Monday, August 1, 2016

ESP Basic - I2C Bus scanner example

UPDATE !! UPDATE !!UPDATE !!UPDATE !!
From ESPBasic Version 3.0 Alpha 43 you have also the i2c.setup function available!!

i2c.setup():

Will change the default pins for the i2c interface.  
i2c.setup({SDA}, {SCL})

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From today I will start a new Series related with ESP Basic (www.esp8266basic.com)


When working with a lot of I2C devices one of the first thing that you need is a simple I2C scanner that can help you to identify the IC's and do some very basic troubleshooting.








What we will need: 
  • ESP8266 nEXT EVO Board
  • ESP8266 nEXT EVO - Analog Extension Board - AN1 (I2C devices onboard to test our scanner )
  • For programming and uploading the driver and the software we will use ESP8266 Basic .  


    nEXT EVO + AN-1 extension board



    I2C Scanner Software:

    UPDATE !! UPDATE !!UPDATE !!UPDATE !!
    From ESPBasic Version 3.0 Alpha 43 you have also the i2c.setup function available!!

    i2c.setup():

    Will change the default pins for the i2c interface.  
    i2c.setup({SDA}, {SCL})



              i2c.setup(4,5)
    for address = 1 to 127
       i2c.begin(address)
       stat = i2c.end()

       if stat < 1 then
         ' print stat
          wprint "Found I2C device at address: 0x" & hex(address)
          wprint " - > " & address
          wprint " <br>"
     endif
    next
    wait
     And the scanning result in browser :



    As you can see, has properly detected the I2C devices that are on the AN-1 Extension board:

    - PCF8574      - 8Bit I/O EXT port      - found at address 0x20 -> 32
    -
    LM75           - Temperature sensor    - found at address 0x48 -> 72
    -
    MCP4728    - 4x12Bit DAC              - found at address 0x60 -> 96
    -
    MCP3421    - 18Bit ADC                  - found at address 0x68 -> 10

Please keep in mind that in ESP Basic you have hardcoded I2C pins yet, SDA -> GPIO0 and SCL -> GPIO2.

Don't forget to add if needed pullup resistors on both lines, 4K7 should be OK. In case of AN-1 they are NOT needed.



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