Category Archives: Hardware

Seeeduino XIAO Board

2020-06-22 admin

This article describes the Seeeduino XIAO development board

The general specifications of the card are

Characteristic	Value
CPU	ARM Cortex-M0+ CPU(SAMD21G18) running at up to 48MHz
Flash Memory	256KB
SRAM	32KB
Digital I/O Pins	11
Analog I/O Pins	11
I2C interface	1
SPI interface	1
UART interface	1
Power Led	Green
Test Led	Yellow
TX Serial Led	Blue
RX Serial Led	Blue
Power supply and downloading interface	USB Type C
Supply Voltage	3.3V/5V DC
Dimensions	20×17.5×3.5mm

As shown in the table, peculiar aspects of the board are the following

Powerful CPU: ARM® Cortex®-M0+ 32bit 48MHz microcontroller(SAMD21G18) with 256KB Flash,32KB SRAM.
Compatible with Arduino IDE and CircuitPython.
Breadboard-friendly.
As small as a thumb(20×17.5mm) for wearable devices and small projects.
Multiple development interfaces: 11 digital/analog pins, 10 PWM Pins, 1 DAC output, 1 SWD Bonding pad interface, 1 I2C interface, 1 UART interface, 1 SPI interface.

Here are the links to the Seeed wikis for configuration with Arduino and CircuitPython

Seeeduino XIAO with IDE Arduino

Seeeeduino XIAO with CircuitPython

CircuitPython is a simplified Micropython derived project for microcontrollers

CircuitPython

The board is programmed via USB Type C connection. It also offers a pad for power supply as well as the SWD (Serial Wire Debug) interface in the back part.

The board supports multiplexing pin and the same pin can be used,depending on the function that uses it, as analog, digital pin, etc.

On the upper part of the board there are two pins for resetting the board itself and for setting it in dfu mode for loading another bootloader (for example CircuitPython).

To reset or load another bootloader, connect the board via USB Type C and reset it by short-circuiting quickly the reset pins. When the orange LED starts to light up and flicker, the board is ready to load the firmware. Use this method even if the board is no longer visible on the USB port of the PC.

The board is available directly from the Seeed website

Seeeduino XIAO

In the next articles we set up the Arduino IDE for a small project with Seeeduino XIAO

Seeeduino XIAO – Arduino envinronment

About Seeed

Seeed is the IoT hardware enabler providing services over 10 years that empower makers to realize their projects and products. Seeed offers a wide array of hardware platforms and sensor modules ready to be integrated with existing IoT platforms and one-stop PCB fabrication and PCB assembly service. Seeed Studio provides a wide selection of electronic parts including Arduino Raspberry Pi and many different development board platforms Especially the Grove System help engineers and makers to avoid jumper wires problems. Seeed Studio has developed more than 280 Grove modules covering a wide range of applications that can fulfill a variety of needs.

Hardware

ESP32 Wifi-Bluetooth Module

2018-04-23 admin

In this article we describe briefly the ESP32 chip from Espressif

ESP32

This lower power SOC contains a 32 bit MCU with bluetooth and wifi modules. At the Espressif web site we can find the detailed informations about the ESP32

ESP32 Resources

The device datasheet is available in the following pdf document

ESP32 Datasheet

The ESP32 modules are available individually or in a development kits; the last system simplifies its usage as the development kit contains all the hardware to use rapidly the soc device; we are already ready to load the firmware and use the device.

On internet various web sites describe home automation or iot projects using this soc.

A reference site for the ESP32 is

esp32

At above link we can find the various development platforms utilized for the ESP32. The most relevant are

Arduino Ide

ESP32 Arduino

ESP-IDF

ESP32 IDF

Micropython

MicroPython

PlatformIO

PlatformIO

Firmware Lua

LuaNode

Lua-RTOS-ESP32

Nodemcu Development

We can buy the ESP32 modules/dev kits from various internet online websites, for example ebay

ESP32 on ebay

Different ESP32 modules are available from different vendors

Espressif esp-wroom-32

AI-Thinker esp32s

At the link

http://esp32.net/

different hardware configurations available are listed.

As development kits we report

AI-Thinker NodeMCU-32S

DoIT ESP32 Dev Kit

There are development kits based on esp32 that also integrate a LORA wireless module internally

Lora

We report for example the following

Heltec Wifi LoRa 32

TTGO LoRa32

In the next articles we’ll describe how to build firmwares and use the ESP32 MCU.

