JN517X Datasheet, PDF (59/100 Pages) NXP Semiconductors – Supports multiple network stacks

NXP Semiconductors
JN517x
IEEE802.15.4 Wireless Microcontroller
When the ADC conversion is complete, an interrupt is generated. Alternatively the
conversion status can be polled. When operating in continuous mode, it is recommended
that the interrupt is used to signal the end of a conversion, since conversion times may
range from 9.5 s to 148 s. Polling over this period would be wasteful of processor
bandwidth.
To facilitate averaging of the ADC value, which is a common practice in microcontrollers, a
dedicated accumulator has been added, the user can define the accumulation to occur
over 2, 4, 8 or 16 samples. The end of conversion interrupt can be modified to occur at the
end of the chosen accumulation period, alternatively polling can still be used. Software
can then be used to apply the appropriate rounding and shifting to generate the average
value, as well as setting up the accumulation function.
For detailed electrical specifications, see Section 14.3.7.
9.16.1.2 Supply monitor
The internal supply monitor allows the voltage on the analog supply pin V_DDA to be
measured. This is achieved with a potential divider that reduces the voltage by a factor of
0.666, allowing it to fall inside the input range of the ADC when set with an input range
twice the internal voltage reference. The resistor chain that performs the voltage reduction
is disabled until the measurement is made to avoid a continuous drain on the supply.
9.16.1.3 Temperature sensor
The on-chip temperature sensor can be used either to provide an absolute measure of the
device temperature or to detect changes in the ambient temperature. In common with
most on-chip temperature sensors, it is not trimmed and so the absolute accuracy
variation is large; the user may wish to calibrate the sensor prior to use. The sensor forces
a constant current through a forward biased diode to provide a voltage output proportional
to the chip die temperature which can then be measured using the ADC. The measured
voltage has a linear relationship to temperature as described in Section 14.3.13.
Because this sensor is on-chip, any measurements taken must account for the thermal
time constants. For example, if the device just came out of sleep or deep sleep mode the
user application should wait until the temperature has stabilized before taking a
measurement.
9.16.1.4 ADC sample buffer mode
In this mode, the ADC operates with a Direct Memory Access (DMA) engine as follows:
• ADC sampling is triggered at a configurable rate using dedicated Timer ADC
• ADC samples are automatically stored in a buffer located in RAM using a DMA
mechanism
• ADC inputs may be multiplexed between different analog sources
The 10-bit ADC data samples are transferred into the buffer in RAM as 16-bit words. The
maximum number of 16-bit words that may allocated in RAM for ADC sample storage is
2047.
The buffer may be configured to automatically wrap around to the start when full.
Interrupts may be configured to indicate when the buffer is half-full, full and has
overflowed.
JN517X
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2.0 — 8 November 2016
© NXP Semiconductors N.V. 2016. All rights reserved.
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