'----------------------------------------------------------------------------
'!                            HDC2080 READ
'!
'! read temperature and humidity sensor TI HDC2080 and converts into C and %
'! write data into a 24C32 eeprom every minute. Dump eeprom into csv format
'!
'! Aug 2020     Volhout
'----------------------------------------------------------------------------
HDC=&h40      'I2C address of the hdc2080 sensor
NVM=&h57      'I2C address of the EEPROM (CAT24C32)

I2C open 100,100

Dim ar(4)     'ar(0..3) is a copy of hdc2080 registers (0..3)
Dim ad(2)     'ad() is the write pointer in nvm (lsb first)
Dim an(4)     'an() is used for writing pointer (ar(0..1)=0, ar(2..3)=pointer)
Dim av(6)     'av() combines ad() and an() for single I2C send (ad()=swapped)
Dim b         'just a byte variable


start:
 identify
 init_hdc

main:
 Do
   Print
   Input "log(l), clearlog(cl) or dump(d): ";a$
   Select Case a$
     Case "l","L"
       SetTick 60000,do_log
       Print "pres any key to stop logging"
       Do
         a$=Inkey$
       Loop Until a$<>""
       SetTick 0,0
     Case "cl"
       clearlog
     Case "d"
       'dump datapoints in CSV format to terminal
       readpointer
       datapoints = (ad(0)+256*ad(1))/4 - 1
       'set start of data array to adress &h0004
       I2C write nvm,0,2,0,4
       Print "temperature (C),humidity (%)"
       For i=1 To datapoints
         I2C read nvm,0,4,ar()
         convert
         Print Left$(Str$(temperature),5);" , ";Left$(Str$(humidity),5)
       Next i
     Case Else
       End
   End Select
 Loop



' ---------------- timed interrupt sub ---------------

Sub do_log
 startmeasure
 readsensor
 add_log

 'calculate values for information and show
 convert
 'send to terminal
 Print "temperature = ";Left$(Str$(temperature),5);" C  ",
 Print "humidity = ";Left$(Str$(humidity),5);" %"
End Sub



'-----------------------subs sensor-------------------

Sub convert
 temperature = 165*(ar(0)+256*ar(1))/65536 - 40
 humidity = 100*(ar(2)+256*ar(3))/65536
End Sub


Sub identify
 'identify sensor device from register &hfc...&hff
 I2C write hdc,0,1,&hfc
 I2C read hdc,0,4,ar()
 'Print Hex$(ar(0)),Hex$(ar(1)),Hex$(ar(2)),Hex$(ar(3))
 If (ar(0)=&h49 And ar(1)=&h54 And ar(2)=&hd0 And ar(3)=&h07) Then
   Print "hdc2080 found"
 End If
End Sub

Sub init_hdc
 'set measurement configuration in registers &h0e and &h0f
 I2C write hdc,0,1,&h0e
 'register &h0e
 ar(0)=&b00000000    'triggered measure every second
 'register &h0f
 'ar(1)=&b10100000   '9 bit resolution for fast measuremen
 ar(1)=&b01010000    '11 bit resolution for normal measuremen
 'ar(1)=&b00000000   '14 bit resolution for accurate measuremen
 I2C write hdc,0,2,ar()
 trigger=ar(1)+1    'set start bit, auto reset when measurement complete
End Sub


Sub startmeasure
 'for triggered measurements through register 0x0f, write "trigger" to 0x0f
 ar(0)=&h0f
 ar(1)=trigger
 I2C write hdc,0,2,ar()

 'check if measurement finished (read 0x0f and check value bit 0 = 0)
 Do
   I2C write hdc,0,1,ar(0)
   I2C read hdc,0,1,b
   Pause 10
   'Print "wait"
 Loop Until (b = trigger - 1)
End Sub

Sub readsensor
 'read temperature and humidity from registers 0/1 and 2/3
 I2C write hdc,0,1,&h0
 I2C read hdc,0,4,ar()
End Sub


'---------------------- subs nvm ---------------------
Sub writepointer
 'write pointer at NVM address 0 (2 bytes)
 'an() contains nvm adress (2 bytes = 00) and pointer (2 bytes)
 an(0)=0:an(1)=0
 I2C write nvm,0,4,an()
 Pause 20
End Sub

Sub readpointer
 'read pointer at NVM address 0 (2 bytes)
 'set nvm adress to &h0000 (2 bytes)
 I2C write nvm,0,2,0,0
 'read the current data pointer into ad()
 I2C read nvm,0,2,ad()
End Sub

Sub incr_pointer_write
 'increment the data pointer to the next datapair (+ 4 bytes)
 ad(0)=ad(0)+4

 'check if page boundary crossed
 If ad(0)>255 Then
   ad(0)=ad(0)-256
   ad(1)=ad(1)+1
 End If

 'update pointer write array and write
 an(2)=ad(0):an(3)=ad(1)
 writepointer
End Sub

Sub add_log
 'add a temperature an humidity pair to the nvm log
 readpointer

 'move pointer and temp and humidity into 1 array (av()) for sending
 'I2C adresses are MSB first
 av(0)=ad(1):av(1)=ad(0)
 'the data written is a copy of the hdc2080 registers 0,1,2,3
 av(2)=ar(0):av(3)=ar(1):av(4)=ar(2):av(5)=ar(3)

 'send to nvm
 I2C write nvm,0,6,av()
 Pause 20

 'increment data pointer
 incr_pointer_write
 readpointer
 'Print ad(0),ad(1) 'debug: this is the new pointer
End Sub

Sub clearlog
 ad(0)=0:ad(1)=0     'pointer adress to zero + increment = adress 4
 incr_pointer_write
End Sub