Hardware

Linkit 7688 Duo Connections

2017-07-09 admin

After the board specifications summary

Linkit 7688 and 7688 Duo Development Boards

this article describes how to connect to the board the following components that will be used later:

Micro USB OTG to the Host port
USB TTL Serial Device
5 V power supply to the port USB Power

The following diagram shows the connections to the board

The table below shows the connections between the USB TTL Serial device and the board

USB TTL Pin	Linkit Pin
RX	UART_TXD2
TX	UART_RXD2
GND	GND

In the netxt article we will show how to build the firmware for the Linkit 7688 and Linkit 7688 Duo

OpenWrt building for Linkit 7688 and 7688 Duo

Hardware

Linkit 7688 and 7688 Duo Development Boards

2017-07-09 admin

This article briefly describes the Mediatek Linkit 7688 and 7688 Duo development boards. Below the links for the two boards

Linkit 7688

Linkit 7688 Duo

The specifications of the two boards are the following

Linkit 7688

Model	Linkit Smart 7688
MPU	MT7688AN, MIPS24KEc, 580MHz
RAM	128 Mb DDR2
Flash memory	32 Mb
GPIO	22 (MT7688AN) 3,3 V
PWM	4 (MT7688AN) 3,3 V
Expernal Interrupts	22 (MT7688AN)
SPI	1 (MT7688AN)
UART Lite	3 (MT7688AN)
Power	Micro USB 5V DC or PIN 3,3 V
USB HOST	Micro USB
Ethernet	By extension
Wifi	1T1R 802.11 b/g/n (2.4G)
User storare	Micro SDSDXC sdcard
Dimensions	55.7 x 26 mm
Weight	39 grams

Linkit 7688 Duo

Model	Linkit Smart 7688 Duo
MPU	MT7688AN, MIPS24KEc, 580MHz
MCU	Atmel AVR 8MHz
RAM	128 Mb DDR2
Flash memory	32 Mb
GPIO	3 (MT7688AN) 3,3 V 24 (ATmega32U4)
PWM	8 (ATmega32U4) 3,3 V
External Interrupts	8 (ATmega32U4)
SPI	1 (ATmega32U4)
UART Lite	1 (ATmega32U4) 1 (MT7688AN)
Power	Micro USB 5V DC or PIN 3,3 V
USB HOST	Micro USB
Ethernet	By extension
Wifi	1T1R 802.11 b/g/n (2.4G)
User storage	Micro SDSDXC sdcard
Dimensions	55.7 x 26 mm
Weight	39 grams

The two boards share the same Microprocessor (MPU MT7688AN), but in the case of the Linkit 7688 Duo this MPU is supported by the Atmel Microcontroller (MCU ATmega32U4) for device management.

The interfacing schemes are shown with peripherals in the two cases below

The operating system used for both bords is OpenWrt, but the peripherals management is different. While in the case of Linkit 7688 we only rely on MPUs and specific libraries to manage the interfacing with peripherals, for the Linkit 7688 Duo the ATmega32U4 microcontroller manages the peripherals. The programming of the ATmega32U4 is executed with the Arduino IDE by adding the Linkit 7688 Duo board support into the tool as specified at the following link

Arduino Ide support for Linkit 7688 Duo

At the followning link there is the Mediatek documentation for the two boards

Linkit 7688 and 7688 Duo Resources

The following pages show how the two boards can interact with the various peripherals

Linkit 7688 peripherals

Linkit 7688 Duo peripherals

At the Mediatek site, there are also examples to follow step by step to test the various features of the development boards.

The next article shows how to connect the USB OTG cable , to use with a USB drive, an USB TTL serial cable, to monitor the device, to the board

Linkit 7688 Duo Connections

Development, Hardware, Software

MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with Relay

2017-04-01 admin

After the article about the connection with the temperature and humidity sensor

MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with temperature sensor

in this article we set the esp8266 to run a relay. Here is how we connect the relay to the ESP module

In this example too we will consider the option of putting the nodemcu in sleep. To have the node back form the sleep the system has to reboot and it is necessary to connect the PIN D0 (GPIO16) to RST PIN as specified in the nodemcu documentation

Nodemcu sleep

Let us take a look at the lua code; It consists of init.lua and relay.lua files.

We analyze now the main points of each file

init.lua

-- init.lua
SSID="SSID" -- SSID 
PASSWORD="password" -- SSID password
TIMEOUT=10000   -- timeout to check the network status
EXSENSOR1="relay.lua"   -- module to run
MQTTSERVER="mqttaddress"   -- mqtt broker address
MQTTPORT="1883" -- mqtt broker port
MQTTQOS="0" -- qos used

-- Set the netowrk parameters and get ip address
wifi.setmode(wifi.STATION)
wifi.sta.config(SSID, PASSWORD)
wifi.sta.getip()


-- Check the network status after the TIMEOUT interval
tmr.alarm(0, TIMEOUT,tmr.ALARM_SINGLE, function()
    status=wifi.sta.status()
   -- if esp8266 got the ip
   if (status == wifi.STA_GOTIP ) then

        dofile(EXSENSOR1)
        
    
    else
        -- Without up restart the node
        print("Error acquiring ip address=",status)
        node.restart()
    end


end

)

-- init.lua

SSID="SSID" -- SSID

PASSWORD="password" -- SSID password

TIMEOUT=10000 -- timeout to check the network status

EXSENSOR1="relay.lua" -- module to run

MQTTSERVER="mqttaddress" -- mqtt broker address

MQTTPORT="1883" -- mqtt broker port

MQTTQOS="0" -- qos used

-- Set the netowrk parameters and get ip address

wifi.setmode(wifi.STATION)

wifi.sta.config(SSID, PASSWORD)

wifi.sta.getip()

-- Check the network status after the TIMEOUT interval

tmr.alarm(0, TIMEOUT,tmr.ALARM_SINGLE, function()

status=wifi.sta.status()

