158 lines
4.9 KiB
Lua
158 lines
4.9 KiB
Lua
--------------------------------------------------------------------------------
|
|
-- BMP085 I2C module for NODEMCU
|
|
-- NODEMCU TEAM
|
|
-- LICENCE: http://opensource.org/licenses/MIT
|
|
-- Christee <Christee@nodemcu.com>
|
|
--------------------------------------------------------------------------------
|
|
local moduleName = ...
|
|
local M = {}
|
|
_G[moduleName] = M
|
|
|
|
--default value for i2c communication
|
|
local id=0
|
|
|
|
--default oversampling setting
|
|
local oss = 0
|
|
|
|
--CO: calibration coefficients table.
|
|
local CO = {}
|
|
|
|
-- read reg for 1 byte
|
|
local function read_reg(dev_addr, reg_addr)
|
|
i2c.start(id)
|
|
i2c.address(id, dev_addr ,i2c.TRANSMITTER)
|
|
i2c.write(id,reg_addr)
|
|
i2c.stop(id)
|
|
i2c.start(id)
|
|
i2c.address(id, dev_addr,i2c.RECEIVER)
|
|
local c=i2c.read(id,1)
|
|
i2c.stop(id)
|
|
return c
|
|
end
|
|
|
|
--write reg for 1 byte
|
|
local function write_reg(dev_addr, reg_addr, reg_val)
|
|
i2c.start(id)
|
|
i2c.address(id, dev_addr, i2c.TRANSMITTER)
|
|
i2c.write(id, reg_addr)
|
|
i2c.write(id, reg_val)
|
|
i2c.stop(id)
|
|
end
|
|
|
|
--get signed or unsigned 16
|
|
--parameters:
|
|
--reg_addr: start address of short
|
|
--signed: if true, return signed16
|
|
local function getShort(reg_addr, signed)
|
|
local tH = string.byte(read_reg(0x77, reg_addr))
|
|
local tL = string.byte(read_reg(0x77, (reg_addr + 1)))
|
|
local temp = tH*256 + tL
|
|
if (temp > 32767) and (signed == true) then
|
|
temp = temp - 65536
|
|
end
|
|
return temp
|
|
end
|
|
|
|
-- initialize i2c
|
|
--parameters:
|
|
--d: sda
|
|
--l: scl
|
|
function M.init(d, l)
|
|
if (d ~= nil) and (l ~= nil) and (d >= 0) and (d <= 11) and (l >= 0) and ( l <= 11) and (d ~= l) then
|
|
sda = d
|
|
scl = l
|
|
else
|
|
print("iic config failed!") return nil
|
|
end
|
|
print("init done")
|
|
i2c.setup(id, sda, scl, i2c.SLOW)
|
|
--get calibration coefficients.
|
|
CO.AC1 = getShort(0xAA, true)
|
|
CO.AC2 = getShort(0xAC, true)
|
|
CO.AC3 = getShort(0xAE, true)
|
|
CO.AC4 = getShort(0xB0)
|
|
CO.AC5 = getShort(0xB2)
|
|
CO.AC6 = getShort(0xB4)
|
|
CO.B1 = getShort(0xB6, true)
|
|
CO.B2 = getShort(0xB8, true)
|
|
CO.MB = getShort(0xBA, true)
|
|
CO.MC = getShort(0xBC, true)
|
|
CO.MD = getShort(0xBE, true)
|
|
end
|
|
|
|
--get temperature from bmp085
|
|
--parameters:
|
|
--num_10x: bool value, if true, return number of 0.1 centi-degree
|
|
-- default value is false, which return a string , eg: 16.7
|
|
function M.getUT(num_10x)
|
|
write_reg(0x77, 0xF4, 0x2E);
|
|
tmr.delay(10000);
|
|
local temp = getShort(0xF6)
|
|
local X1 = (temp - CO.AC6) * CO.AC5 / 32768
|
|
local X2 = CO.MC * 2048/(X1 + CO.MD)
|
|
local r = (X2 + X1 + 8)/16
|
|
if(num_10x == true) then
|
|
return r
|
|
else
|
|
return ((r/10).."."..(r%10))
|
|
end
|
|
end
|
|
|
|
--get raw data of pressure from bmp085
|
|
--parameters:
|
|
--oss: over sampling setting, which is 0,1,2,3. Default value is 0
|
|
function M.getUP_raw(oss)
|
|
local os = 0
|
|
if ((oss == 0) or (oss == 1) or (oss == 2) or (oss == 3)) and (oss ~= nil) then
|
|
os = oss
|
|
end
|
|
local ov = os * 64
|
|
write_reg(0x77, 0xF4, (0x34 + ov));
|
|
tmr.delay(30000);
|
|
--delay 30ms, according to bmp085 document, wait time are:
|
|
-- 4.5ms 7.5ms 13.5ms 25.5ms respectively according to oss 0,1,2,3
|
|
local MSB = string.byte(read_reg(0x77, 0xF6))
|
|
local LSB = string.byte(read_reg(0x77, 0xF7))
|
|
local XLSB = string.byte(read_reg(0x77, 0xF8))
|
|
local up_raw = (MSB*65536 + LSB *256 + XLSB)/2^(8 - os)
|
|
return up_raw
|
|
end
|
|
|
|
--get calibrated data of pressure from bmp085
|
|
--parameters:
|
|
--oss: over sampling setting, which is 0,1,2,3. Default value is 0
|
|
function M.getUP(oss)
|
|
local os = 0
|
|
if ((oss == 0) or (oss == 1) or (oss == 2) or (oss == 3)) and (oss ~= nil) then
|
|
os = oss
|
|
end
|
|
local raw = M.getUP_raw(os)
|
|
local B5 = M.getUT(true) * 16 - 8;
|
|
local B6 = B5 - 4000
|
|
local X1 = CO.B2 * (B6 * B6 /4096)/2048
|
|
local X2 = CO.AC2 * B6 / 2048
|
|
local X3 = X1 + X2
|
|
local B3 = ((CO.AC1*4 + X3)*2^os + 2)/4
|
|
X1 = CO.AC3 * B6 /8192
|
|
X2 = (CO.B1 * (B6 * B6 / 4096))/65536
|
|
X3 = (X1 + X2 + 2)/4
|
|
local B4 = CO.AC4 * (X3 + 32768) / 32768
|
|
local B7 = (raw -B3) * (50000/2^os)
|
|
local p = B7/B4 * 2
|
|
X1 = (p/256)^2
|
|
X1 = (X1 *3038)/65536
|
|
X2 = (-7357 *p)/65536
|
|
p = p +(X1 + X2 + 3791)/16
|
|
return p
|
|
end
|
|
|
|
--get estimated data of altitude from bmp085
|
|
--parameters:
|
|
--oss: over sampling setting, which is 0,1,2,3. Default value is 0
|
|
function M.getAL(oss)
|
|
--Altitudi can be calculated by pressure refer to sea level pressure, which is 101325
|
|
--pressure changes 100pa corresponds to 8.43m at sea level
|
|
return (M.getUP(oss) - 101325)*843/10000
|
|
end
|
|
|
|
return M |