Thingspeak - SmartMon Ext Board P4

This is Part 4 of the SmartMon Extension Board series.

SmartMon v2.7ex Board  is a extension board fully compatible with Arduino, ESP8266, ARM, PIC & other available MCu's out there.  As long as your MCU/Dev Board has I2C Bus capabilities you are good to go!
It is probably one of the easiest ways to create your own Voltage/Current and Power consumption monitoring system for your Projects, devices, batteries, power supplies and many more!


UPDATE !! SmartMon v2.7Ex is available also on Tindie Store !





This time we will go thru a full example on how to monitor your power line and load, read Voltage/Current and Power consumtion data and upload them on the Thingspeak related Channel.

Previous Articles:

• Part 1: General Hardware view, schemastics, etc
• Part 2: RTC Driver example
• Part 3: INA219 Driver and a simple data read example 

What we will need:

• ESP8266 nEXT EVO Board
• SmartMon v2.7Ex Board
• For programming and uploading the driver and the software we will continue to use the LuaUploader as before.  

Software implementation:

Thingspeak channels or standalone Thingspeak Server setup part is not covered in this article.
 If interested to see how can be done a standalone Thingspeak Server, please take a look here:
1. RaspberryPI - Standalone Thingspeak Server install
2. RaspberryPI2 - Thingspeak Server install on Jessie 


To make it running, you need also the function from the previous article:

Part 3: INA219 Driver and a simple data read example 


Send data to Thingspeak function

function sendDataTh()
    print("Sending data to thingspeak.com")
    conn=net.createConnection(net.TCP, 0)
        conn:on("receive", function(conn, payload) print(payload) end)
        -- api.thingspeak.com 184.106.153.149
        conn:connect(80,'184.106.153.149')
        conn:send('GET /update?key=T89U8XLJDPQTW0AR&field1='..volt..'&field2='..current..'&field3='..power..'&field4='..peng..'HTTP/1.1\r\n')
        conn:send('Host: api.thingspeak.com\r\n')
        conn:send('Accept: */*\r\n')
        conn:send('User-Agent: Mozilla/4.0 (compatible; esp8266 Lua; Windows NT 5.1)\r\n')
        conn:send('\r\n')
        conn:on("sent",function(conn) print("Closing connection")
        conn:close()
    end)
    conn:on("disconnection", function(conn) print("Got disconnection...")
    end)
end 

Main Program

---- INA216 Module TEST
init_i2c()
setCAL_reg()
print_values()

If you want to read and update values every minute add function from below:

tmr.alarm( 1, 60000, 1, function()
     print_values()
     sendDataTh()
end)

You can stop your running timer anytime with:

tmr.stop(1)

Smart Mon Ext Board - Software example - P3

This is Part 3 of the SmartMon Extension Board series.

  SmartMon v2.7ex Board  is a extension board fully compatible with Arduino, ESP8266, ARM, PIC & other available MCu's out there.  As long as your MCU/Dev Board has I2C Bus capabilities you are good to go!
It is probably one of the easiest ways to create your own Voltage/Current and Power consumption monitoring system for your Projects, devices, batteries, power supplies and many more!


UPDATE !! SmartMon v2.7Ex is available also on Tindie Store !






Previous Articles:

• Part 1: General Hardware view, schemastics, etc
• Part 2: RTC Driver example

What we will need:

• ESP8266 nEXT EVO Board
• SmartMon v2.7Ex Board
• For programming and uploading the driver and the software we will continue to use the LuaUploader as before.  