-- if esp8266 got the ip

if (status == wifi.STA_GOTIP ) then

dofile(EXSENSOR1)

else

-- Without up restart the node

print("Error acquiring ip address=",status)

node.restart()

end

)

In the file we set the the parameters to access the wifi network, the address and port of the MQTT broker and the file to be run on the ESP after wifi connection to the access point is estabilished. If the ESP doesn’t acquire the network address the system is restarted.

relay.lua

-- relay.lua
CNAME="relay1" -- Client name 
AMBIENT="home"  -- Ambient name 
STOPIC     = AMBIENT.."/"..CNAME.."/status"  -- Status topic
CTOPIC     = AMBIENT.."/"..CNAME.."/command" --Command topic   
MTOPIC     = AMBIENT.."/"..CNAME.."/monitor" --Monitor topic


sleep_in_seconds= nil --Sleep in seconds


TUPDATE = 20 -- Time interval for update monitor in seconds
RPIN        =1 -- Relay Pin
TGEN = 5 -- Time interval in seconds usend in various trm
gpio.mode(RPIN,gpio.OUTPUT) -- Set Relay pin mode
gpio.write(RPIN,gpio.LOW) -- Default output is OFF





-- Define Client Name and connection parameters
mqt = mqtt.Client(CNAME, 60, "", "", 1) 

-- Subscribe to the topics and send status to the status topic
mqt:on("connect", function() 
    mqt:subscribe(STOPIC, MQTTQOS)
    mqt:subscribe(CTOPIC, MQTTQOS)
    mqt:subscribe(MTOPIC, MQTTQOS)
    send_status("Relay ready again")
end )

-- Callback when mqtt is offline
mqt:on("offline", function() print("mqtt offline");  end)

--Callback to manage messages 
mqt:on("message", function(client, topic, data) 
    manage_message(client, topic, data) 
end)

-- Function to filter the messages
function manage_message(client, topic, data) 
    -- If CTOPIC: command topic
    if topic == CTOPIC then

        -- If the command is Restart
        if data == "Restart" then
            send_status("Restarting")
            send_mstatus("Restarting")
            tmr.alarm(2, TGEN*1000, tmr.ALARM_SINGLE, node.restart)
        -- If the command is null    
        elseif data == nil then
            send_status("Command not valid")
        -- Command to turn on the Relay    
        elseif data == "ON" then
            relay_on()
        -- Command to turn off the Relay    
        elseif data == "OFF" then
            relay_off()  
        -- Command to check the state of the Relay    
        elseif data == "Status" then
            relay_status()         
            
        else
            -- Check the Sleep command
            i=string.len(data)
            dato=string.sub(data,1,5)

            if dato == "Sleep" then
                ndato=string.sub(data,6)
                TSLEEP=tonumber(ndato)
                if TSLEEP ~= nil then

                    if TSLEEP >= 1 then
 
                        -- Sets the interval in seconds to sleep
                        sleep_in_seconds=TSLEEP*60
                        esp_sleep()
                    else
                        -- Send an error in Sleep command
                        send_status("Sleep command error")
                    
                    end
                else
                    -- Send an error in Sleep command 
                    send_status("Sleep command error")
                end

            else
                -- Command not managed           
                send_status("Command not valid")      

            end
            
        end
        
    end
end

-- Function to turn on the relay
function relay_on()
    
    gpio.write(RPIN,gpio.HIGH)
    send_status("Relay ON")
end

-- Function to turn off the relay
function relay_off()
    
    gpio.write(RPIN,gpio.LOW)
    send_status("Relay OFF")
end

-- Function to check if the the relay is on or off
function relay_status()
    
    risultato=gpio.read(RPIN)

    if(risultato==1) then
        send_status("Relay ON")
    elseif(risultato==0) then
        send_status("Relay OFF")
    end
end


-- Function to send messages to to STOPIC: status topic
function send_status(message)
    mqt:publish(STOPIC, message, MQTTQOS, 0)
    
end

-- Fucntion to send messages to MTOPIC: monitor topic
function send_mstatus(message)
    mqt:publish(MTOPIC, message, MQTTQOS, 0)
    
end


-- Function that sleeps esp8266
function esp_sleep()
 
    send_status("Relay going to sleep now")
    send_mstatus("Relay going to sleep now")
    -- Delayd sleep to send the message above.
    tmr.alarm(3, TGEN*1000, tmr.ALARM_SINGLE, function() 
        node.dsleep(sleep_in_seconds*1000000) 
    end)
end


-- Connection to the mqtt server at the msttport
mqt:connect(MQTTSERVER, MQTTPORT, 0, 1)



-- Send periodically a message to the monitor topic
tmr.alarm(4, TUPDATE*1000, tmr.ALARM_AUTO, function() send_mstatus("Relay Ready") end)

