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Page 18 of 80
DNT90 Integration Guide - 08/09/12
The DNT90E’s two DAC outputs are labeled DAC0 and DAC1. The DACs can be disabled if unused to
re- duce current consumption. The DAC settings have 12-bit resolution. There are two options for the
DAC full-scale reference:
1.
The DNT90E regulated supply voltage, about 3.3 V
2.
A low impedance voltage source applied to the DNT90E’s ADC_EXT_REF input pin, 2.7 V
maxi- mum. If no connection is made to this pin, a voltage equal to about 2.7 V will be present.
See Section 5.4 for recommendations on configuring the analog I/O, and Sections 7.4.6 and 7.4.7 for de-
tailed information on analog I/O parameters.
3.5 I/O Event Reporting and I/O Binding
The DNT90E’s I/O event reporting function can generate a protocol-formatted
RxEvent
message when
triggered by one of the following I/O events:
- A specific state change of GPIO0, GPIO1, GPIO2 or GPIO3.
- Firing of the periodic event report timer.
- A high or low threshold exceeded on a measurement by ADC0, ADC1 or ADC2.
An I/O report message includes:
- The states of GPIO0 through GPIO5.
- The latest measurements made by ADC0 through ADC2.
- A set of flags indicating which event(s) triggered the I/O report.
- The settings of DAC0 and DAC1.
The I/O binding function works in conjunction with I/O event reporting. When I/O binding is enabled on a
DNT90E, data received in an I/O event report it is mapped as follows:
- GPIO2 will output the state of GPIO0 in the last received event report.
- GPIO3 will output the state of GPIO1 in the last received event report.
- DAC0 will output the voltage read by ADC0 in the last received event report.
- DAC1 will output the voltage read by ADC1 in the last received event report.
I/O binding is used to transmit switch positions or analog signals from one location to another. Note that
I/O binding cannot be used in a DNT90E when SPI slave mode is enabled or differential ADC mode is
used. See Section 5.4 for recommendations on configuring I/O event reporting and binding, and Sections
7.4.6 and 7.4.7 for detailed information on I/O reporting and binding parameters.