Hello!
I am trying to integrate Bosch BME280 sensor to my plane (ArduPlane V4.4.0). The script runs for 3 seconds and this happens :
I saw a similar thread, but my code does try to restart itself (shown by exceeded time limit error). If I physically disconnect pixhawk4 and reconnect it again this exceeded time limit error appears again and again. the script runs “properly” for 3 seconds again only if I control+f and reboot pixhawk. maybe something related to memory?
here is my script, adapted from AQmon/lua_modules/bme280.lua at master · avaldebe/AQmon · GitHub
local sensor_addr = 0x76 --the sensor has two address; 0x76 and 0x77
local T,P,H={},{},{} --calib coefficient
local i2c_bus = i2c:get_device(3,sensor_addr) --get device handler, bus 3 = i2ca
function calib()
local c
local function int16_t(uint,nbits) --conversion is needed, see page 24 https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bme280-ds002.pdf
-- first negative number
-- uint8_t (unsigned char ): 2^7
-- uint16_t(unsigned short): 2^15
-- uint32_t(unsigned long ): 2^31
local first_neg=({[8]=0x80,[16]=0x8000})[nbits or 16]
return uint-(uint&first_neg)*2
end
-- Function to convert a table of bytes to a string
local function bytes_to_string(byte_table)
local str = ""
for i = 1, #byte_table do
str = str .. string.char(byte_table[i])
end
return str
end
-- Read data and convert each table to a string
local calib1 = bytes_to_string(i2c_bus:read_registers(0x88, 24))
local calib2 = bytes_to_string(i2c_bus:read_registers(0xA1, 1))
local calib3 = bytes_to_string(i2c_bus:read_registers(0xE1, 7))
-- Concatenate the strings
c = calib1 .. calib2 .. calib3
--little modifications here and there to for lua version 5.3, in particular bit library to normal operators like & and >>
T[1]= c:byte( 1)+c:byte( 2)*256 -- 0x88,0x89; unsigned short
T[2]=int16_t(c:byte( 3)+c:byte( 4)*256) -- 0x8A,0x8B; (signed) short
T[3]=int16_t(c:byte( 5)+c:byte( 6)*256) -- 0x8C,0x8D; (signed) short
P[1]= c:byte( 7)+c:byte( 8)*256 -- 0x8E,0x8F; unsigned short
P[2]=int16_t(c:byte( 9)+c:byte(10)*256) -- 0x90,0x91; (signed) short
P[3]=int16_t(c:byte(11)+c:byte(12)*256) -- 0x92,0x93; (signed) short
P[4]=int16_t(c:byte(13)+c:byte(14)*256) -- 0x94,0x95; (signed) short
P[5]=int16_t(c:byte(15)+c:byte(16)*256) -- 0x96,0x97; (signed) short
P[6]=int16_t(c:byte(17)+c:byte(18)*256) -- 0x98,0x99; (signed) short
P[7]=int16_t(c:byte(19)+c:byte(20)*256) -- 0x9A,0x9B; (signed) short
P[8]=int16_t(c:byte(21)+c:byte(22)*256) -- 0x9C,0x9D; (signed) short
P[9]=int16_t(c:byte(23)+c:byte(24)*256) -- 0x9E,0x9F; (signed) short
H[1]= c:byte(25) -- 0xA1 ; unsigned char
H[2]=int16_t(c:byte(26)+c:byte(27)*256) -- 0xE1,0xE2; (signed) short
H[3]= c:byte(28) -- 0xE3 ; unsigned char
H[4]=(c:byte(30)&0x0F) -- 0xE5[3:0],...
H[4]=int16_t(H[4]+c:byte(29)*16) -- ...,0xE4; (signed) short
H[5]=(c:byte(30)>>4) -- 0xE5[7:4],...
H[5]=int16_t(H[5]+c:byte(31)*16) -- ...,0xE6; (signed) short
H[6]=int16_t(c:byte(32),8) -- 0xE7 ; (signed) char
c=nil
end
calib()
--supplementary function for 5.3 lua, arithmetic shift, shifting the bits and replacing the front bits with zeros
function arshift(value, shift)
-- Check if the value is negative
if value >= 0 then
return value >> shift -- Logical right shift for non-negative values
else
-- For negative values, replicate arithmetic shift
return ((value >> shift) | (0xFFFFFFFF << (32 - shift)))
end
end
function read()
--taking raw measurements
local c = i2c_bus:read_registers(0xF7,8) -- REG_PRESSURE_MSB 0xF7 .. REG_HUMIDITY_LSB 0xFE
local p,t,h -- uncompensated
p=c[1]*4096+c[2]*16+c[3]/16 -- pressure
t=c[4]*4096+c[5]*16+c[6]/16 -- temperature
h=c[7]* 256+c[8] -- humidity
c=nil
local v1,v2,v3,tfine
v1 = t/8 - T[1]*2
v2 = arshift(v1*T[2],11)
v3 = ((v1/2)*(v1/2)>>12)
tfine = v2 + arshift(v3*T[3],14)
t = arshift(tfine*5 + 128,8)
--[[ Pressure: Adapted from bme280_compensate_pressure_int32.
Calculate actual pressure from uncompensated pressure.
Returns the value in Pascal (Pa),
and output value of "96386" equals 96386 Pa = 963.86 hPa. ]]
v1 = tfine - 128000
v2 = (math.floor((v1/8)*(v1/8))>>12)
v3 = (v2*P[3]/8 + v1*P[2]>>20) + 32768
v2 = (v2*P[6] + v1*P[5])/4 + (P[4]<<16)
v1 = (v3*P[1]>>15)
v3 = nil
if v1==0 then -- p/0 will lua-panic
p = nil
else
p = (1048576 - p - (v2>>12))*3125
if p*2>0 then -- avoid overflow (signed) int32
p = p*2/v1
else
p = p/v1*2
end
v1 = (math.floor((p/8)*(p/8))>>13)
v1 = arshift(v1*P[9],12)
v2 = arshift(p*P[8],15)
p = p + arshift(v1 + v2 + P[7],4)
end
--[[ Humidity: Adapted from bme280_compensate_humidity_int32.
Calculte actual humidity from uncompensated humidity.
Returns the value in 0.01 %rH.
An output value of "4132.1" represents 41.321 %rH ]]
v1 = tfine - 76800
v2 = (v1*H[6]>>10)*((v1*H[3]>>11) + 32768)
v1 = (h<<14) - (H[4]<<20) - H[5]*v1
v2 =(v2>>10) + 2097152
v1 = (v1 +16384>>15)*(v2*H[2] + 8192>>14)
v2 = (v1>>15)
v2 = (v2*v2>>7)
v1 = v1 - (v2*H[1]>>4)
-- v1 between 0 and 100*2^22
if v1 < 0 then
h = 0 -- 0 %rH
elseif v1 > 0x19000000 then
h = 10000 -- 100 %rH
else
h = (v1>>12) -- Q22.10, ie 42313 means 42313/1024=41.321 %rH
h = (h*25>>8) -- 0.01 %, ie 4132.1 means 41.321 %rH
end
gcs:send_text(0, "temp result : ".. t)
gcs:send_text(0, "pressure result : ".. p)
gcs:send_text(0, "humidity result : ".. h)
return read(), 1000
end
return read()
Thank you so so much!
