2024-09-06 17:21:08 +08:00
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.. zephyr:code-sample:: nrf_battery
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:name: Battery Voltage Measurement
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2020-03-13 21:22:24 +08:00
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2024-09-06 17:21:08 +08:00
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Measure the voltage of the device power supply.
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2020-03-13 21:22:24 +08:00
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Overview
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********
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This sample demonstrates using Nordic configurations of the Zephyr ADC
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infrastructure to measure the voltage of the device power supply. Two
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power supply configurations are supported:
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* If the board devicetree has a ``/vbatt`` node with compatible
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2021-09-23 18:24:19 +08:00
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``voltage-divider`` then the voltage is measured using that divider. An
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example of a devicetree node describing a voltage divider for battery
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monitoring is:
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.. code-block:: devicetree
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/ {
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vbatt {
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compatible = "voltage-divider";
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io-channels = <&adc 4>;
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output-ohms = <180000>;
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full-ohms = <(1500000 + 180000)>;
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power-gpios = <&sx1509b 4 0>;
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};
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};
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* If the board does not have a voltage divider and so no ``/vbatt`` node
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present, the ADC configuration (device and channel) needs to be provided via
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the ``zephyr,user`` node. In this case the power source is assumed to be
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directly connected to the digital voltage signal, and the internal source for
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``Vdd`` is selected. An example of a Devicetree configuration for this case is
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shown below:
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.. code-block :: devicetree
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/ {
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zephyr,user {
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io-channels = <&adc 4>;
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};
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};
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2020-03-13 21:22:24 +08:00
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Note that in many cases where there is no voltage divider the digital
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voltage will be fed from a regulator that provides a fixed voltage
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2021-09-23 18:24:19 +08:00
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regardless of source voltage, rather than by the source directly. In
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2020-03-13 21:22:24 +08:00
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configuration involving a regulator the measured voltage will be
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constant.
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The sample provides discharge curves that map from a measured voltage to
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an estimate of remaining capacity. The correct curve depends on the
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battery source: a standard LiPo cell requires a curve that is different
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from a standard alkaline battery. Curves can be measured, or estimated
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using the data sheet for the battery.
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Application Details
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===================
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The application initializes battery measurement on startup, then loops
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displaying the battery status every five seconds.
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Requirements
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************
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A Nordic-based board, optionally with a voltage divider specified in its
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devicetree configuration as noted above.
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Building and Running
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********************
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2024-09-06 21:41:56 +08:00
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The code can be found in :zephyr_file:`samples/boards/nordic/battery`.
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2020-03-13 21:22:24 +08:00
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.. zephyr-app-commands::
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2024-09-06 21:41:56 +08:00
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:zephyr-app: samples/boards/nordic/battery
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2022-09-15 04:23:15 +08:00
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:board: thingy52/nrf52832
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2020-03-13 21:22:24 +08:00
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:goals: build flash
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:compact:
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Sample Output
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=============
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.. code-block:: console
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*** Booting Zephyr OS build zephyr-v2.2.0-318-g84219bdc1ac2 ***
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[0:00:00.016]: 4078 mV; 10000 pptt
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[0:00:04.999]: 4078 mV; 10000 pptt
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[0:00:09.970]: 4078 mV; 10000 pptt
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[0:00:14.939]: 4069 mV; 10000 pptt
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[0:00:19.910]: 4078 mV; 10000 pptt
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[0:00:24.880]: 4069 mV; 10000 pptt
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