Software implementation: 

1.  INIT Data

id = 0
sda = 2
scl = 1
devaddr = 0x40   -- A0,A1 = GND

voltage = 0
current = 0
power = 0
peng = 0
eng = 0

2. I2C  Init function 

function init_i2c()
  i2c.setup(id, sda, scl, i2c.SLOW)
end

3. INA219 Reset function

function reset()
  write_reg(0x00, 0xFFFF)
end

4. Read register function

 --read from reg_addr content of dev_addr
function read_reg_str(reg_addr)
  i2c.start(id)
  i2c.address(id, devaddr, i2c.TRANSMITTER)
  i2c.write(id,reg_addr)
  i2c.stop(id)
  tmr.delay(1)
  i2c.start(id)
  i2c.address(id, devaddr, i2c.RECEIVER)
  c=i2c.read(id, 16) -- read 16bit val
  i2c.stop(id)
  return c
end

5. Read register function - 16bit--returns 16 bit int

function read_reg_int(reg_addr)
  i2c.start(id)
  i2c.address(id, devaddr, i2c.TRANSMITTER)
  i2c.write(id,reg_addr)
  i2c.stop(id)
  tmr.delay(1)
  i2c.start(id)
  i2c.address(id, devaddr, i2c.RECEIVER)
  local c = i2c.read(id, 16) -- read 16bit val
  i2c.stop(id)
  --convert to 16 bit int
  local val = bit.lshift(string.byte(c, 1), 8)
  local val2 = bit.bor(val, string.byte(c, 2))
  return val2
end

6. Write register function

function write_reg(reg_addr, reg_val)
  print("writing reg:" .. reg_addr .. ", reg_val:" .. reg_val)
  i2c.start(id)
  i2c.address(id, devaddr, i2c.TRANSMITTER)
  local bw = i2c.write(id, reg_addr)
  local bw2 = i2c.write(id, bit.rshift(reg_val, 8))
  local bw3 = i2c.write(id, bit.band(reg_val, 0xFF))
  i2c.stop(id)
end

7. Calibration / settings function

function setCAL_reg()
  maxVoltage = 32
  maxCurrentmA = 10000
  write_reg(0x05,3950) --CALIBRATE FOR YOUR rshunt & stuff
  local config = 15391
  write_reg(0x00, config)
end

8. Read Current values (mA)

 function getCurrent_mA()
  local valueInt = read_reg_int(0x04)
  return valueInt
end

9. Read Bus Voltage (V)

 function getBusVoltage_V()
  local valueInt = read_reg_int(0x02)
  -- Shift to the right 3 to drop CNVR and OVF and multiply by LSB = 4
  local val2 = bit.rshift(valueInt, 3)
  local val2 = val2 * 4
  return val2 * 0.001
end

10. Read Shunt resistor voltage drop (mV)

function getShuntVoltage_mV()
  -- Gets the raw shunt voltage (16-bit signed integer, so +-32767)
  local valueInt = read_reg_int(0x01)
  return valueInt * 0.01
end

11. Read Bus Power (W) 

function getBusPowerWatts()
  local valueInt = read_reg_int(0x03)
  return valueInt*20*0.001
end

12. Print read values 

 function print_values()
  volt = getBusVoltage_V()
  print("\nVoltage  :  " .. volt.." V")
  current = getCurrent_mA()/1000
  power = getBusPowerWatts()
  if (current > 65 ) then
         print("ERR 00.23")
         current = 0
         power = 0
  end
  eng = eng + power/60
  print("Current  : " .. string.format("%6.3f",current) .." A")
  print("Power    :  " .. power .." W\n")
  print("Energy   : " .. string.format("%6.3f",eng) .." Wh\n")
end

MAIN Program

---- INA216 Module TEST
init_i2c()
setCAL_reg()
print_values()

If you want to read and update values every minute add function from below:

tmr.alarm( 1, 60000, 1, function()
     print_values()
     sendDataTh()
end)

You can stop your running timer anytime with:

tmr.stop(1)

That's all for today, next time we will more further and we will go thru a full SmartMon Battery Monitor System + Thinkspeak data upload example.
 


All schematics, boards, software and articles released by ESP8266-Projects.com are licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. 

Smart Mon Ext Board - RTC clock driver example - P2

Part 2 of the SmartMon v2.7ex series.


UPDATE !! SmartMon v2.7Ex is available also on Tindie Store !



    This time we are exploring the Real Time Clock  implementation and we will see how easy or complicated is to set & program the onboard RTC Clock.







