Murata Electronics North America DNT24 Manuel D’Utilisation
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DNT24 Integration Guide – 03/04/15
3.3 Digital I/O
The DNT24’s six digital (state) I/O ports are labeled GPIO0 through GPIO5. GPIO5 has an alternate func-
tion of /HOST_ RTS and GPIO4 of /HOST_CTS, providing hardware handshaking for the serial port and
SPI slave mode operation. If serial 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 configuration for these ports).
Except in SPI slave mode, GPIO0 through GPIO5 are available for customer-defined functions:
tion of /HOST_ RTS and GPIO4 of /HOST_CTS, providing hardware handshaking for the serial port and
SPI slave mode operation. If serial 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 configuration 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.
- 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.
detailed information on GPIO parameters.
3.4 Analog I/O
The DNT24’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 differ-
ential 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 differ-
ence between the voltage on ADC1 and the voltage on ADC0, and is referred to as the ADC0 differential
measurement. 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 ad-
vantage of common mode rejection to provide the best measurement stability. Differential mode also in-
corporates a programmable gain preamplifier function, with gains settings from 1 to 64 available.
unused to reduce current consumption. The ADC can be operated in either single-ended mode or differ-
ential 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 differ-
ence between the voltage on ADC1 and the voltage on ADC0, and is referred to as the ADC0 differential
measurement. 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 ad-
vantage of common mode rejection to provide the best measurement stability. Differential mode also in-
corporates a programmable gain preamplifier function, with gains settings from 1 to 64 available.
There are two options for the ADC full-scale reference:
1.
The DNT24 regulated supply voltage divided by 1.6, or about 2.06 V
2.
A low impedance voltage source applied to the DNT24’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.
mum. If no connection is made to this pin, a voltage equal to about 2.7 V will be present.
Note that when differential ADC mode is used, the maximum output voltage available from the preamplifi-
er at any gain setting is 2.4 V, so the maximum ADC reading that can be made using a 2.7 V ADC refer-
ence will be about 88.9% of full scale. The ADC channels are read each ADC sample interval, which is
configurable. High and low measurement thresholds can be set for each ADC channel to trigger I/O event
reporting messages.
er at any gain setting is 2.4 V, so the maximum ADC reading that can be made using a 2.7 V ADC refer-
ence will be about 88.9% of full scale. The ADC channels are read each ADC sample interval, which is
configurable. High and low measurement thresholds can be set for each ADC channel to trigger I/O event
reporting messages.
The DNT24’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:
duce current consumption. The DAC settings have 12-bit resolution. There are two options for the DAC
full-scale reference:
1.
The DNT24 regulated supply voltage, about 3.3 V