Configuring ADS1115 ADC chip

[Rikki]

Here is some code that has been tested for configuring the ADS1115 ADC chip connected to an 18F13K22 running @ 64Mhz. It is assumed that the address pin on the ADS1115 chip is grounded. Refer to the datasheet for more details on what each of the 16 configuration bits in register #1 are used for.

The datasheet is a bit tricky to decipher but the configuration below works fine

HI2CMode  Master
#define HI2C_BAUD_RATE 125   '
#define HI2C_DATA  PORTB.4  ;18F13K22  family
#define HI2C_CLOCK PORTB.6  ;18F13K22  family

dir HI2C_DATA  in ;data line must be inputs
dir HI2C_CLOCK in ;clock line must be inputs

;ADS1115  ADC setup
;set portc.2 in , to detect ready pulse from ADS1115 (optional)
dir portc.2 in

;ADS1115 i2c address config (assumes the address pin on the ADS1115 is grounded)
#define ADSw 0x90  'i2c address for ADC write
#define ADSr 0x91  'i2c address for ADC read

;configure 16 bit ADC for continuous Read ** NB page 25 of ADS1115 datasheet page 25 figure 31

;NB if a 5v power supply is used the 32768 scale is only partially used and FSR needs to be set to 6.144v in the config register. See datasheet as the ADS1115 can be damaged by overvoltage on the input

;Write to Config register

    do
                    hi2cstart         
                   hi2csend(ADSw)   


  loop while HI2CAckpollState ;wait for ADS1115 to respond

 do

          hi2csend 0x01  ;select config register #1

loop while HI2CAckpollState ;wait for ADS1115 to respond


 do

     hi2csend 0x20  ;MSB of the config register. selects single ended conversion mode, 
                                                ;6.144v FSR, continuous conversion mode

loop while HI2CAckpollState ;wait for ADS1115 to respond

do

  hi2csend 0xE4  ;LSB of the config register, 860 SPS, Ready Pin is active low, 
                                             ;Latch Ready Pin enabled, assert latch after one conversion

loop while HI2CAckpollState ;wait for ADS1115 to respond

 hi2CStop

   ; The next blocked of code enable the conversion-ready function of the ALERT/RDY pin  by setting the Hi_thresh register to 0x8000 and the Lo_thresh register to 0x0000

   ;The chip pulls the 'ready' pin low when a conversion has been completed. The pin goes high after the conversion register is read.

  ;Access & write to Config register 2 Lo_Threshhold register. Write 0x0000 to this register

 do

    hi2cstart         
    hi2csend(ADSw)  

loop while HI2CAckpollState ;wait for ADS1115 to respond

do

      hi2csend 0x02  ;select Lo_thresh register #2

loop while HI2CAckpollState ;wait for ADS1115 to respond

do

   hi2csend 0x00  ;MSB of the Lo_Thresh register

loop while HI2CAckpollState ;wait for ADS1115 to respond

 do

       hi2csend 0x00  ;LSB of the Lo_Thresh register

loop while HI2CAckpollState ;wait for ADS1115 to respond

hi2CStop


 ;Access & write to Config register 3 Hi_Threshhold register. Write 0x8000 to this register to enable conversion ready function

 do
       hi2cstart         
       hi2csend(ADSw)   

loop while HI2CAckpollState ;wait for ADS1115 to respond

 do

      hi2csend 0x03  ;select Hi_thresh register #3

loop while HI2CAckpollState ;wait for ADS1115 to respond


 do

         hi2csend 0x80  ;MSB of the Lo_Thresh register. Set MSB to 1

 loop while HI2CAckpollState ;wait for ADS1115 to respond

 do

          hi2csend 0x00  ;LSB of the Lo_Thresh register

  loop while HI2CAckpollState ;wait for ADS1115 to respond

 hi2CStop

;NB  :now change the Address Pointer register to #0 (conversion register)
;NB : there is no need to repeatedly set the ADS1115 register pointer to 0
;NB : the register pointer will remain locked at 0 until power is cycled 
;NB : or a different register is accessed via coding.
;NB : power on default register index is 0 and the config register #1 needs to be setup ;NB : again after every ADS1115 power off-on cycle

 do
          hi2cstart
          hi2csend(ADSw) 

loop while HI2CAckpollState ;wait for ADS1115 to respond

  do

       hi2csend 0x00  ;point to conversion register

  loop while HI2CAckpollState ;wait for ADS1115 to respond

  hi2cstop

;The ADS1115 chip is now continuously doing ADC conversions and loading the value into register #0, triggering the ready pin when every conversion is completed (1/860 second)

;To read a 16 bit conversion word from the ADS1115 use this code

  do

            hi2cstart
            hi2csend(ADSr)       

loop while HI2CAckpollState ;wait for ADS1115 to respond


            HI2CReceive(gold)  ;ADS1115 response with the MSB of the Conversion register. conversion register already pointed to after config routine

           HI2CReceive(silver) ;ADS1115 response with the LSB of the Conversion register

            HI2CStop

           data = gold * 256 [word] 

           data +=silver

[Anobium]

Rikki. Nice.

Have a look at the attachment. I will add to the demos if you can sort.

The variables are not defined for gold, silver and data. And, data is reserved so I changed to data_value.

I guess gold and silver are some sort of constant?

If you can sort then this would be great to include within the demos

Evan