i2c problems with accelerometer
Posted: Wed Aug 12, 2015 11:01 amHi all
Having some trouble with a sparkfun i2c accelerometer....https://www.sparkfun.com/products/12756
My setup is as follows:
- ESP12 board, good quality 3.3v regulator.
- running standard nodemcu firmware from (http://frightanic.com/nodemcu-custom-build/)
- all other functions (wifi etc) work fine....
When I run an i2c scanner code (lua code), It appears to find the i2c accelerometer as I see
"device found at address 0x1D on IO Index 6 and 7" (this is the way its connected)
The problem is that when I try to get the init() function, I do not get the valid device id back ... always 255
Lua Library:
Test Script:
Having some trouble with a sparkfun i2c accelerometer....https://www.sparkfun.com/products/12756
My setup is as follows:
- ESP12 board, good quality 3.3v regulator.
- running standard nodemcu firmware from (http://frightanic.com/nodemcu-custom-build/)
- all other functions (wifi etc) work fine....
When I run an i2c scanner code (lua code), It appears to find the i2c accelerometer as I see
"device found at address 0x1D on IO Index 6 and 7" (this is the way its connected)
The problem is that when I try to get the init() function, I do not get the valid device id back ... always 255
Lua Library:
Code: Select all
local moduleName = ...
local M = {}
_G[moduleName] = M
-- i2c interface ID
local id = 0
local ADDR = 0x1C --i2c address
-- MMA registers
local MMA_STATUS = 0x00
local MMA_WHOAMI = 0x0D
local MMA_SYSMOD = 0x0B
local MMA_CTRL_R1 = 0x2a
local MMA_CTRL_R2 = 0x2b
-- Wrapping I2C functions to retain original calls
local Wire = {}
function Wire.beginTransmission(ADDR)
i2c.start(id)
i2c.address(id, ADDR, i2c.TRANSMITTER)
end
function Wire.write(commands)
i2c.write(id, commands)
end
function Wire.endTransmission()
i2c.stop(id)
end
function Wire.requestFrom(ADDR, length)
i2c.start(id)
i2c.address(id, ADDR,i2c.RECEIVER)
tmr.delay(20000)
c = i2c.read(id, length)
-- i2c.stop(id)
return string.byte(c)
end
local function readRegister(deviceAddress, address)
Wire.beginTransmission(deviceAddress)
Wire.write(address) -- register to read
Wire.endTransmission()
value = Wire.requestFrom(deviceAddress, 1) -- read a byte
return value
end
local function writeRegister(deviceAddress, address, val)
Wire.beginTransmission(deviceAddress) -- start transmission to device
Wire.write(address) -- send register address
Wire.write(val) -- send value to write
Wire.endTransmission() -- end transmission
end
function setScale()
end
function setODR()
end
function setPL()
end
function setTap()
end
function standby()
local standbyMask = 0x01
retv = readRegister(ADDR,MMA_CTRL_R1)
writeRegister(ADDR,MMA_CTRL_R1,bit.band(retv,bit.bnot(standbyMask)))
end
function active()
local activeMask = 0x01
retv = readRegister(ADDR,MMA_CTRL_R1)
writeRegister(ADDR,MMA_CTRL_R1,bit.bor(retv,activeMask))
end
function M.init(sda, scl)
i2c.setup(id, sda, scl, i2c.SLOW)
retval = readRegister(ADDR,MMA_WHOAMI);
print("WHOAMI:" .. retval)
standby()
setScale()
setODR()
setPL()
setTap()
active()
print("init done, moving to active mode")
end
function M.available()
retval = readRegister(ADDR,MMA_STATUS)
print("available:"..retval)
return retval
end
return M
Test Script:
Code: Select all
SDA_PIN = 6
SCL_PIN = 7
mmaLib = require("mmalib")
mmaLib.init(SDA_PIN, SCL_PIN)
mmaLib.available()
mmaLib = nil
package.loaded["mmalib"]=nil