######################################################################
CCS811_READ:
' Bit 3 = Data Ready 0:no new Data 1:new Data
' Bit 0 Error dedection 0:no Error 1: Error on i2c or Sensor
i2c.writeRegByte CCS811_I2C_ADR, STATUS_REG , 0
i2c.ReqFrom CCS811_I2C_ADR,1
CCS811temp = i2c.read

If CCS811temp and 8 then                               'if Bit3 of status_register =1 then DATA_available
 i2c.writeRegByte CCS811_I2C_ADR, ALG_RESULT_DATA ,0  'selects the Result mailbox
 i2c.ReqFrom CCS811_I2C_ADR, 8
 for i = 1 to 8                                       'The Result mailbox contains  8 Bytes
   BUFFER(i)  = i2c.read
 next
 eCO2 = 256*BUFFER(1) + BUFFER(2)    'eCO2 ppm
 TVOC = 256*BUFFER(3) + BUFFER(4)    'eTVOC
else
 eCO2 = 0
 TVOC = 0
end if

'CCS811 - Keystudio Sensor reading.
'Your sensor address might be diffent
'With help from Annex Wifi RDS forum
' Needs to run for a second to produce results

'Starts

dim as integer RDATA(7)

'Address of various buffers
CC811_ADR =     &h5A
APP_START_REG = &hF4
ALG_Results =   &h02
STATUS_REG =    &h00
MEAS_MOD_REG=   &h01

page write 1

'setup - this needs to happen once.  

i2c open 100,1000
pause 10

'Change from BOOT to APP Mode
i2c write CC811_ADR,0,1,APP_START_REG
pause 10

'Set meaure"  << This needs to be passed ONCE before the sensor will read
i2c write CC811_ADR,0,2,MEAS_MOD_REG,16
pause 10  

''Check the STATUS register (no actual check)
'i2c write CC811_ADR,0,1,STATUS_REG
'pause 10

i2c close

do
 
 i2c open 100,1000
 pause 20
 
 'Set meaure"

 'Check the results "envelope"
 i2c write CC811_ADR,0,1,ALG_Results
 
 pause 20
 
 i2c read CC811_ADR,0,8,RDATA()

 i2c close


'All the data in the resuls register  - uncomment to see
'for x= 0 to 7
'  print rdata(x),
'next x

print

 Print "ECO2 ",(256*RDATA(0))+RDATA(1), "TVOC ",(256*RDATA(2))+RDATA(3)

 page copy 1 to 0,B
 cls
 
 '250ms delay
 pause 250
   
loop