![](/media/cache/profiles/3b56beb4fb3143ab7f05335134909435.50x50_q85.jpg)
Variation. Temperature reading moves across x-axis with time, it is positioned in y-axis proportional to temperature as read.
Dependencies: C12832_lcd LM75B mbed
Fork of app-board-LM75B by
Diff: main.cpp
- Revision:
- 0:ce7a8546502b
- Child:
- 1:6484448034e3
diff -r 000000000000 -r ce7a8546502b main.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/main.cpp Sat Jan 16 02:41:51 2010 +0000 @@ -0,0 +1,140 @@ +/* + * NXP LM75B temperature sensor test + * www.nxp.com/pip/LM75B_2.html + * + * Expecting to use the pins 9 and 10 for I2C bus + * these pins should be pulled-up properly. + * + * The temperature read out will be shown on terminal on the PC screen. + * + * In this demo code, two LM75B devices can be driven. + * These two devices should have different I2C address setting + * using its address pins (LM75B's A0 to A2 (pins 5 to 7)). + * One LM75B should have all those pins tied to GND. + * And another should have the pin A0(pin7) pulled-up. + * + * From the software, those devices can be accessed by I2C addresses + * "0x90" and "0x92". + * It will not be as "0x90" and "0x91" because the address has + * 7 bit only and stuffed to left. So the "A0" setting become 0xX2. + * The LSB does not care because it will be set by I2C libraly when + * it transfer the data for read and write. + */ + +#include "mbed.h" +//#include "SDFileSystem.h" + +// LM75B IIC address +#define LM75B_ADDR 0x90 + +// LM75B registers +#define Conf 0x01 +#define Temp 0x00 +#define Tos 0x03 +#define Thyst 0x02 + + +DigitalOut led[] = { LED4, LED3, LED2, LED1 }; +Serial pc(USBTX, USBRX); // tx, rx + +I2C i2c( p9, p10 ); // sda, scl + + +void iic_write( char addr, char reg, char data ); +char iic_read( char addr, char reg ); +short iic_read_short( char addr, char reg ); +void iic_error( void ); + +void init_temp_sensor( char dev_num ); +float get_temp( char dev_num ); + +int main() { + int i; + + init_temp_sensor( 0 ); + init_temp_sensor( 1 ); + + while(1) { + pc.printf( " (%d) temp[0]=%6.3f, temp[1]=%6.3f(degree-C)\n", i++, get_temp( 0 ), get_temp( 1 ) ); + wait( 1 ); + } +} + +void init_temp_sensor( char dev_num ) +{ + dev_num <<= 1; + + iic_write( LM75B_ADDR | dev_num, Conf, 0x00 ); // configuration + pc.printf( "sensor[%d] : Conf register read out = 0x%02X\n", dev_num, iic_read( LM75B_ADDR | dev_num, Conf ) ); + pc.printf( "sensor[%d] : Tos register read out = 0x%04X\n", dev_num, iic_read_short( LM75B_ADDR | dev_num, Tos ) ); + pc.printf( "sensor[%d] : Thyst register read out = 0x%04X\n", dev_num, iic_read_short( LM75B_ADDR | dev_num, Thyst ) ); +} + + +float get_temp( char dev_num ) +{ + dev_num <<= 1; + + return ( (float)(iic_read_short( LM75B_ADDR | dev_num, Temp )) / 256.0 ); +} + +void iic_write( char addr, char reg, char data ) +{ + char cmd[2]; + + cmd[ 0 ] = reg; + cmd[ 1 ] = data; + + if ( i2c.write( addr, cmd, 2) ) + iic_error(); +} + +char iic_read( char addr, char reg ) +{ + char cmd; + int nack; + + cmd = reg; + + nack = i2c.write( addr, &cmd, 1); // Send command string + nack |= i2c.read( addr, &cmd, 1); // Send command string + + if ( nack ) + iic_error(); + + return ( cmd ); +} + + +short iic_read_short( char addr, char reg ) +{ + char cmd[ 2 ]; + int nack; + + cmd[ 0 ] = reg; + + nack = i2c.write( addr, cmd, 1); // Send command string + nack |= i2c.read( addr, cmd, 2); // Send command string + + if ( nack ) + iic_error(); + + return ( ((short)cmd[ 0 ]) << 8 | cmd[ 1 ] ); +} + + +void iic_error( void ) +{ + pc.printf( "I2C error\n" ); + + for ( int i = 0; i < 4; i++ ) + led[ i ] = i & 0x01; + + wait ( 0.2 ); + + for ( int i = 0; i < 4; i++ ) + led[ i ] = !(i & 0x01); + + wait ( 0.2 ); +} +