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ADS1256

Arduino Library for Texas Instrument ADS1256, working with Arduino IDE 1.8.5, Arduino UNO Please read datasheet: http://www.ti.com/lit/ds/symlink/ads1256.pdf

To Do and wish List

  • Add ESP8266/32 support

Branches list

Installation

As any arduino library (download repo, import library)

Compatibility

Tested with arduino UNO and MEGA

Wiring

ADS Board Arduino UNO Board
* 5V 5V
* GND GND
* SCLK pin 13 (SCK)
* DIN pin 11 (MOSI)
* DOUT pin 12 (MISO)
* DRDY pin 9
* CS pin 10
* POWN 5V

Examples

Please refer to the examples and function list below

Basic_Switching_Channel: How to read and change the channels, in single and differential ended mode: https://github.com/adienakhmad/ADS1256/tree/master/examples/ADS1256_Basic_Switching_Channel

ADS1256_Efficient_Input_Cycling: Read and print continuously the ADC values, changes the channel to be read in the next cycle and reads the current ADC data. (reads in differential ended mode): https://github.com/adienakhmad/ADS1256/tree/master/examples/ADS1256_Efficient_Input_Cycling

Basic Functions and methods

  • ADS1256 adc(clockSpeed in Mhz, VREF in volt, boolean if use RESET PIN ): Class Constructor, specify the clockspeed (depends on your board, the reference voltage of the ADC, and if youare conecting the reset pin.

  • adc.waitDRDY(): Data ready Flag, this method waits for the data ready flag (ADC conversion ended and ready to be read). You have to read and wait for this pin signal for the ADC finish the conversion and have a correct timing and Sample Rate. This function is blocking (its a while() until Data ready pin is High), so you should read data "asyncronously" or efficiently (see example code ADS1256_Efficient_Input_Cycling). Returns void

  • adc.isDRDY(): Non blocking function, checks if cycle convertion is completed and data ready to be read. Returns boolean

  • adc.setChannel(x): Sets the channels to be read in next reading cycle, configured in "single end" (reads between the "x" input AINx and ground GND). Returns void

  • adc.setChannel(i,j): Sets the channels to be read in next reading cycle, configured in "differential mode", first argument (i) is the positive input and second argument (j) is negative input to ADC. As stated in device datasheet any combination (i,j) (between 0 and 7) is possible but it's recomended to use adjacent inputs (0 and 1, 2 and 3, etc). Returns void

  • adc.readCurrentChannel(): Returns the value of the currently raw data stored in the MUX register. Returns float (should be changed to long...)

  • adc.readCurrentChannelVolts(): Returns the value of the currently data stored in the MUX register converted to Volts. Returns float

Notice:

According to datasheet, in order to not to lose the previous and new data, it is stored in MUX register and works indepently of the new ADC data channel, every time you change the channel you have to wait for data ready signal for the new channel data to be available to be read.

Take this sequence as Example:

  1. adc.setChannel(2); // will set CH2 to be read in next cycle
  2. adc.waitDRDY(); // will wait until CH2 ADC data is filled in the MUX register
  3. adc.setChannel(3); // will set CH3 to be read in next cycle (data of CH2 will be read next)
  4. adc.readCurrentChannel(); // will read content un the MUX, which is CH2 data
  5. adc.waitDRDY(); // will wait until CH3 ADC data is filled in the MUX register
  6. adc.readCurrentChannel(); // will read content un the MUX, which is CH3 data

This way code and ADC may work faster, as you can do other stuff while ADC reads

Advanced functions

If you want to exploit all the features of the chip (http://www.ti.com/lit/ds/symlink/ads1256.pdf) you can use these functions to read/write the registers

  • adc.sendCommand(command): sends a valid "command" to the ADC. Refer to datasheet http://www.ti.com/lit/ds/symlink/ads1256.pdf for further info, page34. Valid comands:
    • WAKEUP Completes SYNC and Exits Standby Mode
    • RDATA Read Data
    • RDATAC Read Data Continuously
    • SDATAC Stop Read Data Continuously
    • RREG Read from REG rrr
    • WREG Write to REG rrr
    • SELFCAL Offset and Gain Self-Calibration
    • SELFOCAL Offset Self-Calibration
    • SELFGCAL Gain Self-Calibration
    • SYSOCAL System Offset Calibration
    • SYSGCAL System Gain Calibration
    • SYNC Synchronize the A/D Conversion
    • STANDBY Begin Standby Mode
    • RESET Reset to Power-Up Values
    • WAKEUP Completes SYNC and Exits Standby Mode

Example:

adc.sendCommand(SDATAC): Send SDATAC to stop reading contionus data, so we can send other command

adc.sendCommand(RDATAC): Send SDATAC to read contionusly data

  • adc.readRegister(reg): Returns value of the register "reg",

Example:

adc.readRegister(MUX): Read the current content of the MUX register, be aware if the conversion cycle is not complete this will probably read garbage.

ADC Calibration

Refer to the datasheet and advanced functions

Dependencies

This code uses Arduino SPI library and some direct port manipulation

Licence, Atribuions and Contributions

Licence:

Github users:

  • adienakhmad
  • chepo92

Contributions are welcomed to https://github.com/adienakhmad/ADS1256

Notice: Working as 5/1/2019