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Arduino serial terminal and tester for AD7745, AD7746 AD7747 with precise i2c communication and automatic offset adjustment

Tested with Arduino IDE 1.8.10 and Arduino AVR Boards Built-In Arduino version 1.8.1 This text is valid for software version V1.5

Serial Terminal Commands:

  • the baud rate is 115200
  • number of digits for a command with parameter must be preserved, excess zeros must not be deleted
  • sent command must be terminated with codes 0x0D + 0x0A ie. CR + LF or \r\n, most PC terminals doing this by default (Arduino Serial Monitor must be set to "Both NL&CR")
  • macros can be created if the PC terminal allows it, but each command must be from the next command separated by codes 0x0D + 0x0A
  • registers 00 - 06 are read only, registers 15 - 18 are factory calibrated and they are not saved to flash memory
  • the sampling period value SamplePeriod (command pwdddd) is a program variable, the minimal sample period is determined by the convert time, set in the CONFIGURATION registry
  • signs in the following text: h = hexadeximal digit, d = decimal digit
  1. FW writes current registers 07-14 to EEPROM memory as default after RESET / POR including CAP Offset register
  2. FR clears the EEPROM memory area in use, registers 07-14 are initialized from PROGMEM after RESET / POR
  3. NN no operation - delay 250 ms
  4. OO automatic offset compensation
  5. OR clear offset compensation (CAPDACs = off, OFFSET = 0x8000 the middle of the interval)
  6. PR prints the sampling period of the converter, in the decimal form dddd, the unit is time in [ms]
  7. PWdddd write setting the AD774X sampling period, dddd are four digits 0000-9999, the unit is time in [ms]
  8. RR prints all registers in the form "R00 = hh R01 = hh… R18 = hh"
  9. RRdd prints one register in the form "Rdd = hh"
  10. RWddhh writes to the register dd hexadecimal value hh, dd are two decimal digits in the range 00 - 18
  11. SS disables / enables periodic sampling of AD774X, default is OFF !!!
  12. TT reads the data registers once and displays them. Makes meaning only when sampling is stop.
  13. VV displays the version of this software
  14. XX restart Arduino with SW reset AD774X including setting its default values

Example:

  • rw10A2<CR+LF> write to configuration register number 10 value 0xA2
  • RW10a2<CR+LF> is identical
  • pw0300<CR+LF> changes the sampling period to 300ms (only until RESET or POR)

Example makro:

  • SS<CR+LF> use it separately for stop sampling
  • RW10A2<CR+LF>NN<CR+LF>TT<CR+LF> and then this as macro - write to configuration register number 10 value 0xA2(start single conversion), set delay 250ms and display recieved data