ESP8266 Community Forum

Posted: **Wed Mar 09, 2016 7:39 am**

Hi, Im trying to make a module out of working piece of LUA script, getting error:
SHT21_usage.lua:6: attempt to call field 'Init'

Code: Select all

 local moduleName = ... 
 local M = {}
 _G[moduleName] = M

local pinSDA = 6
local pinSCL = 7
local SHTAddr = 0x40
local id = 0
local eTempHoldCmd        = 0xE3
local eRHumidityHoldCmd   = 0xE5
local eTempNoHoldCmd      = 0xF3
local eRHumidityNoHoldCmd = 0xF5

function M.Init(Ide,SDA,SCL)
  return i2c.setup(Ide, pinSDA, pinSCL, i2c.SLOW)
end

function M.Read_User_Reg(Ide)
  i2c.start(Ide)
  i2c.address(Ide, SHTAddr ,i2c.TRANSMITTER)
  i2c.write(Ide,0xE7)
  i2c.stop(Ide)

  i2c.start(Ide)
  i2c.address(Ide, SHTAddr,i2c.RECEIVER)
  --tmr.delay(1000)
  c=i2c.read(Ide,1)
  i2c.stop(Ide)
  return string.byte(c)
end

function M.Read_Temp(Ide)
  i2c.start(Ide)
  i2c.address(Ide, SHTAddr ,i2c.TRANSMITTER)
  i2c.write(Ide,eTempNoHoldCmd)
  i2c.stop(Ide)
  tmr.delay(100000)

  i2c.start(Ide)
  i2c.address(Ide, SHTAddr,i2c.RECEIVER)
  c=i2c.read(Ide,3)
  i2c.stop(Ide)
  --print("Raw",string.byte(c,1,2))
  d=bit.clear(bit.lshift(string.byte(c,1),8)+string.byte(c,2),1,3)
  return (((d*17572)/65536)-4685)/100;
end

function M.Read_Hum(Ide)
  i2c.start(Ide)
  i2c.address(Ide, SHTAddr ,i2c.TRANSMITTER)
  i2c.write(Ide,eRHumidityNoHoldCmd)
  i2c.stop(Ide)
  tmr.delay(50000)

  i2c.start(Ide)
  i2c.address(Ide, SHTAddr,i2c.RECEIVER)
  c=i2c.read(Ide,3)
  i2c.stop(Ide)
  --print("Raw",string.byte(c,1,2))
  d=bit.clear(bit.lshift(string.byte(c,1),8)+string.byte(c,2),1,3)
  return (((d*12500)/65536)-600)/100
end

--print("Speed ",Init(id,pinSDA, pinSCL))
--print("User reg",Read_User_Reg(id))

--print(string.format("%02.2f",Read_Temp(id)),"deg C")
--print(string.format("%02.2f",Read_Hum(id)),"RH")

return M

and usage:

Code: Select all

SHT21 = require("sht21_2")

pinSDA = 6
pinSCL = 7
id = 0
SHT21.Init(id,pinSDA, pinSCL)

print("Speed ",SHT21.Init(id,pinSDA, pinSCL))
print("User reg",SHT21.Read_User_Reg(id))

print(string.format("%02.2f",SHT21.Read_Temp(id)),"deg C")
print(string.format("%02.2f",SHT21.Read_Hum(id)),"RH")

SHT21 = nil
package.loaded["sht21_2"]=nil

where is the problem? The same structure works for other modules.

Thanks

Posted: **Wed Mar 09, 2016 5:25 pm**

Hey bruh, Fixed the module for j00:

Code: Select all

 local moduleName = ... 
 local M = {}
 _G[moduleName] = M

local SHTAddr = 0x40
local SDA = 5
local SCL = 6
local Ide = 0
local eTempHoldCmd        = 0xE3
local eRHumidityHoldCmd   = 0xE5
local eTempNoHoldCmd      = 0xF3
local eRHumidityNoHoldCmd = 0xF5

function M.Init(Ide,SDA,SCL)
  return i2c.setup(Ide, SDA, SCL, i2c.SLOW)
end

function M.Read_User_Reg(Ide)
  i2c.start(Ide)
  i2c.address(Ide, SHTAddr ,i2c.TRANSMITTER)
  i2c.write(Ide,0xE7)
  i2c.stop(Ide)

  i2c.start(Ide)
  i2c.address(Ide, SHTAddr,i2c.RECEIVER)
  --tmr.delay(1000)
  c=i2c.read(Ide,1)
  i2c.stop(Ide)
  return string.byte(c)
end

function M.Read_Temp(Ide)
  i2c.start(Ide)
  i2c.address(Ide, SHTAddr ,i2c.TRANSMITTER)
  i2c.write(Ide,eTempNoHoldCmd)
  i2c.stop(Ide)
  tmr.delay(100000)

  i2c.start(Ide)
  i2c.address(Ide, SHTAddr,i2c.RECEIVER)
  c=i2c.read(Ide,3)
  i2c.stop(Ide)
  print("Raw",string.byte(c,1,2))
  d=bit.clear(bit.lshift(string.byte(c,1),8)+string.byte(c,2),1,3)
  return (((d*17572)/65536)-4685)/100;
end

function M.Read_Hum(Ide)
  i2c.start(Ide)
  i2c.address(Ide, SHTAddr ,i2c.TRANSMITTER)
  i2c.write(Ide,eRHumidityNoHoldCmd)
  i2c.stop(Ide)
  tmr.delay(50000)

  i2c.start(Ide)
  i2c.address(Ide, SHTAddr,i2c.RECEIVER)
  c=i2c.read(Ide,3)
  i2c.stop(Ide)
  print("Raw",string.byte(c,1,2))
  d=bit.clear(bit.lshift(string.byte(c,1),8)+string.byte(c,2),1,3)
  return (((d*12500)/65536)-600)/100
end

--print("Speed ",Init(id,pinSDA, pinSCL))
--print("User reg",Read_User_Reg(id))

--print(string.format("%02.2f",Read_Temp(id)),"deg C")
--print(string.format("%02.2f",Read_Hum(id)),"RH")

return M

Usage example:

Code: Select all

sht = require("sht21")

sht.Init(0, 5, 6)

temp = sht.Read_Temp(0)
hum = sht.Read_Hum(0)

Posted: **Wed Mar 09, 2016 6:29 pm**

Works like a charm! Thanks. What was the problém? Name of the module needs to be short? Same as file?

Posted: **Fri Mar 11, 2016 6:03 am**

The init had wrong var names:

Code: Select all

function M.Init(Ide,[b]SDA[/b],[b]SCL[/b])
  return i2c.setup(Ide, [b]pinSDA[/b], [b]pinSCL[/b], i2c.SLOW)

Also I assume you saved the module as 'sht21' but you required 'sht21_2'.

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