   And the story behind:

    For a complete monitoring/ data logging experience, a nice to have feature is a proper RTC clock. Having this in mind, for the new version of the SmartMon I choose to add it on-board for a very simple and easy integration in your related Voltage, Current, Power projects.

   The choosen one is the PCF8563 from NXP, a very nice and easy to program CMOS Real-Time Clock (RTC) and Calendar optimized for low power consumption. A programmable clock output, interrupt output and voltage-low detector are also provided. All addresses and data are transferred serially via a two-line bidirectional I2C-bus with a maximum bus speed of 400 kbit/s.


Features: 

     •  Provides year, month, day, weekday, hours, minutes, and seconds based on a

        32.768 kHz quartz crystal
     •  Century flag

     •  Clock operating voltage: 1.0 V to 5.5 V at room temperature

     •  Low backup current; typical 0.25uA at Vdd =3.0V and Tamb=25C

     •   400 kHz two-wire I2C-bus interface (at VDD= 1.8 V to 5.5 V)

     •   Programmable clock output for peripheral devices (32.768 kHz, 1.024 kHz, 32 Hz, and 1Hz)

     •   Alarm and timer functions - separate Alarm triggered MOSFET output with separate voltage   

                     input/supply included onboard, can direct drive upto 2A external devices, 3/5/12V 

                     Relays, interrupts, etc

     •   Integrated oscillator capacitor

     •   Internal Power-On Reset (POR)

     •   I2C-bus slave address: read A3h and write A2h

     •   Open-drain interrupt pin

Schematic:

SmartMon v2.7Ex - RTC module schematic

 For more details about the RTC, please see PCF8563 Datasheet and the related PCF8563 RTC clock driver Article



What we will need:

• ESP8266 nEXT EVO Board
• SmartMon v2.7Ex Board
• For programming and uploading the driver and the software we will continue to use the LuaUploader as before.  

    Connection with the ESP8266 nEXT EVO Board is very easy, as Analog Extension Board - AN1 connector is fully compatible with the nEXTBus connector:

SmartMon v2.7Ex Board

    This time we are talking here about ESP8266/LUA driver but also Arduino implementation will follow.

    If you use another ESP8266, or Arduino, ARM, PIC, whatever MCU you use there days for your projects, then just be sure that you are connecting the I2C lines (SDA/SCL) on the allocated pins for your setup.


Driver implementation

    As PCF8563 has a I2C compatible compatible interface, driver building it following more or less the same  process  as before for I2C devices.

   For more details about the RTC, please take a deeper look at the  PCF8563 Datasheet and the related PCF8563 RTC clock driver Article.



1. Data conversion functions:

  1.1 Decimal to BCD:

        function decToBcd(val)
             local d = string.format("%d",tonumber(val / 10))
             local d1 = tonumber(d*10)
             local d2 = val - d1
            return tonumber(d*16+d2)
         end
  

1.2  BCD to Decimal:

      function bcdToDec(val)
           local hl=bit.rshift(val, 4)
           local hh=bit.band(val,0xf)
          local hr = string.format("%d%d", hl, hh)
          return string.format("%d%d", hl, hh)
     end

 
2. Init I2C bus/interface:

        address = 0x51, -- A2, A1, A0 = 0
        id = 0

        init = function (self, sda, scl)
               self.id = 0
              i2c.setup(self.id, sda, scl, i2c.SLOW)
       end
 

3. ReadTime function:

   readTime = function (self)
       wkd = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" }
       i2c.start(self.id)
       i2c.address(self.id, self.address, i2c.TRANSMITTER)
       i2c.write(self.id, 0x02)
       i2c.stop(self.id)
       i2c.start(self.id)
       i2c.address(self.id, self.address, i2c.RECEIVER)
       c=i2c.read(self.id, 7)
       i2c.stop(self.id)
       return  bcdToDec(bit.band(string.byte(c,1),0x7f)),
               bcdToDec(bit.band(string.byte(c,2),0x7f)),
               bcdToDec(bit.band(string.byte(c,3),0x3f)),
               bcdToDec(bit.band(string.byte(c,4),0x3f)),
               wkd[tonumber(bcdToDec(bit.band(string.byte(c,5),0x7)))],
               bcdToDec(bit.band(string.byte(c,6),0x1f)),
               bcdToDec(string.byte(c,7))
   end