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-- relay.lua

CNAME="relay1" -- Client name

AMBIENT="home" -- Ambient name

STOPIC = AMBIENT.."/"..CNAME.."/status" -- Status topic

CTOPIC = AMBIENT.."/"..CNAME.."/command" --Command topic

MTOPIC = AMBIENT.."/"..CNAME.."/monitor" --Monitor topic

sleep_in_seconds= nil --Sleep in seconds

TUPDATE = 20 -- Time interval for update monitor in seconds

RPIN =1 -- Relay Pin

TGEN = 5 -- Time interval in seconds usend in various trm

gpio.mode(RPIN,gpio.OUTPUT) -- Set Relay pin mode

gpio.write(RPIN,gpio.LOW) -- Default output is OFF

-- Define Client Name and connection parameters

mqt = mqtt.Client(CNAME, 60, "", "", 1)

-- Subscribe to the topics and send status to the status topic

mqt:on("connect", function()

mqt:subscribe(STOPIC, MQTTQOS)

mqt:subscribe(CTOPIC, MQTTQOS)

mqt:subscribe(MTOPIC, MQTTQOS)

send_status("Relay ready again")

end )

-- Callback when mqtt is offline

mqt:on("offline", function() print("mqtt offline"); end)

--Callback to manage messages

mqt:on("message", function(client, topic, data)

manage_message(client, topic, data)

end)

-- Function to filter the messages

function manage_message(client, topic, data)

-- If CTOPIC: command topic

if topic == CTOPIC then

-- If the command is Restart

if data == "Restart" then

send_status("Restarting")

send_mstatus("Restarting")

tmr.alarm(2, TGEN*1000, tmr.ALARM_SINGLE, node.restart)

-- If the command is null

elseif data == nil then

send_status("Command not valid")

-- Command to turn on the Relay

elseif data == "ON" then

relay_on()

-- Command to turn off the Relay

elseif data == "OFF" then

relay_off()

-- Command to check the state of the Relay

elseif data == "Status" then

relay_status()

else

-- Check the Sleep command

i=string.len(data)

dato=string.sub(data,1,5)

if dato == "Sleep" then

ndato=string.sub(data,6)

TSLEEP=tonumber(ndato)

if TSLEEP ~= nil then

if TSLEEP >= 1 then

-- Sets the interval in seconds to sleep

sleep_in_seconds=TSLEEP*60

esp_sleep()

else

-- Send an error in Sleep command

send_status("Sleep command error")

end

else

-- Send an error in Sleep command

send_status("Sleep command error")

end

else

-- Command not managed

send_status("Command not valid")

end

-- Function to turn on the relay

function relay_on()

gpio.write(RPIN,gpio.HIGH)

send_status("Relay ON")

end

-- Function to turn off the relay

function relay_off()

gpio.write(RPIN,gpio.LOW)

send_status("Relay OFF")

end

-- Function to check if the the relay is on or off

function relay_status()

risultato=gpio.read(RPIN)

if(risultato==1) then

send_status("Relay ON")

elseif(risultato==0) then

send_status("Relay OFF")

end

-- Function to send messages to to STOPIC: status topic

function send_status(message)

mqt:publish(STOPIC, message, MQTTQOS, 0)

end

-- Fucntion to send messages to MTOPIC: monitor topic

function send_mstatus(message)

mqt:publish(MTOPIC, message, MQTTQOS, 0)

end

-- Function that sleeps esp8266

function esp_sleep()

send_status("Relay going to sleep now")

send_mstatus("Relay going to sleep now")

-- Delayd sleep to send the message above.

tmr.alarm(3, TGEN*1000, tmr.ALARM_SINGLE, function()

node.dsleep(sleep_in_seconds*1000000)

end)

end

-- Connection to the mqtt server at the msttport

mqt:connect(MQTTSERVER, MQTTPORT, 0, 1)

-- Send periodically a message to the monitor topic

tmr.alarm(4, TUPDATE*1000, tmr.ALARM_AUTO, function() send_mstatus("Relay Ready") end)

The relay.lua file manages the relay, the subscription on MQTT broker with submission of the data. Global parameters have been set to manage the topic, the waiting time in tmr.alarm. There are in particular the following topics

/home/relay1/status : Status topic. The status is sent at the start and at request from the command topic /home/relay1/command.
/home/relay1/monitor: Status of the esp sent periodically to this topic.
/home/relay1/command: Other clients can send commands to the esp:
- Restart: Restarts the esp.
- Sleep n: Put to sleep for n seconds the esp.
- ON: Turn on the relay.
- OFF: Turn off the relay.
- Status: Request of tthe relay status (ON or OFF).

There are various service functions to manage all. The comments in the code describe each feature.

In the next article we will set up the webserver on Beaglebone and the websocket configuration for Mosquitto always on the Beaglebone

MQTT with BeagleBone and ESP8266 – WebServer and MQTT WebSocket

Development, Hardware, Software

MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with temperature sensor

2017-03-23 admin

After loading the firmware into the device esp8266

MQTT with BeagleBone and ESP8266-MQTT ESP8266

we now connect this module with a DHT11 temperature and humidity sensor. Here is how we connect the sensor to the ESP module

In this example we will consider the option of putting the nodemcu in sleep. To have the node back form the sleep the system has to reboot and it is necessary to connect the PIN D0 (GPIO16) to RST PIN as specified in the nodemcu documentation

Nodemcu sleep

Let us take a look at the lua code; It consists of init.lua and tempumid.lua files.

