frederic blanc
SHT V4 5V UART
Fork of
SHT_v1
by 
Stephen McGarry
Revision 1:0dbbb4802508, committed 2016-02-23
- Comitter:
- fblanc
- Date:
- Tue Feb 23 08:10:54 2016 +0000
- Parent:
- 0:df1c8f2961a1
- Commit message:
- SHT V4 5V;
Changed in this revision
--- a/SHT.cpp Sun Jan 24 22:00:35 2010 +0000
+++ b/SHT.cpp Tue Feb 23 08:10:54 2016 +0000
@@ -6,6 +6,7 @@
#include "SHT.h"
#include "mbed.h"
+#define MICROSECONDE 10//1
SHT::SHT(PinName p_sclk, PinName p_data, SHT_acc p_accuracy) : sclk(p_sclk), data(p_data), accuracy(p_accuracy) {
sclk=0;
@@ -13,7 +14,7 @@
data.mode(PullUp); // with the pull up internally active
data.input(); // with line released to go high
temperature = humidity = dewpoint=0.0f;
- printf("constructor\n");
+
}
char SHT::write_byte(byte value)
@@ -26,16 +27,17 @@
for (i=0x80;i>0;i/=2) { //shift bit for masking
if (i & value) data.input(); //masking value with i , write to SENSI-BUS
else data.output();
- wait_us(1); //ensure sclk is low for min time
+ wait_us(MICROSECONDE); //ensure sclk is low for min time
+
sclk=1; //clk for SENSI-BUS
- wait_us(1); //pulsewith approx. 2 us
+ wait_us(MICROSECONDE); //pulsewith approx. 2 us
sclk=0;
}
data.input(); //release DATA-line
- wait_us(1); //ensure sclk is low for min time
+ wait_us(MICROSECONDE); //ensure sclk is low for min time
sclk=1; //clk #9 for ack
error=data; //check ack (DATA will be pulled down by SHT11)
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=0;
return error; //error=1 in case of no acknowledge
}
@@ -47,16 +49,16 @@
byte i,val=0;
data.input(); //release DATA-line
for (i=0x80;i>0;i/=2) { //shift bit for masking
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=1; //clk for SENSI-BUS
if (data) val=(val | i); //read bit
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=0;
}
- wait_us(1);
+ wait_us(MICROSECONDE);
if (send_ack) data.output(); // if ack needed then drive data low
sclk=1; //clk #9 for ack
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=0;
data.input(); //release DATA-line
return val;
@@ -72,19 +74,19 @@
{
data.input();
sclk=0; //Initial state
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=1;
- wait_us(1);
+ wait_us(MICROSECONDE);
data.output(); // data low
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=0;
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=1;
- wait_us(1);
+ wait_us(MICROSECONDE);
data.input(); // allow data to high
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=0;
- wait_us(1);
+ wait_us(MICROSECONDE);
}
void SHT::connection_reset(void)
@@ -99,12 +101,13 @@
data.input(); // allow data high
sclk=0; // and clk low
for (i=0;i<9;i++) { // 9 SCK cycles
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=1;
- wait_us(1);
+ wait_us(MICROSECONDE);
sclk=0;
}
}
+
char SHT::soft_reset(void)
//----------------------------------------------------------------------------------
// resets the sensor by a softreset
@@ -168,21 +171,23 @@
void SHT::calculate()
//----------------------------------------------------------------------------------------
-// calculates temperature [°C] and humidity [%RH]
+// calculates temperature [�C] and humidity [%RH]
// input : hum [Ticks] (12 bit)
// temp [Ticks] (14 bit)
// output: humidity [%RH]
-// temperature [°C]
+// temperature [�C]
{
- const float C1=-4.0; // for 12 Bit
- const float C2=+0.0405; // for 12 Bit
- const float C3=-0.0000028; // for 12 Bit
- //const float T1=+0.01; // for 14 Bit @ 5V
- //const float T2=+0.00008; // for 14 Bit @ 5V
-
+ //Optimized V4 humidity conversion coefficients
+ const float C1=-2.0468; // for 12 Bit
+ const float C2=0.0367; // for 12 Bit
+ const float C3=-1.5955E-6; // for 12 Bit
