mraa | Linux Library for low speed IO Communication

I am using Yocto project cross-compiler to compile my C code.

But for some reasons I have compilation errors.

This is my C code :

This is my i2c sensor: http://www.mindsensors.com/rpi/76-smartdrive-high-current-motor-controller look in pdf in Documents sessions please

Based on this google guide https://developer.android.com/things/sdk/pio/pio-cli.html What I need to put in XX ZZ YY UU to run motors in determined speed, direction, duration, etc...

e.g.: pio i2c I2C1 0x1B write-reg-buffer 0xXX 0xYY 0xUU 0xZZ

As (in this case) I will use writeRegBuffer() on my android things app to run one, two or both motors in determined spped, direction, duration, etc?

e.g.: I used (via jcenter) this driver in intel edison/android things DP2, but now I want to create an AT driver to use smartdrive in nx pico and rpi 3, because there would be no more mraa:

https://github.com/androidthings/contrib-drivers/issues/70

My questions is: If you see here: https://github.com/intel-iot-devkit/upm/blob/master/src/smartdrive/smartdrive.hpp and especially in this: https://github.com/intel-iot-devkit/upm/blob/master/src/smartdrive/smartdrive.cxx in function

I am working with a Raspberry Pi Zero that is my server, running my module.

Raspberry's are not the best to compile code so I want to compile the server-side code locally. To do so I need to compile the code without resolving my imports. Why that ?

Because the Server module uses other modules that can only be installed on the Raspberry (such as UPM or MRAA for sensors).

For now I compile on the Pi but it's slow.

So I'm trying to compile to ES6 locally with my config:

I am trying to test the i2c communication of the MAX77651 chip before programming it.

So here is my setup to do so:

I have an UMFT4222ev connected to my Linux laptop by USB. This chip has his SCL and SDA linked to the SDA and SCL of my MAX77651 thanks to the Evaluation Kit for the MAX77651. My MAX77651evkit is powered with 3,7V on the Vbatt pin.

I also installed the mraa librarie from git hub and the libft4222. I know mraa is well installed because i tried it with and example.

I was told that the mraa library takes in charge the setup of the FT4222 so i only used mraa functions to make my program.

I searched on the website of Maxim integrated the i2c slave address and one register where i could read data and check if everyting is working. I then read the i2c protocol of communication to read a single register which is available here : https://datasheets.maximintegrated.com/en/ds/MAX77650-MAX77651.pdf at the page 78.

With all those informations I tried to make my "test program". I solved the compiling errors but when I execute the program I can't get what is in the register which should be 0xFF.

Here is my program:

I created a quick & dirty prototype in Python that reads temperature/humidity from an HTU21D sensor sensor that's connected to an Intel Edison. I'm trying to rewrite the Python prototype in Java. Unfortunately, the values being returned for temperature/humidity in Java are zero.

The code is posted on Github: https://github.com/alexwoolford/htu21d_logger. Under the covers, both Python and Java versions are using upm/mraa.

Here's the Java code to read from the sensor:

My question is in relation to .so shared libraries. I am building a project that uses cmake on one ubuntu machine but running the application on another ubuntu machine.

In the CMakeLists.txt file, I have the following lines:

I'm setting up some basic database hashing, but upon setup I'm receiving a 400 bad request.

This is my first time using hashes and I could use some advice. I don't plan on salting the hashes. is there something I'm missing on the HTML side?

Some time ago I was connecting DHT11 sensor to Arduino UNO and wrote a simple library based on the one from Arduino website.

At the moment I'd like to connect DHT11 to Intel Edison with Arduino Expansion Board running Yocto Linux. While trying to rewrite the library to Python I expected a problem with microseconds's sleeps in that language and finally decided to remake Raspberry Pi DHT11 Library using mraa. However, sensor isn't working as well. I found the topic on Intel forum blaming Edison ports fast IN/OUT switching inability. The proposed solution using two wires also didn't help me.

After this introduction, a few questions come to my mind:

1. Since both Raspberry and Edison are computer systems with real processors and Linux (unlike the Arduino which consists of simple microcontroller), why are people facing a problem with DHT11 on Edison, while those who are using Raspberry aren't?

2. What is the source of those problems? Is it connected with non-deterministic OS timing on Edison (RPi has the same, hasn't it?), with digital pins flaw or both?

3. Is it even possible to solve this using two wires (alternatively with a diode)? Maybe it's impossible without a suggested tri-state buffer?

4. What is the simplest way to connect one-wire devices to Edison?

Could somebody explain the difference to me between 'installing' a library from a PPA on Ubuntu and compiling a library from source?

For example - Intel have a library called MRAA for accessing platform IO in linux.

You can install the library from a PPA (which works for me) or you can compile it.

Intel MRAA library

How does installing remove the need for compiling?