J M / MCP9808

MCP9808 Digital temperature sensor

MCP9808.cpp@2:4f8e1fb852d3, 2017-01-20 (annotated)

Committer:
Jmfox24
Date:
Fri Jan 20 19:48:45 2017 +0000
Revision:
2:4f8e1fb852d3
Parent:
0:f06580426072 
add sensor detection function

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Jmfox24 0:f06580426072 1 #include <stdint.h>
Jmfox24 0:f06580426072 2 #include "mbed.h"
Jmfox24 0:f06580426072 3 #include "MCP9808.hpp"
Jmfox24 0:f06580426072 4
Jmfox24 0:f06580426072 5 MCP9808::MCP9808(PinName sda, PinName scl, int addr) :
Jmfox24 0:f06580426072 6 _i2c(sda, scl), _addr(addr) {}
Jmfox24 0:f06580426072 7
Jmfox24 0:f06580426072 8 MCP9808:: ~MCP9808() {}
Jmfox24 0:f06580426072 9
Jmfox24 2:4f8e1fb852d3 10 bool MCP9808::is_detected()
Jmfox24 2:4f8e1fb852d3 11 {
Jmfox24 2:4f8e1fb852d3 12 uint16_t v = 0;
Jmfox24 2:4f8e1fb852d3 13
Jmfox24 2:4f8e1fb852d3 14 /* check MFG ID */
Jmfox24 2:4f8e1fb852d3 15 if (reg_read(MCP9808_REG_MFG_ID, &v)) {
Jmfox24 2:4f8e1fb852d3 16 return false;
Jmfox24 2:4f8e1fb852d3 17 }
Jmfox24 2:4f8e1fb852d3 18 if (v != MCP9808_MFG_ID) {
Jmfox24 2:4f8e1fb852d3 19 return false;
Jmfox24 2:4f8e1fb852d3 20 }
Jmfox24 2:4f8e1fb852d3 21
Jmfox24 2:4f8e1fb852d3 22 /* check DEV ID */
Jmfox24 2:4f8e1fb852d3 23 if (reg_read(MCP9808_REG_DEV_ID, &v)) {
Jmfox24 2:4f8e1fb852d3 24 return false;
Jmfox24 2:4f8e1fb852d3 25 }
Jmfox24 2:4f8e1fb852d3 26 if (v != MCP9808_DEV_ID) {
Jmfox24 2:4f8e1fb852d3 27 return false;
Jmfox24 2:4f8e1fb852d3 28 }
Jmfox24 2:4f8e1fb852d3 29
Jmfox24 2:4f8e1fb852d3 30 return true;
Jmfox24 2:4f8e1fb852d3 31 }
Jmfox24 2:4f8e1fb852d3 32
Jmfox24 0:f06580426072 33 int MCP9808::sleep()
Jmfox24 0:f06580426072 34 {
Jmfox24 0:f06580426072 35 return set_cfg_flag(MCP9808_CFG_FLAG_SHDN_ENABLED, true);
Jmfox24 0:f06580426072 36 }
Jmfox24 0:f06580426072 37
Jmfox24 0:f06580426072 38 int MCP9808::wake()
Jmfox24 0:f06580426072 39 {
Jmfox24 0:f06580426072 40 return set_cfg_flag(MCP9808_CFG_FLAG_SHDN_ENABLED, false);
Jmfox24 0:f06580426072 41 }
Jmfox24 0:f06580426072 42
Jmfox24 0:f06580426072 43 float MCP9808::get_temperature()
Jmfox24 0:f06580426072 44 {
Jmfox24 0:f06580426072 45 uint16_t v = 0;
Jmfox24 0:f06580426072 46 float t = 0.0f;
Jmfox24 0:f06580426072 47
Jmfox24 0:f06580426072 48 reg_read(MCP9808_REG_TEMP, &v);
Jmfox24 0:f06580426072 49 t = v & 0x0FFF;
Jmfox24 0:f06580426072 50 t /= 16.0f;
Jmfox24 0:f06580426072 51 if (v & 0x1000) {
Jmfox24 0:f06580426072 52 t -= 256.0f;
Jmfox24 0:f06580426072 53 }
Jmfox24 0:f06580426072 54 return t;
Jmfox24 0:f06580426072 55 }
Jmfox24 0:f06580426072 56
Jmfox24 0:f06580426072 57 int MCP9808::reg_read(uint8_t reg, uint16_t *value)
Jmfox24 0:f06580426072 58 {
Jmfox24 0:f06580426072 59 uint8_t buffer[sizeof(*value)] = { reg, 0x00 };
Jmfox24 0:f06580426072 60 _i2c.write(_addr, (const char *)buffer, 1, true);
Jmfox24 0:f06580426072 61 _i2c.read(_addr, (char *)buffer, sizeof(buffer), false);
Jmfox24 0:f06580426072 62 *value = (buffer[0] << 8) | buffer[1];
Jmfox24 0:f06580426072 63 return 0;
Jmfox24 0:f06580426072 64 }
Jmfox24 0:f06580426072 65
Jmfox24 0:f06580426072 66 int MCP9808::reg_write(uint8_t reg, uint16_t value)
Jmfox24 0:f06580426072 67 {
Jmfox24 0:f06580426072 68 uint8_t buffer[] = { reg, (value >> 8), (value & 0xFF) };
Jmfox24 0:f06580426072 69 _i2c.write(_addr, (const char *)buffer, sizeof(buffer), false);
Jmfox24 0:f06580426072 70 return 0;
Jmfox24 0:f06580426072 71 }
Jmfox24 0:f06580426072 72
Jmfox24 0:f06580426072 73 int MCP9808::set_cfg_flag(uint16_t flag, bool v)
Jmfox24 0:f06580426072 74 {
Jmfox24 0:f06580426072 75 uint16_t value = 0x00;
Jmfox24 0:f06580426072 76 reg_read(MCP9808_REG_CFG, &value);
Jmfox24 0:f06580426072 77 if (v) {
Jmfox24 0:f06580426072 78 value |= flag;
Jmfox24 0:f06580426072 79 } else {
Jmfox24 0:f06580426072 80 value &= ~flag;
Jmfox24 0:f06580426072 81 }
Jmfox24 0:f06580426072 82 return reg_write(MCP9808_REG_CFG, value);
Jmfox24 0:f06580426072 83 }