hobbielektronika / Mbed 2 deprecated 06_i2c_tcn75

Read temperature from a TCN75 (or LM75) I2C thermometer

Dependencies:   mbed

06_i2c_tcn75

Read temperature from a TCN75 (or LM75) I2C thermometer. I2C address: 1 0 0 1 A2 A2 A0

Hardware requirements:

  • FRDM-KL25Z board
  • TCN75 (or LM75) thermometer

Wiring scheme:

TCN75FRDM-25KLZ
1. SDAD14 (PTE0)
2. SCLD15 (PTE1)
3. ALERT(not used)
4. GNDGND
5. A2GND
6. A1GND
7. A0GND
8. VCC3V3

Note: Pins SDA, SCL and Alert must be pulled up by external resistors.

/media/uploads/icserny/tcn75.png

main.cpp@0:84ce5e2a89b1, 2015-11-25 (annotated)

Committer:
icserny
Date:
Wed Nov 25 07:00:30 2015 +0000
Revision:
0:84ce5e2a89b1
First version

Who changed what in which revision?

UserRevisionLine numberNew contents of line
icserny 0:84ce5e2a89b1 1 /** 06_i2c_tcn75
icserny 0:84ce5e2a89b1 2 * Read temperature from a TCN75 (or LM75) I2C thermometer
icserny 0:84ce5e2a89b1 3 * I2C address: 1 0 0 1 A2 A2 A0
icserny 0:84ce5e2a89b1 4 *
icserny 0:84ce5e2a89b1 5 * Hardware requirements:
icserny 0:84ce5e2a89b1 6 * - FRDM-KL25Z board
icserny 0:84ce5e2a89b1 7 * - TCN75 (or LM75) thermometer
icserny 0:84ce5e2a89b1 8 *
icserny 0:84ce5e2a89b1 9 * Wiring scheme:
icserny 0:84ce5e2a89b1 10 *
icserny 0:84ce5e2a89b1 11 * TCN75 FRDM-25KLZ
icserny 0:84ce5e2a89b1 12 * -------------------------
icserny 0:84ce5e2a89b1 13 * 1. SDA D14 (PTE0 alias I2C_SDA)
icserny 0:84ce5e2a89b1 14 * 2. SCL D15 (PTE1 alias I2C_SCL)
icserny 0:84ce5e2a89b1 15 * 3. ALERT -- (not used)
icserny 0:84ce5e2a89b1 16 * 4. GND GND
icserny 0:84ce5e2a89b1 17 * 5. A2 GND
icserny 0:84ce5e2a89b1 18 * 6. A1 GND
icserny 0:84ce5e2a89b1 19 * 7. A0 GND
icserny 0:84ce5e2a89b1 20 * 8. VCC 3V3
icserny 0:84ce5e2a89b1 21 */
icserny 0:84ce5e2a89b1 22
icserny 0:84ce5e2a89b1 23 #include "mbed.h"
icserny 0:84ce5e2a89b1 24 I2C i2c(I2C_SDA, I2C_SCL); // Arduino compatible pins
icserny 0:84ce5e2a89b1 25 const int addr = 0x90; // TCN75 adress: 0x48<<1
icserny 0:84ce5e2a89b1 26
icserny 0:84ce5e2a89b1 27 int main()
icserny 0:84ce5e2a89b1 28 {
icserny 0:84ce5e2a89b1 29 char cmd[2]; // data buffer
icserny 0:84ce5e2a89b1 30 printf("\r\nTCN75 I2C thermometer\r\n");
icserny 0:84ce5e2a89b1 31 cmd[0] = 0x01; // Pointer to CONFIG register
icserny 0:84ce5e2a89b1 32 cmd[1] = 0x00; // Data for CONFOG register (Normal operation, comparator mode)
icserny 0:84ce5e2a89b1 33 i2c.write(addr, cmd, 2); // Send Address/comman and two bytes
icserny 0:84ce5e2a89b1 34 while (1) {
icserny 0:84ce5e2a89b1 35 wait(1);
icserny 0:84ce5e2a89b1 36 cmd[0] = 0x00; // Pointer to TEMP register
icserny 0:84ce5e2a89b1 37 i2c.write(addr, cmd, 1); // Write adress/command byte, then register address
icserny 0:84ce5e2a89b1 38 i2c.read(addr, cmd, 2); // Read 2 bytes from TEMP register
icserny 0:84ce5e2a89b1 39 float temp = cmd[0]<<8|cmd[1];
icserny 0:84ce5e2a89b1 40 printf("Temperatue = %.2f C\r\n", temp/256);
icserny 0:84ce5e2a89b1 41 }
icserny 0:84ce5e2a89b1 42 }