+ const float T1=0.01; // for 12
+ const float T2=0.00008; // for 12 Bit
+ const float D1= -40.1; //for °C 5V
+ const float D2= 0.01 ; //for °C for 14
float rh; // rh: Humidity [Ticks] 12 Bit
float t; // t: Temperature [Ticks] 14 Bit
- //float rh_lin; // rh_lin: Humidity linear
+ float rh_lin; // rh_lin: Humidity linear
if (accuracy==SHT_low) {
rh=hum*16; // rescale to high accuracy values - 8 to 12 bits
t=temp*4; // and 12 to 14 bits
@@ -191,9 +196,9 @@
t=temp;
}
- temperature=t*0.01 - 40; //calc. temperature from ticks to [°C]
- humidity=C3*rh*rh + C2*rh + C1; //calc. humidity from ticks to [%RH]
- // =(temperature-25)*(T1+T2*rh)+rh_lin; //calc. temperature compensated humidity [%RH] (ignore as never >0.25%)
+ temperature=D1 + D2*t ; //calc. temperature from ticks to [�C]
+ rh_lin=C3*rh*rh + C2*rh + C1; //calc. humidity from ticks to [%RH]
+ humidity =(temperature-25)*(T1+T2*rh)+rh_lin; //calc. temperature compensated humidity [%RH] (ignore as never >0.25%)
if (humidity>100)humidity=100; //cut if the value is outside of
if (humidity<0.1)humidity=0.1; //the physical possible range
}
@@ -210,9 +215,10 @@
return dewpoint;
}
-void SHT::update(SHT_acc acc) { // update stored values from sensor
+int SHT::update(SHT_acc acc) { // update stored values from sensor
int error=0;
- connection_reset();
+ soft_reset();
+ //connection_reset();
if (acc!=accuracy) {
accuracy=acc;
error+=write_status((acc==SHT_low)?0x01:0x00); //set the status reg to high or low accuarcy
@@ -220,5 +226,5 @@
error+=measure(temp,com_measure_temp);
error+=measure(hum,com_measure_humid);
if (!error) calculate();
-
+return error;
}
--- a/SHT.h Sun Jan 24 22:00:35 2010 +0000
+++ b/SHT.h Tue Feb 23 08:10:54 2016 +0000
@@ -7,6 +7,7 @@
#include "mbed.h"
+
enum SHT_acc {
SHT_low=0,
SHT_high=1
@@ -14,7 +15,7 @@
typedef unsigned char byte;
-class SHT : public Base {
+class SHT {
public:
/* Constructor: SHT
* Creates an SHT interface connected to specific pins.
@@ -27,7 +28,7 @@
float get_temperature(); // get the most recent temp reading
float get_humidity(); // get the most recent humidity reading
float get_dewpoint(); // get the most recent dewpoint value
- void update(SHT_acc accuracy); // update stored values from sensor
+ int update(SHT_acc accuracy); // update stored values from sensor
protected:
byte read_byte(bool send_ack);
--- a/main.cpp Sun Jan 24 22:00:35 2010 +0000
+++ b/main.cpp Tue Feb 23 08:10:54 2016 +0000
@@ -3,18 +3,49 @@
#include "mbed.h"
#include "SHT.h"
+const char VERSION[]="2014_11_14";
+Serial pc(USBTX, USBRX); // tx, rx
+//SHT sht(PTE2,PTE3,SHT_high); // sclock, data
+SHT sht(p19,p20,SHT_high); // sclock, data
+DigitalOut led1(LED1);
+Ticker flipper;
-SHT th1(p5,p6,SHT_high); // sclock, data
-
-DigitalOut led1(LED1);
+void flip()
+{
+ led1=!led1;
+ sht.update(SHT_high);
+}
-int main() {
- while(1) {
- th1.update(SHT_high);
- printf("t:%6.2fC h:%6.2f%%\n",th1.get_temperature(),th1.get_humidity());
- led1=!led1;
- wait(1);
+void pc_rx(void)
+{
+ char c;
+ c=pc.getc();
+ switch (c) {
+
+ case 'H':
+ case 'h':
+ pc.printf("Humdity [ %3.2f %% ]\r\n", sht.get_humidity());
+ break;
+ case 'T':
+ case 't':
+ pc.printf("Temperature [ %3.2f C ]\r\n", sht.get_temperature());
+ break;
+ case 'V':
+ case 'v':
+ pc.printf("version %s\r\n",VERSION);
+ break;
+
}
+
+}
+int main() {
+flipper.attach(&flip, 0.5);
+ while (1) {
+ if (pc.readable())
+ pc_rx();
+
+
+ }
}
--- a/mbed.bld Sun Jan 24 22:00:35 2010 +0000 +++ b/mbed.bld Tue Feb 23 08:10:54 2016 +0000 @@ -1,1 +1,1 @@ -http://mbed.org/users/mbed_official/code/mbed/builds/49a220cc26e0 +http://mbed.org/users/mbed_official/code/mbed/builds/b3110cd2dd17 \ No newline at end of file