You cannot select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

9.1 KiB

Raw Blame History Unescape Escape

Raspberry zero config

SSH over USB

With the micro SD card ready we can now plug the USB cable to our host and Pi Zero. However, note that while the Pi Zero has two micro USB port, only one supports USB On-The-Go (OTG). It is this feature that will allows us to treat the connection as an Ethernet connection. The port in question is the innermost one, the one closer to the center of the board, as shown in the image below.

Set USB Gadget mode

We would like to be able to access the Pi Zero through SSH from our machine using a USB cable. To do that we will have to edit two files.

First, edit the file /config.txt and append this line at the end:

dtoverlay=dwc2

Second, we will edit the file /cmdline.txt. After rootwait, we will add

modules-load=dwc2,g_ether

pay attention to leave only one space between rootwaitand the new text otherwise it might not be parsed correctly.

Note that there might already be some text after rootwait in which case you still must add the following immediately after rootwait! Again, leave a single space after rootwait but also after g_ether.

The Pi Zero is fully configured, we can now configure our host.

Now create an empty file called ssh in the root directory

Configure the Rasp’s Wifi

Another option is just to get your Rasberry Pi to connect your Wi-Fi network, create wpa_supplicant.conf file in the root directory of the SD card memory.

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=<Insert 2 letter ISO 3166-1 country code here>

network={
 ssid=“<Name of your wireless LAN>”
 psk=“<Password for your wireless LAN>”
}

— My configuration for house:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=MX

network={
 ssid=“Haus_2.4G”
 psk=“7476Haus#CB2040$”
}

GL-SFT1200-869 goodlife

— and ping to your Raspberry Pi Zero by:

ping raspzero.local

—

raspzero
gmarx
Pi7476

Pendings:

Check if the Anavi example use wich package
Check the HTU21D c example to get access to the raspberryport configuration by executing the ./HTU21d output file
Upload the precompiled package to configure raspberry
Take care of the WiringPi package??
Modify the htu21d example to return a json file to use in the UI

General procedure

Install packages requirements
Install/Build WiringPi
Compile the sensors exacutables

Device preconfiguration

In irdoer to donwload and install gitgub/git packages we need to install the next packages:

sudo apt update
sudo apt upgrade -y
sudo apt install git build-essential
sudo apt install python3-smbus i2c-tools

The next step is no longer require:

no wpa_supplicant.conf and ssh files require

Enable i2c interface

sudo raspi-config
sudo i2cdetect -y 1

The anavi example

Some code examples for the sensors provided by anavi are located here: GitHub - AnaviTechnology/anavi-examples: Examples for getting started and testing ANAVI Internet of Things and add-on boards HAT & pHAT for Raspberry Pi

However, to use these example for sensors the WiringPi package is required. The package is no loger supported and you need to clone, build, and install it manually.

Wiringpi

https://github.com/WiringPi/WiringPi

short answer:
wrong.

long answer:
wiringPi is not deprecated, it’s just not maintained by G.Henderson any more but still maintained by the community on github.
The last apt package was for Pi3B+/Buster, for Pi4 it’s on github to download:

https://github.com/WiringPi/WiringPi

install:
git clone https://github.com/WiringPi/WiringPi
cd WiringPi
./build debian
ls debian-template/*deb

when you already have an old apt-package and want to upgrade by gitclone, then 1st of all better make a clean uninstall of the old one.

My own header files

This is a detailed guide to configure and create your own files to comunicate with each sensor used by the air-quality sensor.

Enable I2C pheripherical

HTU21D

Header

Create the Header File htu21d.h with Header Guard and Includes:

#ifndef HTU21D_H
#define HTU21D_H

// I2C Address
#define HTU21D_I2C_ADDR 0x40
// Commands
#define HTU21D_TEMP 0xE3
#define HTU21D_HUMID 0xE5
#define HTU21D_RESET 0xFE


// Function declarations:

// Temp
int getTemperature(int fd, double *temperature);
// Humidity
int getHumidity(int fd, double *humidity);

