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LoxoneLinkLegacyExtension1Wire.md

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1-Wire Extension (0x05)

The 1-Wire Extension supports up to 32 1-Wire devices and supports 3 different family categories:

  1. Temperature sensors: DS18S20, DS1822 and DS18B20 (Family codes 0x10, 0x22, 0x28)
  2. Smart battery monitor: DS2438 (Family code 0x26)
  3. other devices just as iButton (arrive/depart) (Family codes 0x01, 0x02, 0x04, 0x06, 0x08, 0x09, 0x0B, 0x0C, 0x0F, 0x14, 0x18, 0x1A, 0x21, 0x23, 0x24, 0x37 and 0x41)

That said, it seems the Miniserver doesn't support them all. It does seem to support the DS18S20 and the DS18B20 for temperature and DS2438 for temperature and voltage. And DS2401, DS1963S and DS1922 for iButton.

It uses a DS2480 to communicate with the 1-Wire bus.

Command Phase Dir B0 val16 val32 Description
0x1D S→E B0==0:Request 1-Wire statistics, B0==1:Reset 1-Wire statistics
0x63 S→E Family code polling cycle Set polling cycle for certain families, seem to be ignored by the 1-Wire Extension
0x64 S→E B1 != 0: force iButton update on/off via B0, B1==0: scan for 1-Wire devices

Configuration

The 1-Wire extension has its settings stored in FLASH. It is uploaded via a fragmented message with the type 0x06 from the Miniserver and updates are only send, if necessary (see 0x36 message above).

Format of the settings, which are 0x14E bytes large:

Offset Type Description
0 32-bit 0xFEEDFEED = magic to detect that the package is valid
4 16-bit Version of the settings, always 1
6 16-bit iButton polling time in ms, 0 = 100ms
8 16-bit Number of 1-Wire devices in the following table
0x0A 32 * 10 bytes Up to 32 1-Wire Identifiers, the family code is in the first byte of the 8-byte identifier. It is followed by a 16-bit polling cycle time in seconds.
0x14A 32-bit 0x00000000, filler value

Request statistics

The 1-Wire Extension collects statistic information about all known devices, especially error stats. They can be reported back, if Loxone Config requests it.

It sends 3 0x1D packages back per 1-Wire device. All packages have B0=2, except the very last one which sets B0=3 telling the Miniserver the statistics are complete. The statistics only seem to be collected for temperature sensors.

  1. val32 contains the overall packages requested
  2. val32 contains the CRC errors
  3. val32 contains the 85 Degree Problems errors

Scan for 1-Wire devices

The 1-Wire bus is polling for all devices. The first 32 are returned. If none are found, only 0x65 is send back with B0-B6 be zero.

Command Description
0x64 Device found. B0-B6 contain the first 7 bytes of the 1-Wire identifier (byte 8 is the CRC and can be reconstructed)
0x65 Last Device found. B0-B6 contain the first 7 bytes of the 1-Wire identifier (byte 8 is the CRC and can be reconstructed)

Polling

All 1-Wire devices are managed via polling and value/state changes are then reported back to the Miniserver. There is not direct communication from the Miniserver to the 1-Wire devices supported.

The following commands are send to the Miniserver:

Command Description
0x63 iButton init – previously unknown iButton detected, val32 contain the version number of the extension, val16 is zero.
0x66 Temperature and Voltage. B0:index of the 32 1-Wire devices, the rest is depended on the family type, see below
0x7A iButton sensor arrived (detected). B0-B6 contain the first 7 bytes of the 1-Wire identifier (byte 8 is the CRC and can be reconstructed)
0x7B iButton sensor departed (removed). B0-B6 contain the first 7 bytes of the 1-Wire identifier (byte 8 is the CRC and can be reconstructed)

The 0x66 command for temperature and voltage is decoded as follows:

Sensor Conversion
DS18S20 TempCelcius=B1 + B2 / 128 (B1 is a signed byte)
DS18B20 TempCelcius=B1 + B2 / 16.0 (B1 is a signed byte)
DS2438 TempCelcius=B2 + (B1>>3)/32.0 (B2 is a signed byte); VAD=(B3 + ((B4 & 0x03)<<8))/100.0; VDD=(((B5 & 0x0F) << 6) + (B4 >> 2))/100.0; VSens=(B6<<4)+(B5>>4) (B6 is a signed byte)