4. SetTime function:

   setTime = function (self, second, minute, hour, day, date, month, year)
       i2c.start(self.id)
       i2c.address(self.id, self.address, i2c.TRANSMITTER)
       i2c.write(self.id, 0x02)
       i2c.write(self.id, decToBcd(second))
       i2c.write(self.id, decToBcd(minute))
       i2c.write(self.id, decToBcd(hour))
       i2c.write(self.id, decToBcd(day))
       i2c.write(self.id, decToBcd(date))
       i2c.write(self.id, decToBcd(month))
       i2c.write(self.id, decToBcd(year))
       i2c.stop(self.id)
   end


For testing,  pack it together and save the code on ESP as 'pcf8563.lua', restart ESP and run:

-- Set Initial Time and Date
require('pcf8563')                                -- call for new created PCF8563 Module Driver
sda, scl = 2, 1                                      --  declare your I2C interface PIN's
pcf8563:init(sda, scl)                           -- initialize I2C Bus
 pcf8563:setTime(0,34,13,12,4,3,15)   -- setTime(s,min,hour,day,weekday,month, year)
-- get Time and Date
require('pcf8563')
sda, scl = 2, 1
pcf8563:init(sda, scl)


s, m, h, d, dt, mn, y = pcf8563:readTime()        --ReadTime function call
=string.format("%s - %s/%s/20%s",dt, d, mn, y)
=string.format(" %s:%s:%s", h, m, s)


Next Article in series can be found here Part 3: INA219 Driver example and software implementation


SmartMon series boards, software and articles by ESP8266-Projects.com are licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. 

Smart Mon Ext Board - Voltage, Current, Power monitor - P1

UPDATE !! UPDATE !!

Available also on Tindie Store !








And the story behind:

Do you remember the BLMS (Battery Live Monitor System) Project?

Today we will start a new Battery Live Monitor System (BLMS) series related with the SmartMon v.2.7Ex Board.

   SmartMonv2.7Ex board has been born as the next generation of BLMS, bringing more flexibility and a lot of extra functionalities than the previous one.

   If you want to quickly add to your project Voltage, Current and Power monitoring capabilities, plus, as a bonus, a proper hardware RTC with integrated Alarm and Timer functions, this is the extension board that you was looking for.

  The modular design will let you to easy connect it and use it with any MCU you want as long as it has I2C bus capabilities  and is working in the 3-5.5V voltage range. That includes all the popular existing platforms like Arduino, PIC, ARM, Atmega, ESP8266 and many more!



Because of the ammount of the information, the related main Videos and Articles are splitted in 4 Parts, as follow:

Part1 - General view
Part2 - Real Time Clock driver example
Part3 - Power Monitor software example
Part4 - Real World example with Thinkspeak data upload



Part 1 - GENERAL VIEW


FEATURES:

• TI INA219 integrated high-side current shunt and power monitor
• High precision, high quality shunt resistor from BOURNS: very low Inductance (10nH) and Temperature Coeficient ( ±20 ppm/°C max.)  
• Measured Bus Current interval: 0-10A (standard) / 0-20A (optional) 

• High range Measured Bus Voltages from 0 to 26 V
• Bus voltage is measured directly on the load side of the shunt resistor
• SmartMon v.2.Ex Power supply voltage range - 3.3 to 5.5V
• Standard I2C bus communication ( nEXT Bus connector)
• PCF8563 RTC - real-time clock and calendar optimized for low power consumption
• RTC Alarm and timer functions with MOSFET driven Interrupt output
• On-board regulator option (can be populated and used it when you want to use the same main BUS Voltage input also as a power supply for the SmartMon Board)

Schematics:

High-side Voltage measurement, current shunt and power monitor

 

RTC

Main Bus Voltage Regulator - optional

PCB: 

SmartMon v2.7Ex - Bottom

SmartMon v2.7Ex - TOP

 Next time in Part2 we will continue exploring the SmartMon v2.7Ex Board and also entering on the software side, talking about the  Real Time Clock usage, Driver example, etc.

