Using  a DHT11 temperature sensor on Starter Kit MT3620

https://sadiajabeen92.wordpress.com/2016/05/02/tutorial-for-dht11-and-spi-interface-for-pi/

This one ?

/*

* Simultaneously transmit and receive a byte on the SPI.

*

* Polarity and phase are assumed to be both 0, i.e.:

* - input data is captured on rising edge of SCLK.

* - output data is propagated on falling edge of SCLK.

*

* Returns the received byte.

*/

uint8_t SPI_transfer_byte(uint8_t byte_out)

{

  uint8_t byte_in = 0;

  uint8_t bit;

  for (bit = 0x80; bit; bit >>= 1) {

  /* Shift-out a bit to the MOSI line */

  write_MOSI((byte_out & bit) ? HIGH : LOW);

  /* Delay for at least the peer's setup time */

  delay(SPI_SCLK_LOW_TIME);

  /* Pull the clock line high */

  write_SCLK(HIGH);

  /* Shift-in a bit from the MISO line */

  if (read_MISO() == HIGH)

  byte_in |= bit;

  /* Delay for at least the peer's hold time */

  delay(SPI_SCLK_HIGH_TIME);

  /* Pull the clock line low */

  write_SCLK(LOW);

  }

  return byte_in;

}

For example...

peterfenn
bwilless

Hi folks, any insights on the above question?

Some more details and explanation are welcome :-)

How to deal with this ?

You can use and M0 core for fast pooling DHT GPIO pin and send data to A7 core

PlatformIO have Arduino (named Wring) for M0 core ...

just install any DHT library for DHT and put data to uart (for debug) ... if all is OK - send this data to A7 core via mailbox

Click board Demo Repo

Recommended starting point for adding an I2C sensor to your project, is the driver code for Click boards already ported to Azure Sphere

For temperature and humidity measurement, code for the Temp&Hum Click board (based on HTS221 device from ST Micro) is provided

• Temperature accuracy is ±0.5°C for the 15 to 40°C range (±1°C across the wider the 0 to 60°C range)
• Relative Humidity accuracy is ±3.5% for the 20 to 80% range (±6% for the full 0 to 100% range)
• This sensor provides interfaces for both I2C and SPI access

To utilize this click-board library, include the https://github.com/Avnet/clickmodules repo in your project.

More detail on this topic is available in the following blog article Using MikroE Click Boards with Microsoft Sphere

Thanks Peter.

Is there an available driver for the sensor in picture (Grove, Temperature and Humidity v1.2) ?

MikroE Click Boards are quite difficult to find compared to grove sensors, some suggestions about how to use this sensor (Grove sensors are officially supported by the AVNET MT3620) are really appreciated.
Waiting for your answer

Alessandro

It should be possible to do this without the need for any additional hardware.

It looks like the Grove connector is configured for i2C and shared with the LSM6DSO sensor (just spotted your comment that you got that already)

So you might be better connecting the DHT11 to one of spare I/O pins via the headers meant for the click sockets such as "PWM" on Click1 which is GPIO0_PWM0

https://www.avnet.com/opasdata/d120001/medias/docus/196/Azure%20Sphere%20Starter%20Kit%20User%20Guide%20(v1.3).pdf

I find these kind of cables are good for that.

Many of the arduino libraries for the DHT11/DHT22 seem to support multiple version of the sensor / boards which makes them harder to port to a different platform

Here's a basic one which might be easier to port.

https://playground.arduino.cc/Main/DHT11Lib/

Looking at the DHT11 data sheet, the one wire protocol used by the DHT11 is open drain with a pull up resistor. The seeed grove module appears to have that 5K resistor already in place (with an additional capacitor between the power rails, which we can ignore).

So when opening the pins you can set the output mode as follows:

GPIO_OpenAsOutput(mypin,GPIO_OutputMode_OpenDrain, GPIO_Value_High)

That means you can avoid the need to keep toggling the pin between input and output.

You'll need to swap the various API calls:

digitalWrite becomes GPIO_SetValue

digitaRead becomes GPIO_GetValue

delayMicroseconds becomes nanosleep (found in time.h) and scale the value by 1000

Use a scope to check the timing, the defaults might need tweeking.

Let me know how you get on.