DS18B20 Digital Temperature Sensor Features and Code Guide

1. Temperature Sensor Team Members: Jiaxiong Chen Yi Lu Changpeng Ti EE587 Apr. 17, 2009

2. Features Dallas Semiconductor DS18B20 Unique 1-Wire interface Digital temperature output Measures temperatures from -55C to +125C Power supply range is 3.0V to 5.5V

3. PIN Descriptions

4. Circuit Diagram

5. Temperature Data Format

6. Memory Map

7. Transaction Sequence Initialization Skip ROM Command (CCh) Function Command (followed by data exchange)

8. Function Commands

9. Code: ReadTemperature() void ReadTemperature() { unsigned char a,b; Init(); Skip_ROM(); Convert_T(); Init(); Skip_ROM(); Read_Scratchpad(); [a,b] = Recv_2_chars(); LT = Lower 4 digits of a; HT = Lower 4 digits of b + Higher 4 digits of a; }

10. Code: WriteUser() void WriteUser(unsigned char x,y) { unsigned char a,b,c,d; Init(); Skip_ROM(); Write_Scratchpad(); write(x); write(y); Init(); Skip_ROM(); Copy_Scratchpad(); }

11. Code: ReadUser() void ReadUser() { unsigned char a,b,c,d; Init(); Skip_ROM(); Recall_E2(); Init(); Skip_ROM(); Read_Scratchpad(); [a,b,c,d] = Recv_4_chars(); U1 = c; U2 = d; }

12. Validation Result: Code: WriteUser(80, -40); Run time: 13ms ReadUser(); Run time: 9ms ReadTemperature(); Run time: 8ms

13. Thank You !