P2 - ESP8266 Ultimate DevBoard - Firmware upload and first run

  Part 2 of the the new CBDBv2 Evolution Series


  Let's begin our today story with a quick remember of the CBDBv2 DevBoard features:

• Easy AP/Client Wifi Access
• Easy Firmware Programming
• Easy Software Development (LUA, ESP SDK/Eclipse, Arduino IDE - look at the bottom!)
• 18 bit ADC
• 12 bit DAC
• Voltage Measurement
• Current Measurement
• Temperature Measurement
• Real Time Clock
• High Resolution LCD COG Display with direct sunlight reading 
• User Definable Buttons
• On Board 3.3V Regulator

    Finished Board with headers and some EXT modules in place:

CBDB Evolution - bottom view

EXT Modules

CBDB Evolution - top view

   First thing to see is how easy is the process to configure and start using CBCBv2 (code name Evolution) Board. It will come preconfigured with NodeMCU, so, if LUA is your desired programming language you can just start using it.

   In case of firmware update needed or if you want to change the environment, it is a very easy process, similar with the one used for MPSM Board.


   What we will need:

• CBDBv2 board
• USB adapter (take a look on Part 1 for details how to connect them together)
• NodeMCU firmware (download latest - it's the floating point version for now)
• NodeMCU Flasher ( firmware programmer for NodeMCU DEVKIT) 
• ESPTool ( Bootloader firmware programmer)

Uploading  new firmware:


1. Using the clasic "jumper-style" procedure

• connect CBDB Module with the USB Adapter (Tx, Rx, 3v3, GND), Set the PROG jumper in the Programming mode position (closed) and power on

CBDBv2 - Firmware Programming mode enabled

• Start NodeMCU Flasher. Choose you USB adapter corresponding port
• Add from Config Menu latest previously downloaded firmware. It must start from 0x0000. Disable anything else. 
• Go back on Operation tab. Power off your CBDB Module. Press FLASH Button. power ON quick CBDB module. It will be recognised and will start flashing. Give it a second try if necessary.
•  When finished succesfully A green OK checkmark will appear
•  Power Off CBDB Module, Remove yellow jumper. Power back ON. Your CBDBv2 Board should be now programmed with the new NodeMCU Firmware.

    If you change very often the firmware or want a easier way to use CBDBv2 DevBoard with Arduino IDE or direct GCC/Eclipse programming then maybe you will prefer the second available procedure for uploading your firmware:


2. Using the Auto reset/bootloading mode:

   Another great tool for uploading new firmware for your CBDBv2 DevBoard is esptool.
I want to thank you themadinventor for such a great utility program and also want to thank for the received improvements from several members of the ESP8266 community, including pfalcon, tommie, 0ff and george-hopkins. Great job!

   We will use in this example the CK version (thank you Christian) but any version of esptool that is supporting the RTS/DTR reset/bootloading mode must work ok. If you want to avoid compiling yourself the program you can download the binary file from here:  esptool-bin.zip



    Upload procedure:

• connect CBDB Module with the USB Adapter (Tx, Rx, RTS, DTR, 3v3, GND) and power on

Auto reset/bootloading mode configuration

• In Command Prompt Start esptool.exe program:

         D:\ESPTool>esptool.exe -cp COM34 -cd ck -cf nodemcu_latest.bin

          cp  - Select the serial port device to use for communicating with the ESP.
          cd  - Select the reset method to use for resetting the board.
          cf  - Select the firmware file that you want to flash memory






   For further programming in LUA, it might be possible to do it directly in your Serial Terminal Program but I will recomend you to use a more dedicated program for that, like LuaLoader or LuaUploader. I will stay with the latest one, for it's great flexibility and simplicity.

