Figure 3.2.5
3.3
Digital I/O
The DNT90M’s six digital (state) I/O ports are labeled GPIO0 through GPIO5. GPIO5 has an alternate function of /HOST_
RTS and GPIO4 of /HOST_CTS, providing hardware handshaking for the serial port and SPI slave mode operation. If se-
rial port hardware handshaking is not required and SPI slave mode is not enabled, GPIO4 and GPIO5 can be used for
other digital I/O functions. When SPI slave mode is enabled, GPIO5 and GPIO4
must
be used for /HOST_RTS and
/HOST_CTS respectively, and GPIO3
must
be used to provide the DAV signal (SPI slave mode overrides any other con-
figuration for these ports). Except in SPI slave mode, GPIO0 through GPIO5 are available for customer-defined functions:
- The direction of each GPIO pin can be set for both active and sleep modes.
- The initial state (power on) of all GPIO pins configured as outputs can be set.
- The state of all GPIO pins configured as outputs in sleep mode can be set.
- GPIO triggering of I/O event reporting can be configured.
- GPIO level control of sleep hold-off can be configured.
See Section 5.3 for recommendations on configuring the digital I/O, and Sections 7.4.6 and 7.4.7 for detailed information
on GPIO parameters.
3.4
Analog I/O
The DNT90M’s three ADC input channels are labeled ADC0 through ADC2. The ADC can be disabled if unused to reduce
current consumption. The ADC can be operated in either single-ended mode or differential mode. In single-ended mode,
up to three sensor inputs can be measured. The negative sensor inputs are connected to ground and the positive sensor
inputs are connected to ADC0, ADC1 and ADC2 respectively. Single-ended measurements are unsigned 11-bit values. In
differential mode, one or two sensor inputs can be measured as 12-bit signed values. The first differential measurement is
the difference between the voltage on ADC1 and the voltage on ADC0, and is referred to as the ADC0 differential meas-
urement. The second differential measurement is the difference between ADC2 and ADC0, and is referred to as the
ADC1 differential measurement. Operating the ADC in differential mode takes advantage of common mode rejection to
provide the best measurement stability. Differential mode also incorporates a programmable gain preamplifier function,
with gains settings from 1 to 64 available.
©2012 by Murata Electronics N.A., Inc.
DNT90M Integration Guide (2012/09/17)
Page 14 of 74
www.murata.com