We analyze now the main points of each file

init.lua

-- init.lua
SSID="SSDNAME" -- SSID 
PASSWORD="passwordssid" -- SSID password
TIMEOUT=10000    -- timeout to check the network status
EXSENSOR1="tempumid.lua"    -- module to run
MQTTSERVER="mqttbrokeraddress"   -- mqtt broker address
MQTTPORT="1883"  -- mqtt borker port
MQTTQOS="0" -- qos used

-- Set the netowrk parameters and get ip address
wifi.setmode(wifi.STATION)
wifi.sta.config(SSID, PASSWORD)
wifi.sta.getip()

-- Check the network status after the TIMEOUT interval
tmr.alarm(0, TIMEOUT,tmr.ALARM_SINGLE, function()
    status=wifi.sta.status()
    
    -- if esp8266 got the ip
   if (status == wifi.STA_GOTIP ) then

       dofile(EXSENSOR1)
        
    
    else
        -- Without ip restart the node
        print("Error acquiring ip address=",status)
        node.restart()
    end


end

-- init.lua

SSID="SSDNAME" -- SSID

PASSWORD="passwordssid" -- SSID password

TIMEOUT=10000 -- timeout to check the network status

EXSENSOR1="tempumid.lua" -- module to run

MQTTSERVER="mqttbrokeraddress" -- mqtt broker address

MQTTPORT="1883" -- mqtt borker port

MQTTQOS="0" -- qos used

-- Set the netowrk parameters and get ip address

wifi.setmode(wifi.STATION)

wifi.sta.config(SSID, PASSWORD)

wifi.sta.getip()

-- Check the network status after the TIMEOUT interval

tmr.alarm(0, TIMEOUT,tmr.ALARM_SINGLE, function()

status=wifi.sta.status()

-- if esp8266 got the ip

if (status == wifi.STA_GOTIP ) then

dofile(EXSENSOR1)

else

-- Without ip restart the node

print("Error acquiring ip address=",status)

node.restart()

end

In the file we set the the parameters to access the wifi network, the address and port of the MQTT broker and the file to be run on the ESP after wifi connection to the access point is estabilished. If the ESP does’t acquire the netowrk address the system is restarted.

tempumid.lua

-- tempumid.lua
CNAME="room1" -- Client name 
AMBIENT="home"  -- Ambient name
TTOPIC     = AMBIENT.."/"..CNAME.."/temperature"  -- Temperature topic
HTOPIC     = AMBIENT.."/"..CNAME.."/humidity"  -- Humidity topic 
STOPIC     = AMBIENT.."/"..CNAME.."/status"  -- Status topic
CTOPIC     = AMBIENT.."/"..CNAME.."/command" --Command topic   
MTOPIC     = AMBIENT.."/"..CNAME.."/monitor" --Monitor topic


sleep_in_seconds= nil --Sleep in seconds


TUPDATE = 15 -- Time interval for update monitor in seconds
TUPTEMP = 10 -- Time interval for update temperature and humidity values
SPIN         = 4  -- Sensor pin
TGEN = 5 -- Time interval in seconds usend in various trm


-- Define Client Name and connection parameters
mqt = mqtt.Client(CNAME, 60, "", "", 1) 

-- Subscribe to the topics and send status to the status topic
mqt:on("connect", function() 
    mqt:subscribe(STOPIC, MQTTQOS)
    mqt:subscribe(CTOPIC, MQTTQOS)
    mqt:subscribe(MTOPIC, MQTTQOS)
    mqt:subscribe(TTOPIC, MQTTQOS)
    mqt:subscribe(HTOPIC, MQTTQOS)
    send_status("Sensor ready again")
end )

-- Callback when mqtt is offline
mqt:on("offline", function() print("mqtt offline");  end)

--Callback to manage messages 
mqt:on("message", function(client, topic, data) 
    manage_message(client, topic, data) 
end)


-- Function to filter the messages
function manage_message(client, topic, data) 
    -- If CTOPIC: command topic
    if topic == CTOPIC then
        --print("Command")
        -- If the command is Restart
        if data == "Restart" then
            send_status("Restarting")
            send_mstatus("Restarting")
            tmr.alarm(2, TGEN*1000, tmr.ALARM_SINGLE, node.restart)
            --print("restart")
        -- If the command is null    
        elseif data == nil then
           -- print("Command not valid")
            send_status("Command not valid")
        
        
        else
            -- Check the Sleep command           
            i=string.len(data)
            dato=string.sub(data,1,5)
          
            if dato == "Sleep" then
                ndato=string.sub(data,6)
                TSLEEP=tonumber(ndato)
                if TSLEEP ~= nil then
                    if TSLEEP >= 1 then
                        -- Sets the interval in seconds to sleep
                        sleep_in_seconds=TSLEEP*60
                        esp_sleep()
                    else
                        -- Send an error in Sleep command
                        send_status("Sleep command error")
                    
                    end
                else
                    -- Send an error in Sleep command 
                    send_status("Sleep command error")
                end

            else
                -- Command not managed           
                send_status("Command not valid")      

            end
            
        end
        
    end
end

-- Function to send messages to STOPIC: status topic
function send_status(message)
    mqt:publish(STOPIC, message, MQTTQOS, 0)
    
end

-- Fucntion to send messages to MTOPIC: monitor topic
function send_mstatus(message)
    mqt:publish(MTOPIC, message, MQTTQOS, 0)
    
end

-- Function to display temp and hum
function display_temphum(temp,humi)
    print("Temperature=%d, Humidity=%d",temp,humi)
end