   To run a quick test, you can just use the code snippets provided by LuaUploader at start-up. Select the piece of code that you want to run and press "Execute Selection" button.

• To quick setup your WIFI network :

        -- One time ESP Setup --
        wifi.setmode(wifi.STATION)
         wifi.sta.config ( "YOUR_WIFI_SSID" , "PASSWORD" ) 
         print(wifi.sta.getip())

• For the Blinky test, just use a prepared LED as in the picture, insert it on previously used yellow jumper place (GPIO0) and run the code from below

Be careful with Anode / catode orientation

                -- Blink using timer alarm --
                timerId = 0 -- we have seven timers! 0..6
                dly = 500 -- milliseconds
                ledPin = 3 -- 3=GPIO0
                gpio.mode(ledPin,gpio.OUTPUT)
               ledState = 0
               tmr.alarm( timerId, dly, 1, function()
                  ledState = 1 - ledState;
                  gpio.write(ledPin, ledState)
               end)






UPDATE !! UPDATE !! UPDATE !!


Yes, it's true.

For all the Arduino IDE lovers:

Arduino IDE first test for direct programming and firmware uploading on the new ESP8266 CBDBv2 Evolution DevBoard. No manual reset needed , no buttons to press, just press Upload and that's it!

 Running Blinky LED program on GPIO15:

// the setup function runs once when you press reset or power the board
void setup() {
     // initialize digital pin 15 as an output.
     pinMode(15, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
     digitalWrite(15, HIGH);   // turn the LED on (HIGH is the voltage level)
     delay(500);              // wait for a second
     digitalWrite(15, LOW);    // turn the LED off by making the voltage LOW
     delay(500);              // wait for a second
}

AT24C32 - I2C External EEPROM Data Looger

      As you remember from our previous article about DS3231 RTC Module, we have identified onboard an EEPROM chip, a 32k AT24C32 one. It is independent from the RTC circuit and conected on the I2C bus, perfect companion for a Data Logger System :)

AT24C32 EEPROM

     The AT24C32 provides 32,768 bits of serial electrically erasable and programmable read only memory (EEPROM) organized as 4096 words of 8 bits each. Might not sound too much but believe it or not you can log 6 months of data or even more on it depending on your application requests and how you organize your data logging. 

    For example if you save your data in 1byte, you will have enough for around 170 days or 24 weeks! With an added 16 extra location available for bulding data header/date/time/CRC/whatever your needs ask for. And if you still feel it to small, you can use anytime AT24C64, 64k size (8192 x 8), direct drop-in replacement!

     Also the device’s cascadable feature allows up to 8 devices to share a common I2C bus. The device is optimized for use in many industrial and commercial applications where low power and low voltage operation are essential. In addition, the entire family is available in 2.7V (2.7V to 5.5V) and 1.8V (1.8V to 5.5V)versions.

 
     FEATURES:

     • Low-Voltage and Standard-Voltage Operation
          –  2.7 (VCC = 2.7V to 5.5V)
          –  1.8 (VCC = 1.8V to 5.5V)
     • Low-Power Devices (ISB = 2μA at 5.5V) Available
      • Internally Organized 4096 x 8
      • 2-Wire Serial Interface
      • Schmitt Trigger, Filtered Inputs for Noise Suppression
      • Bidirectional Data Transfer Protocol
      • 100 kHz (1.8V, 2.5V, 2.7V) and 400 kHz (5V) Clock Rate
      • Write Protect Pin for Hardware Data Protection
      • 32-Byte Page Write Mode (Partial Page Writes Allowed)
     • Self-Timed Write Cycle (10 ms max)
     • High Reliability
          –  Endurance: 1 Million Write Cycles
          –  Data Retention: 100 Years
      • Automotive Grade and Extended Temperature Devices Available
      • 8-Pin JEDEC PDIP, 8-Pin JEDEC SOIC, 8-Pin EIAJ SOIC, and 8-pin TSSOP Packages

   For more details please see AT24C32 Datasheet

  

 What we will need:

• CBDB Board
• USB adapter (take a look on Part 1 for details how to connect them together)
• DS3231 Module from previous article

    For programming and uploading the driver and the software we will continue to use the LuaUploader as before.




