed (1) / unsigned (0) |
| 6..4 | size in bytes (2^n): 0=1, 1=2, 2=4 |
| 3..0 | decimal digits (divider 10^n) |
So for example 91 would mean "signed, 2 bytes, 0.1 values".
Special cases:
0C: unsigned 1 byte
0F: unsigned 1 byte * 0.5
5B: unsigned 2 bytes
6C: 1 byte boolean
82 80 A4 01 04 00 55
Example reply:
80 82 A4 01 01 25 00 00 03 9C 03 9E 03 98 03 EB 03 EB 09 09 09 8A 00 09 09 09 8A 00 00 0B B8 01 00 00 00 B1 79 00 00 00 00 10 95 9F
80 82 A4 01 01 followed by data size and data formatted according to the status format (see previous message).
The temperatures are the bytes 09 09 09 8A, or (0x0909 and 0x098A) 23.13 C en 24.42 C respectively (.01 values).
The first 00 00 is the ventilation level. It goes from 0 for position "1" to 03E8 (100.0) for level "3".
For the meaning of each data element refer to Itho Data Labels.xlsx
Button 1:
82 60 C1 01 01 11 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 22 F1 03 00 02 04 (2b: seq) (1b: checksum)
Button 2:
82 60 C1 01 01 11 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 22 F1 03 00 03 04 (2b: seq) (1b: checksum)
Button 3:
82 60 C1 01 01 11 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 22 F1 03 00 04 04 (2b: seq) (1b: checksum)
Button 4 (1st press):
82 60 C1 01 01 11 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 22 F3 03 00 00 0A (2b: seq) (1b: checksum)
Button 4 (2nd press):
82 60 C1 01 01 11 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 22 F3 03 00 00 14 (2b: seq) (1b: checksum)
Button 4 (3rd press):
82 60 C1 01 01 11 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 22 F3 03 00 00 1E (2b: seq) (1b: checksum)
Register an RFT (press 1+4 or 2+3):
82 60 C1 01 01 1A (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 1F C9 0C 00 22 F1 (3b: commander ID) 01 10 E0 (3b: commander
ID) (2b: seq) (1b: checksum)
Deregister an RFT (press 1+2+3+4):
82 60 C1 01 01 14 (4b: msg timestamp) (1b: msg format) (3b: commander ID) (1b: command seq nr) 1F C9 06 00 1F C9 (3b: commander ID) (2b: seq) (1b: checksum)
Notes:
- Each command is repeated 3 times with a short interval
- Note sure if my interpretation of (4b: msg timestamp), (1b: command seq nr), (2b: seq) is correct, most can be
00's but some itho devices (but not the HRU) need to have the command seq nr changed every message. - (3b: commander ID) are the 3 bytes of the device ID
- (1b: msg format) is the message format determining the fields present in the message. For standard 4 button remotes this is
16.
...