Joseph Ellsworth / Mbed 2 deprecated xj-Nucleo-F303K8-SHT75-TEST

Testing SHT75 humidity sensor on STM F303K8 board.

Dependencies:   SHT75 mbed

Fork of Nucleo-F303K8-SSD1306_OLED by Joseph Ellsworth

Sample code to test SHT75 humidity sensor using STM F303K8 board. Uses a 3.3V from board to power sensor. 10K resistor Pull-up on data. Must not be on same pins as I2C. Uses D0 for Clk and D1 for Data.

I had to modify sample code supplied by https://developer.mbed.org/users/nimbusgb/code/SHT75/ because the sensor failed to read without the softReset() and readStatus() at beginning of measurement loop. I think this is caused by the 72Mhtz speed of the F303K8 but did not attempt to fully diagnose.

The readStatus() method from library seems to malfunction and always return a -1 which never changes even when sensor is unplugged.

See https://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity_Sensors/Sensirion_Humidity_Sensors_SHT7x_Datasheet_V5.pdf section 2.1 for wiring.

main.cpp

Committer:
joeata2wh
Date:
2016-03-21
Revision:
2:dc3e84d595c3
Parent:
1:90d213185462
Child:
3:47148198f5f2

File content as of revision 2:dc3e84d595c3:

/* Example of Reading all the ADC pins PIN and display ot OLED display using
 Nucleo_F303K8 by Joseph Ellsworth CTO A2WH -  Free for all but no warranty, no promises
 Displays voltage read from first 2 ADC lines on OLED display

  Used to Drive:
   ebay part http://www.ebay.com/itm/152000005331?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
  0-96-I2C-IIC-SPI-Serial-White-OLED-LCD-LED-Display-Module-128X64
  The Datasheet.  https://www.adafruit.com/datasheets/SSD1306.pdf

  Unfortunately this part never turns on using the SSD1308 library.
  but did find that the https://developer.mbed.org/users/nkhorman/code/Adafruit_GFX/
  library works.  Unfortunately the Adafruit library doesn't include the scroll functionality.

  Using my I2C address scanner I found that it responds on Added 120 (x78) ,121 (x79)
  and when the part was unsoldered nothing responded on 120 or 121. According to
  to the page #19 (8.1.5) of the data sheet the I2C address should be 011110
  which seems to map correctly to dec=120 hex=79

 */

#include "mbed.h"
//#include "SSD1308.h"
#include "Adafruit_SSD1306.h"

//#include "mbed_logo.h"

//Pin Defines for I2C Bus
#define D_SDA                  PB_7 // specific for Nucleo-F303K8
#define D_SCL                  PB_6 // specific for Nucleo-F303K8
I2C i2c(D_SDA, D_SCL);

// Host PC Communication channels
Serial pc(USBTX, USBRX); // tx, rx

AnalogIn   pa0(PA_0);
AnalogIn   pa1(PA_1);

DigitalOut myled(LED1);
const float voltMeterARef = 3.3;

// an I2C sub-class that provides a constructed default
class I2CPreInit : public I2C
{
public:
    I2CPreInit(PinName sda, PinName scl) : I2C(sda, scl) {
        frequency(400000);
        start();
    };
};


I2CPreInit gI2C(D_SDA,D_SCL);
Adafruit_SSD1306_I2c gOled2(gI2C,PB_5);


float readPrint(AnalogIn ain, char *label)
{
    float tval = ain.read();
    float volts = tval * voltMeterARef;
    float perc = tval * 100.0;
    unsigned short  tvalu16 = ain.read_u16 ();
    printf("adc %s R=%3.3f V=%3.3f%% U16=%u\r\n",label, tval, volts, tvalu16);
    gOled2.printf("%s=%3.3fV\r\n",label,volts);
    gOled2.display();
    return tval;
}


int main()
{
    // Display with the Adafruit Library
    gOled2.printf("%ux%u OLED Display\r\n", gOled2.width(), gOled2.height());
    wait(5);
    gOled2.clearDisplay();
    while(1) {
        myled = !myled;
        gOled2.clearDisplay();
        gOled2.setTextCursor(1,1);
        readPrint(pa0, "PA_0");
        wait(0.1);
        gOled2.setTextCursor(1,10);
        readPrint(pa1, "PA_1");
        wait(3.0);
    }


}