 
-- Function to read and publish temperature and humidity
function read_temp_hum(client)
    status, temp, humi, temp_dec, humi_dec = dht.read(SPIN)
    if status == dht.OK then
    
        mqt:publish(TTOPIC, temp,MQTTQOS, 0)
        mqt:publish(HTOPIC, humi, MQTTQOS, 0)
        
       -- display_temphum(temp,humi)
       
    elseif status == dht.ERROR_CHECKSUM then
        print( "DHT Checksum error." )
    elseif status == dht.ERROR_TIMEOUT then
        print( "DHT timed out." )
    end
end


-- Function that sleeps esp8266
function esp_sleep()
 
    send_status("Sensor going to sleep now")
    send_mstatus("Sensor going to sleep now")
    -- Delayd sleep to send the message above.
    tmr.alarm(3, TGEN*1000, tmr.ALARM_SINGLE, function() 
        node.dsleep(sleep_in_seconds*1000000) 
    end)
end

-- Connection to the mqtt server at the mqttport
mqt:connect(MQTTSERVER, MQTTPORT, 0, 1)

--Sends periodically the temperature and humidity to the topics
tmr.alarm(1, TUPTEMP*1000, tmr.ALARM_AUTO, function() read_temp_hum(mqt) end)

-- Sends periodically a message to the monitor topic
tmr.alarm(4, TUPDATE*1000, tmr.ALARM_AUTO, function() send_mstatus("Sensor Ready") end)

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-- tempumid.lua

CNAME="room1" -- Client name

AMBIENT="home" -- Ambient name

TTOPIC = AMBIENT.."/"..CNAME.."/temperature" -- Temperature topic

HTOPIC = AMBIENT.."/"..CNAME.."/humidity" -- Humidity topic

STOPIC = AMBIENT.."/"..CNAME.."/status" -- Status topic

CTOPIC = AMBIENT.."/"..CNAME.."/command" --Command topic

MTOPIC = AMBIENT.."/"..CNAME.."/monitor" --Monitor topic

sleep_in_seconds= nil --Sleep in seconds

TUPDATE = 15 -- Time interval for update monitor in seconds

TUPTEMP = 10 -- Time interval for update temperature and humidity values

SPIN = 4 -- Sensor pin

TGEN = 5 -- Time interval in seconds usend in various trm

-- Define Client Name and connection parameters

mqt = mqtt.Client(CNAME, 60, "", "", 1)

-- Subscribe to the topics and send status to the status topic

mqt:on("connect", function()

mqt:subscribe(STOPIC, MQTTQOS)

mqt:subscribe(CTOPIC, MQTTQOS)

mqt:subscribe(MTOPIC, MQTTQOS)

mqt:subscribe(TTOPIC, MQTTQOS)

mqt:subscribe(HTOPIC, MQTTQOS)

send_status("Sensor ready again")

end )

-- Callback when mqtt is offline

mqt:on("offline", function() print("mqtt offline"); end)

--Callback to manage messages

mqt:on("message", function(client, topic, data)

manage_message(client, topic, data)

end)

-- Function to filter the messages

function manage_message(client, topic, data)

-- If CTOPIC: command topic

if topic == CTOPIC then

--print("Command")

-- If the command is Restart

if data == "Restart" then

send_status("Restarting")

send_mstatus("Restarting")

tmr.alarm(2, TGEN*1000, tmr.ALARM_SINGLE, node.restart)

--print("restart")

-- If the command is null

elseif data == nil then

-- print("Command not valid")

send_status("Command not valid")

else

-- Check the Sleep command

i=string.len(data)

dato=string.sub(data,1,5)

if dato == "Sleep" then

ndato=string.sub(data,6)

TSLEEP=tonumber(ndato)

if TSLEEP ~= nil then

if TSLEEP >= 1 then

-- Sets the interval in seconds to sleep

sleep_in_seconds=TSLEEP*60

esp_sleep()

else

-- Send an error in Sleep command

send_status("Sleep command error")

end

else

-- Send an error in Sleep command

send_status("Sleep command error")

end

else

-- Command not managed

send_status("Command not valid")

end

-- Function to send messages to STOPIC: status topic

function send_status(message)

mqt:publish(STOPIC, message, MQTTQOS, 0)

end

-- Fucntion to send messages to MTOPIC: monitor topic

function send_mstatus(message)

mqt:publish(MTOPIC, message, MQTTQOS, 0)

end

-- Function to display temp and hum

function display_temphum(temp,humi)

print("Temperature=%d, Humidity=%d",temp,humi)

end

-- Function to read and publish temperature and humidity

function read_temp_hum(client)

status, temp, humi, temp_dec, humi_dec = dht.read(SPIN)

if status == dht.OK then

mqt:publish(TTOPIC, temp,MQTTQOS, 0)

mqt:publish(HTOPIC, humi, MQTTQOS, 0)