Driver implementation

   To be able to access and properly operate with any kind of memory devices we need at least 3 basic functions implemented: addressing, read and write. Plus the proper I2C/SPI/Whaterver bus communication initialisation, ofcourse.

1. Init I2C bus/interface:

        address = 0x50,                         -- A2, A1, A0 = 0
        id = 0

        init = function (self, sda, scl)
               self.id = 0
              i2c.setup(self.id, sda, scl, i2c.SLOW)
       end
 

   ADDRESSING:

   The 32K EEPROM requires an 8-bit device address word following a start condition
to enable the chip for a read or write operation.
It uses the three device address bits A2, A1, A0 to allow as many as eight
devices on the same bus. These bits must compare to their corresponding hardwired
input pins. The A2, A1, and A0 pins use an internal proprietary circuit that biases them
to a logic low condition if the pins are allowed to float.

   The eighth bit of the device address is the read/write operation select bit. A read operation
is initiated if this bit is high and a write operation is initiated if this bit is low.


2. WRITE Function

     A write operation requires two 8-bit data word addresses following the device address word and acknowledgment. Upon receipt of this address, the EEPROM  will again respond with a zero and then clock in the first 8-bit data word. Following receipt of the 8-bit data word, the EEPROM will output a zero and the addressing device, such as a microcontroller, must terminate the write sequence with a stop condition.

   At this time the EEPROM enters an internally-timed write cycle, tWR, to the
nonvolatile memory. All inputs are disabled during this write cycle and the EEPROM will
not respond until the write is complete


   write_EEPROM = function (self, devadr, memadr, edata)
       i = 1
       length = string.len(edata)
       adrh=bit.rshift(memadr, 8)
       adrl=bit.band(memadr,0xff)
       i2c.start(self.id)
       i2c.address(self.id, self.address, i2c.TRANSMITTER)
       i2c.write(self.id, adrh)
       i2c.write(self.id, adrl)
       --print(edata)                               --debug only
       --print(string.byte(edata,1))        --debug only
       while i<=length do
          tmr.wdclr()
          i2c.write(self.id,string.byte(edata,i))
          i = i+1
       end
       i2c.stop(self.id)
   end


3. READ Function

    A random read requires a “dummy” byte write sequence to load in the data word address. Once the device address word and data word address are clocked in and acknowledged by the EEPROM, the microcontroller must generate another start condition.

  The microcontroller now initiates a current address read by sending a device address with the
read/write select bit high. The EEPROM acknowledges the device address and serially clocks
out the data word. The microcontroller does not respond with a zero but does generate a following
stop condition

       read_EEPROM = function (self, devadr, memadr, length)
            adrh=bit.rshift(memadr, 8)
            adrl=bit.band(memadr,0xff)
            i2c.start(self.id)
            i2c.address(self.id, self.address, i2c.TRANSMITTER)
            i2c.write(self.id, adrh)
            i2c.write(self.id, adrl)
            i2c.stop(self.id)
            i2c.start(self.id)
            i2c.address(self.id, self.address, i2c.RECEIVER)
            c=i2c.read(self.id, length)
            i2c.stop(self.id)
           print(c)
           return  c
      end



   For testing,  pack it together and save the code on ESP as 'eeprom.lua', restart ESP and run:

  require('eeprom')                                               -- call for new created AT24C32 Module Driver
  memadr=0x00                                                   -- let's read from begining
  sda, scl = 2, 1                                                    -- I2C pins setup
  edata="4.321 - Data from the EEPROM"        -- Data to write to EEPROM

  eeprom:init(sda,scl)                                   -- Init I2C
  eeprom:write_EEPROM(0x50,0,edata)     -- Write Data edata to EEPROM starting with address=0
  eeprom:read_EEPROM(0x50,0,28)           -- Read Data from EEPROM, address=0, length=28