projects / sigrok-dumps.git / blame
| Commit | Line | Data |
|---|---|---|
| f68fd2bd KK |
1 | ------------------------------------------------------------------------------- |
| 2 | Dallas DS18B20 1-Wire digital temperature sensor | |
| 3 | ------------------------------------------------------------------------------- | |
| 4 | ||
| 5 | This is a set of example captures of the 1-Wire traffic from Maxim DS18B20 | |
| 6 | temperature sensors. | |
| 7 | ||
| 8 | Details: | |
| 9 | https://en.wikipedia.org/wiki/1-Wire | |
| 10 | https://datasheets.maximintegrated.com/en/ds/DS18B20.pdf | |
| 11 | ||
| 12 | ||
| 13 | Logic analyzer setup | |
| 14 | -------------------- | |
| 15 | ||
| 16 | The logic analyzer used was a MCU123 Saleae Logic clone (at 8 MHz): | |
| 17 | ||
| 18 | Probe DS18D20 pin | |
| 19 | ----------------------- | |
| 20 | 1 (brown) 2 (DQ) | |
| 21 | ||
| 22 | The sigrok command line used was: | |
| 23 | ||
| 24 | sigrok-cli -d fx2lafw:samplerate=1mhz --samples 2m --channels 0 -o <file> | |
| 25 | ||
| 26 | ||
| 27 | 2xds18b20.sr | |
| 28 | ------------ | |
| 29 | ||
| 30 | Two DS18D20 sensors are connected to the 1-Wire bus with following ROM codes: | |
| 31 | ||
| 32 | - 0x8d011627f794ee28 | |
| 33 | (family code: 0x28, serial number: 0x011627f794ee, CRC: 0x8d) | |
| 34 | - 0x330216255487ee28 | |
| 35 | (family code: 0x28, serial number: 0x0216255487ee, CRC: 0x33) | |
| 36 | ||
| 37 | The sensors have the same following marking: | |
| 38 | ||
| 39 | Dallas | |
| 40 | 18B20 | |
| 41 | 1619C4 | |
| 42 | +827AH | |
| 43 | ||
| 44 | The communication is initiated by a custom 1-Wire master software | |
| 45 | implementation for a STM32F103C8 using timers. | |
| 46 | ||
| 47 | The master performs the following actions: | |
| 48 | ||
| 49 | - Use Search ROM command to enumerate all 1-Wire devices on the bus so to | |
| 50 | count the number of DS10B20 sensors on the bus (two). | |
| 51 | - Restart enumeration of each device using the Search ROM command so to store | |
| 52 | their ROM code. After enumeration of each device: | |
| 53 | - Use Match ROM command to select device. | |
| 54 | - Use Read Scratchpad function command to read the 9 scratchpad bytes. | |
| 55 | - Use Write Scratchpad function command to write 3 bytes, setting the | |
| 56 | temperature conversion precision to 9 bits. | |
| 57 | - Use the Copy Scratchpad function command to copy the scratchpad into | |
| 58 | the device's internal EEPROM. | |
| 59 | - Use Skip ROM command to address all devices. | |
| 60 | - Use Convert T function command to start temperature conversion. | |
| 61 | - After one second use Match ROM and Read Scratchpad commands on each device | |
| 62 | to read the temperature stored in the scratchpad. | |
| 63 | - After 1 second use Skip ROM and Convert T commands to start next conversion. |