EVAL-AD7719-EB Datasheet, PDF (12/21 Pages) Analog Devices – Evaluation Board for the AD7719, 16&24-Bit, Dual Sigma Delta ADC

EVAL-AD7719-EB
Fig. 9. The I/O and Current Source Control RegisterScreen
The I/O and Current Source Control Register Screen
Fig.9. shows the I/O and Current Source Control Register Screen. This screen allows the user to control the on-chip
200uA current sources and also the two I/O ports P3 & P4 and the output ports P1 & P2. When the screen is loaded,
the software reads the current contents of the I/O and Current Source Control Register of the AD7719 and sets the
buttons accordingly. The current sources IEXC1 & IEXC2 can be enabled and directed to the two AD7719 output pins
IOUT1 & IOUT2 by the user. The on-chip burnout current can be turned on/off by the user.
The two I/0 ports P3 & P4 can be selected as inputs or outputs, the user can set the outputs as required - note 'high'
represents a 5V output on the pin, 'low' represents AGND. The user can also read in the value at the inputs P3 & P4 if
configured as inputs. Note pressing Update Display button will read the current contents of the I/O and Current Source
Control Register and update the screen.
The two outputs P1 & P2 can be configured as a standard Output pin or as a Power Switch to PWRGND. When selected
as an Output pin P1 or P2 can be enabled as a regular digital output or as a tri-state output. Everytime a change is made,
the software writes the new conditions to the AD7719 and then reads back from the I/O and Current Source Control
Register for conformation - ignoring databits P1DAT - P4DAT. Refer to AD7719 datasheets for more information.
The Mode Register Screen
The Mode Register Screen is shown in Fig. 10. When the screen is loaded the software reads the current contents from
the Mode Register of the AD7719 and sets the buttons accordingly. This screen allows the user to change the operating
mode of the AD7719, change the channel configuration and power down the crystal oscillator. When the user selects
a calibration the software will start a calibration by writing to the AD7719 (prompt user for input if system calibration)
and then monitor the RDY pin. A falling edge of the RDY pin will indicate that the calibration has been completed. After
a calibration the AD7719 is placed in the idle mode and the screen is updated to indicate this. Everytime a change is
made, the software writes the new conditions to the AD7719 and then reads back from the Mode Register for
conformation. The AD7719 should be powered-down or placed in Idle Mode before writing to Filter, ADC Control or
Calibration registers. The default status for the Mode register is 0 hex - refer to AD7719 datasheets for more information.
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Rev. B