-- display_temphum(temp,humi)

elseif status == dht.ERROR_CHECKSUM then

print( "DHT Checksum error." )

elseif status == dht.ERROR_TIMEOUT then

print( "DHT timed out." )

end

-- Function that sleeps esp8266

function esp_sleep()

send_status("Sensor going to sleep now")

send_mstatus("Sensor going to sleep now")

-- Delayd sleep to send the message above.

tmr.alarm(3, TGEN*1000, tmr.ALARM_SINGLE, function()

node.dsleep(sleep_in_seconds*1000000)

end)

end

-- Connection to the mqtt server at the mqttport

mqt:connect(MQTTSERVER, MQTTPORT, 0, 1)

--Sends periodically the temperature and humidity to the topics

tmr.alarm(1, TUPTEMP*1000, tmr.ALARM_AUTO, function() read_temp_hum(mqt) end)

-- Sends periodically a message to the monitor topic

tmr.alarm(4, TUPDATE*1000, tmr.ALARM_AUTO, function() send_mstatus("Sensor Ready") end)

The temumid.lua file manages the measurement of temperature and humidity, the subscription on MQTT broker with submission of the data. Global parameters have been set to manage the topic, the waiting time in tmr.alarm. There are in particular the following topics

/home/room1/temperature: measured temperature topic.
/home/room1/humidity: measured humidity topic.
/home/room1/status : Status topic. The status is sent at the start and at request from the command topic /home/room1/command.
/home/room1/monitor: Status of the esp sent periodically to this topic.
/home/room1/command: Other clients can send commands to the esp:
- Restart: Restarts the esp.
- Sleep n: Put to sleep for n seconds the esp.

There are various service functions to manage all. The comments in the code describe each feature.

In the next article we will set up the esp with the relay

MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with Relay

Hardware

ESP8266 Wifi Module

2016-09-26 admin

In this article we describe briefly the ESP8266 wifi chip from Espressif

ESP8266

This lower power SOC contains a 32 bit RISC MCU and a wifi module. At the Espressif web site we can find the detailed informations about the ESP8266

ESP8266 Resources

The device datasheet is available in the following pdf document

ESP8266 Datasheet

The ESP8266 modules are available individually or in a development platform; the last system simplifies its usage as the development kit contains all the hardware to use rapidly the soc device; we are already ready to load the firmware and use the device.

On internet various web sites describe home automation or iot projects using this soc.

A reference site for the ESP8266 is

ESP8266 Forum

In the forum we can find the various systems utilized to develop applications for the ESP8266. The most relevant tools are

Arduino Ide

Arduino IDE

ESP8266 Arduino github

Espressif SDK

SDK Forum

ESP8266 SDK

PlatformIO

PlatformIO

Nodemcu

Nodemcu at esp8266.com forum

Nodemcu

Nodemcu github

We can buy the ESP8266 module from various internet online websites, for example ebay, as a single module

ESP8266 on ebay

or as a development kit

ESP8266 Development Kit

Different ESP8266 AI-Thinker modules are available

AI-Thinker

We’ll use the Nodemcu development kit. This kit contains the AI-Thinker ESP-12/ESP-12E modules. In the ebay search we have as results ESP8266 ESP-01 modules too and development kits from other vendors.

On the Nodemcu github we can find the development kits we’ll use afterward. There are two versions

Nodemcu V1 (ESP-12E) development kit

Nodemcu devkit V1.0

Nodemcu V0.9 (ESP-12) development kit

Nodemcu devkit V0.9

At the following link we can find the description of the different AI-Thinker modules and as obtain informations about the flash inside the device

ESP8266 Modules

From the Nodemcu github

Nodemcu Devkit

the pins available in the devkit 1.0 are the following

In next articles we’ll describe how to obtain the Nodemcu firmware, how to load it on the device, how to compile it and we’ll show some example using the LUA scripting language utilized by the Nodemcu firmware

Lua

with the LUA software modules available for the ESP8266

Nodemcu documentation

In the next article we’ll describe the Nodemcu firmware

Nodemcu Firmware

Hardware

Beaglebone development board

2016-08-11 admin

In this article we describe briefly the Beaglebone Black development board. What said is applicable also to its derivatives (Green, Enhanced) for most of the information

Beaglebone Black Board

From the above link there is a comparison chart between the various models.

The card is the result of an Open Source project with all its elements distributed on site

Beaglebone Black Design Files

Below are the main features of the BeagleBone Black Rev. C (other versions differ with respect to Black).

