Seeed / Grove_Node

The firmware of the Grove Node

Dependencies:   BLE_API color_pixels mbed-src-nrf51822 nRF51822

Fork of BLE_LoopbackUART by Bluetooth Low Energy

udriver/temperature_sensor.cpp@10:f34ff4e47741, 2015-06-04 (annotated)

Committer:
yihui
Date:
Thu Jun 04 09:34:13 2015 +0000
Revision:
10:f34ff4e47741
0.01 - sync input & output with android app

Who changed what in which revision?

UserRevisionLine numberNew contents of line
yihui 10:f34ff4e47741 1
yihui 10:f34ff4e47741 2 #include "udriver.h"
yihui 10:f34ff4e47741 3 #include "mbed.h"
yihui 10:f34ff4e47741 4
yihui 10:f34ff4e47741 5 int temperature_sensor_init(void *obj, void *params)
yihui 10:f34ff4e47741 6 {
yihui 10:f34ff4e47741 7 int pin = *(int *)params;
yihui 10:f34ff4e47741 8 *(AnalogIn **)obj = new AnalogIn((PinName)pin);
yihui 10:f34ff4e47741 9
yihui 10:f34ff4e47741 10 return 0;
yihui 10:f34ff4e47741 11 }
yihui 10:f34ff4e47741 12
yihui 10:f34ff4e47741 13
yihui 10:f34ff4e47741 14 int temperature_sensor_read(void *obj, void *data)
yihui 10:f34ff4e47741 15 {
yihui 10:f34ff4e47741 16 const uint32_t beta = 3975;
yihui 10:f34ff4e47741 17 float a;
yihui 10:f34ff4e47741 18 float temperature;
yihui 10:f34ff4e47741 19 float resistance;
yihui 10:f34ff4e47741 20 AnalogIn *probe = *(AnalogIn **)obj;
yihui 10:f34ff4e47741 21
yihui 10:f34ff4e47741 22 a = probe->read();
yihui 10:f34ff4e47741 23
yihui 10:f34ff4e47741 24 /* Calculate the resistance of the thermistor from analog votage read. */
yihui 10:f34ff4e47741 25 resistance = (float) 10000.0 * ((1 / a) - 1);
yihui 10:f34ff4e47741 26
yihui 10:f34ff4e47741 27 /* Convert the resistance to temperature using Steinhart's Hart equation */
yihui 10:f34ff4e47741 28 temperature = (1/((log(resistance/10000.0)/beta) + (1.0/298.15)))-273.15;
yihui 10:f34ff4e47741 29
yihui 10:f34ff4e47741 30 *(float *)data = temperature;
yihui 10:f34ff4e47741 31
yihui 10:f34ff4e47741 32 return 0;
yihui 10:f34ff4e47741 33 }
yihui 10:f34ff4e47741 34
yihui 10:f34ff4e47741 35 int temperature_sensor_write(void *obj, void *data)
yihui 10:f34ff4e47741 36 {
yihui 10:f34ff4e47741 37 return 0;
yihui 10:f34ff4e47741 38 }
yihui 10:f34ff4e47741 39
yihui 10:f34ff4e47741 40 int temperature_sensor_fini(void *obj)
yihui 10:f34ff4e47741 41 {
yihui 10:f34ff4e47741 42 AnalogIn *ptr = *(AnalogIn **)obj;
yihui 10:f34ff4e47741 43 delete ptr;
yihui 10:f34ff4e47741 44
yihui 10:f34ff4e47741 45 return 0;
yihui 10:f34ff4e47741 46 }
yihui 10:f34ff4e47741 47
yihui 10:f34ff4e47741 48 driver_t temperature_sensor_driver =
yihui 10:f34ff4e47741 49 {
yihui 10:f34ff4e47741 50 .init = temperature_sensor_init,
yihui 10:f34ff4e47741 51 .read = temperature_sensor_read,
yihui 10:f34ff4e47741 52 .write = temperature_sensor_write,
yihui 10:f34ff4e47741 53 .fini = temperature_sensor_fini,
yihui 10:f34ff4e47741 54
yihui 10:f34ff4e47741 55 .d = 1,
yihui 10:f34ff4e47741 56 };