As with the DS18B20, the DS1822 provides a 16-bit numeric value corresponding to the measured temperature.

The conversion formula is the same:

T(°C) = Brut Value / 16

🔹 Example 1 – Standard Reading

The sensor returns:

• LSB = 0xA2
• MSB = 0x00

Raw value 0x00A2 = 162₁₀ T = 162 / 16 = 10.125 °C

✅ Result: the measured temperature is ≈ 10.1 °C.

🔹 Example 2 – Negative reading

The sensor returns:

• LSB = 0x5E
• MSB = 0xFF

Raw value (two's complement):

Raw value 0xFF5E = -162₁₀ T = -162 / 16 = -10.125 °C

✅ Result: measured temperature = −10.1 °C.

🔹 Practical notes:

• Reading via “Read Scratchpad” command (0xBE).
• Resolution configured in the R1/R0 bits register.
• The data includes TH/TL alarms and the CRC for validation.

The DS1822 connects via a 1-Wire bus, similar to the DS18B20.

It operates in both normal mode (3 wires) and parasite mode (2 wires).

🔹 Typical components

     +3.3V / +5V
         │
        [4.7kΩ]
         │
DATA ────┼──────────────┐
         │              │
        GND            DS1822
                        │
                       GND

Parasitic mode (2 wires)

DATA ───┬────────────── DS1822
        │
       GND

🔹 Operating Principle

1️⃣ The 1-Wire master initializes the bus with a reset pulse.

2️⃣ The DS1822 responds with a presence pulse.

3️⃣ The "Convert T" command (0x44) initiates the conversion.

4️⃣ After the conversion delay (93–750 ms), the microcontroller reads the result with "Read Scratchpad" (0xBE).

Each DS1822 has a unique 64-bit address, structured as follows:

• 8 bits: family code (0x22 for DS1822)
• 48 bits: unique serial number
• 8 bits: CRC check

This system guarantees:

• 🔗 Simple chaining of multiple sensors on a single bus.
• 🧠 Automatic unique identification without reconfiguration.
• 🧩 Easier maintenance: identical replacement without recalibration.

Example of a unique address:

22-FF-1A-34-86-15-03-5C

✅ Each sensor can be addressed independently, even on the same shared cable.