CPU	Texas Instruments Sitara AM3358BZCZ100, 1GHz, 2000 MIPS
Graphics Engine	SGX530 3D, 20M Polygons/s
Memory	512 MB DDR3L 800Mhz
On Board Flash	4Gb, 8bit Embedded MMC
Analog Pins	7
Digital Pins	65 (3.3V)
PMIC (Power management integrated circuits)	TPS65217C PMIC and one additional LDO (Low Dropout Regulator)
Debug	20 pin JTAG CT Iopional, Serial Header
Power	Mini USB,DC Jack, 5V DC via Expansion Header
Indicators	1 Power, 2 Ethernet, 4 Led User controllable
USB client Port	Access to USB0, client mode via mini USB
USB Host Port	Access to USB1, socket type A, 500 mA LS/FS/HS
Serial Port	Access UART0 via Header 6 pin 3.3 V TTL
Ethernet	10/100 RJ45
SD/MMC Connector	microSD 3.3 V
User Input	Reset Button, Boot Button, Power Button
Video Output	16b HDMI, 1280x1024 (MAX)
Audio	Via HDMI, Stereo
Supported Interfaces	4x UART, 8x PWM, LCD, GPMC, MMC1, 2x SPI, 2x I2C, A/D Converter, 2xCAN Bus, 4 Timers,2 PRUs
Weight	39.68 grams

From the link

Beaglebone Black Wiki

there is a complete description of all the features and sofware compatibility. The System Reference Document, available as a link in the site mentioned above, can be downloaded from the link

System Reference Beablebone Black

The card being Opensource and with many outputs and built-in controls lends itself very well to prototyping of IOT systems, Automation, Home Automation. The hardware functionality expansion can be executed by the usage of expansion cards called Capes

Beaglebone capes

The main linux distribution for the BeagleBone Black card is Debian. On the Debian distribution for BeagleBone it is also available Cloud9

Cloud 9 Interface

that allows you to interact easily with the hardware on the BeagleBone Black. In subsequent articles we describe the installation, creation of the image and various uses of the card.

Here is the link to the software and hardware features of the card; in particular the page shows the input/outpuy pin of the BeagleBone Black

Beaglebone Black software and hardware

The card can be purchased by following the links listed on the website

Beaglebone Black Purchase

from online retailers or electronics stores.

Hardware

Enigma2 set-top-boxes

2016-07-11 admin

In this article we describe briefly a hardware category using embedded linux in satellite/terrestrial/cable set-top-boxes with the Enigma2 framework.

Enigma2 system is based on Openembedde/Yocto

Openembedded

Wiki Openembedded

and is developed in python; in tv set-top-boxes is present a linux system with its system drivers. This framework was developed and installed in its hardware by Dream Multimedia TV

Dream Multimedia

Dreambox wiki

Dream Multimedia TV distributed source code allowing the creation of alternative system images by various development teams.

Counterfeits of Dream Multimedia set-to-boxes appeared in the market, so they restricted the license and source code distribution, trying to prevent their set-top-boxes cloning.

Other set-top-boxes manufactures developed their version of the open source Enigma2 framework; various developed teams gathered in the OE-Alliance group to develop the common parts of the system, as drivers, a common github, etc, letting to each team their custom personalization. Here is a list of OE-Alliace group development teams and other important teams

OE-Alliance Group

This is the common github link

OE-Alliance github

Using Enigma2 framework it is possible to add other functionalities developing addons, strengthening clearly the set-top-box. HD set-top-boxes use almost exclusively MIPS Broadcom Socs, but with the UHD era manufacturers are beginning to use ARM Broadcom Socs.

Here are some set-top-boxes manufactures that use Enigma2 in their products

Gigablue

Xtrend

Vuplus

In other blogs we’ll decrive how to setup the envinroment and generate an Enigma2 image from source code based on OE-Alliance github or other important team.

Hardware

Orange PI PC board

2016-06-12 admin

In this article we describe an ARM mini pc, similar to Rasperry PI, but cheaper.

Looking at the manufacturer website

http://www.orangepi.org/

we put in evidence the main features of the board:

CPU	H3 Quad-core Cortex-A7 H.265/HEVC 4K
GPU	Mali400MP2 GPU @600MHz·Supports OpenGL ES 2.0
RAM	1GB DDR3 (shared with GPU)
Storage	TF card (Max. 64GB)
Network	10/100M Ethernet RJ45
Audio Input	Microphone
Audio Output	Jack 3.5 mm and HDMI
USB ports	Three USB 2.0 HOST, one USB 2.0 OTG
Low level Periphericals	40 Pins Header,compatibile with layout Raspberry Pi B+
GPIO(1x3) pin	UART, ground
LED	Power Led and Status Led
Key	IR input, POWER

This board belongs to a products family using the same soc, but with different accessories (mmc, ram, network, etc). This model is available for the purchase also from the manufacturer site.

For this device we have various Linux distribution, available from the manufacturer site, but we focus on the following flavours:

Openelec : Media center usage linux distribution.
Armbian: Server/desktop Linux image.

About point 1 informations are available at the following web site:

http://www.orangepi.org/orangepibbsen/forum.php

while from Armbian site we can dowload the Armbian Orange PI image:

http://www.armbian.com/orange-pi-pc/

In next blogs we’ll treat the installation, compilation of these Linux images on Orange PI PC board.

Micro Devices

Category Archives: Hardware

Seeeduino XIAO Board

ESP32 Wifi-Bluetooth Module

Linkit 7688 Duo Connections

Linkit 7688 and 7688 Duo Development Boards

MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with Relay

MQTT with BeagleBone and ESP8266 – MQTT on ESP8266 with temperature sensor

ESP8266 Wifi Module

Beaglebone development board

Enigma2 set-top-boxes

Orange PI PC board

Blog about embedded devices