#endif // HTU21D_H

Implement the Sensor Communication `htu21d.c`

#include <unistd.h> //to send commands to and receive from I2C device
#include <sys/ioctl.h>//setting up and controlling the I2C device settings
#include <linux/i2c-dev.h>//definitions for system calls and structures specific to I2C
#include <i2c/smbus.h>//SMBus commands in a more standardized way for I2C
#include <stdio.h>//perror

#include “htu21d.h” // my own header file

// Reset function:
int reset(int fd)
{
        if(0 > ioctl(fd, I2C_SLAVE, HTU21D_I2C_ADDR))
        {
                perror(“Failed to open the bus”);
                return -1;
        }
        i2c_smbus_write_byte(fd, HTU21D_RESET);
        return 0;
}

// Get temperature:
int getTemperature(int fd, double *temperature)
{
        reset(fd);
        char buf[3];
        __s32 res = i2c_smbus_read_i2c_block_data(fd, HTU21D_TEMP,3,buf);
        if(res<0)
        {
                perror(“Failed to read from the device”);
                return -1;
        }
        *temperature = -46.85 + 175.72 * (buf[0]*256 + buf[1]) / 65536.0;
        return 0;
}


// Get humidity:
int getHumidity(int fd, double *humidity)
{
        reset(fd);
        char buf[3];
        __s32 res = i2c_smbus_read_i2c_block_data(fd, HTU21D_HUMID, 3, buf);
        if(res<0)
        {
                perror(“Failed to read from the device”);
                return -1;
        }
        *humidity = -6 + 125 * (buf[0]*256 + buf[1]) / 65536.0;
        return 0;
}

Using the library

Now let us use the library files to implement an example of its usage(main.c):

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>

#include “htu21d.h”

int main()
{
        char filename[20];
        snprintf(filename, 19, “/dev/i2c-%d”, 1);
        int fd = open(filename, O_RDWR);
        if (0 > fd)
        {
                fprintf(stderr, “ERROR: Unable to access HTU21D sensor module: %s\n”, strerror (errno));
                exit(-1);
        }

        // Retrieve temperature and humidity
        double temperature = 0;
        double humidity = 0;
        if ( (0 > getHumidity(fd, &humidity)) || (0 > getTemperature(fd, &temperature)) )
        {
                fprintf(stderr, “ERROR: HTU21D sensor module not found\n”);
                exit(-1);
        }

        // Print temperature and humidity on the screen
        printf(“HTU21D Sensor Module\n”);
        printf(“%5.2fC\n”, temperature);
        printf(“%5.2f%%rh\n”, humidity);

        return 0;
}

was missing the stdio.hin htu21d.cimplementaion file

gcc -o example main.c htu21d.c -lbcm2835
htu21d.c: In function ‘reset’:
htu21d.c:13:3: warning: implicit declaration of function ‘perror’ [-Wimplicit-function-declaration]
   13 |   perror(“Failed to open the bus”);
      |   ^~~~~~
htu21d.c: In function ‘getTemperature’:
htu21d.c:21:48: error: expected declaration specifiers before ‘a’
   21 | int getTemperature(int fd, double *temperature)a
      |                                                ^
htu21d.c:38:1: error: expected ‘=‘, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{‘ token
   38 | {
      | ^
htu21d.c:51: error: expected ‘{‘ at end of input
   51 |
      |

Then to properly compile whiout a make file:

gcc -o example main.c htu21d.c -li2c

gcc -o example main.c htu21d.c -I. -li2c

Wiring htu21d to Rasp-zero

Htu -> Rasp-Zero VIN -> GPIO 1 GND -> GPIO 9 or (6) SCL -> GPIO 5 SDA -> GPIO 3

BMP180

sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         — — — — — — — —
10: — — — — — — — — — — — — — — — —
20: — — — — — — — — — — — — — — — —
30: — — — — — — — — — — — — — — — —
40: 40 — — — — — — — — — — — — — — —
50: — — — — — — — — — — — — — — — —
60: — — — — — — — — — — — — — — — —
70: — — — — — — — 77

MHZ19

Enable serial iterface

sudo raspi-config

Testing MHZ with python

sudo apt install python3-pip
sudo pip3 install mh-z19

https://chat.openai.com/share/61ea4fa0-29ff-4569-9fdc-36dd4c4c7a30

9.1 KiB Raw Blame History Unescape Escape