Microchip Technology AVR128DA48 Curiosity Nano Installation guide

AVR® DA Training Manual
Low-Power Modes Using Curiosity Nano
Prerequisites
•Hardware Prerequisites
– AVR128DA48 Curiosity Nano Board (DM164151) with a small hardware modification described in this
document
– Power Debugger (ATPOWERDEBUGGER)
– Two Micro-USB cables: one for the Power Debugger and one for the Curiosity Nano Board
– Two small wires with holes on both ends for pins
•Software Prerequisites
– MPLAB® X 5.40
– MCC plug-in for MPLAB X version 3.95
– AVR library for MCC version 2.3.0
– Atmel Studio newest version
Introduction
This document shows the differences in power consumption between a pure software approach and the use of CIPs
for accomplishing different tasks.
This hands-on training covers the following topics:
• Assignment 1: Event System Compared to Interrupts
• Assignment 2: Software Accumulation Compared to Hardware Accumulation for Analog-to-Digital Converter
(ADC)
Basic theory related to each assignment is introduced at the beginning of each assignment, the functionality is then
verified through the Atmel Studio Data Visualizer.
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Icon Key Identifiers
The following icons are used in this document to identify different assignment sections and to reduce complexity.
Info: Delivers contextual information about a specific topic.
Tip: Highlights useful tips and techniques.
To do: Highlights objectives to be completed.
Result: Highlights the expected result of an assignment step.
WARNING
Indicates important information.
Execute: Highlights actions to be executed out of the target when necessary.
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Table of Contents
Prerequisites.................................................................................................................................................. 1
Introduction.....................................................................................................................................................1
Icon Key Identifiers.........................................................................................................................................2
1. Assignment 1: Event System Compared to Interrupts............................................................................ 4
1.1. Hardware Description...................................................................................................................4
1.2. Modifying the Curiosity Board to Obtain Accurate Power Measurements....................................4
1.3. Explaining the Modules Used.......................................................................................................5
1.4. Creating the Software Implementation Program.......................................................................... 5
1.5. Creating the Event System Implementation Project...................................................................13
1.6. Programming the Device and Comparing Efficiency..................................................................23
2. Assignment 2: Software Accumulation Compared to Hardware Accumulation for ADC.......................28
2.1. Creating the Software Implementation Project...........................................................................28
2.2. Creating the Hardware Implementation Project......................................................................... 34
2.3. Programming the Device and Comparing Power Efficiency.......................................................41
3. Revision History.................................................................................................................................... 46
The Microchip Website.................................................................................................................................47
Product Change Notification Service............................................................................................................47
Customer Support........................................................................................................................................ 47
Microchip Devices Code Protection Feature................................................................................................ 47
Legal Notice................................................................................................................................................. 48
Trademarks.................................................................................................................................................. 48
Quality Management System....................................................................................................................... 49
Worldwide Sales and Service.......................................................................................................................50
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1. Assignment 1: Event System Compared to Interrupts
In this assignment, the power consumption of two different approaches will be compared. The first approach involves
waking up the microcontroller from Sleep through a timer overflow interrupt that starts the ADC conversion to read
the temperature sensor. When the conversion is done, the Result Ready Interrupt is triggered, and the result of the
conversion is read.
In the second approach, the Event System (EVSYS) module will be used. This module allows the user to connect
different peripherals through events. The previous approach will be modified such that the timer overflow will trigger
an event that starts the ADC conversion that reads the temperature sensor. The end of the conversion will wake the
microcontroller from Sleep to read the result.
1.1 Hardware Description
The Curiosity board is based on an AVR128DA48 microcontroller, a Nano embedded debugger, an LED, and a
button. The Nano debugger allows the user to program the board and run debugging features without the need for
external hardware. It also provides UART-USB bridge capabilities.
The Power Debugger is a programmer that also offers power outputs with configurable voltages and can be used to
measure the current consumption of the devices connected to it.
1.2 Modifying the Curiosity Board to Obtain Accurate Power Measurements
To do: Modify the Curiosity Nano board by cutting a trace and soldering two pins.
If the power is observed form the micro-USB port, the Power debugger will consume some power and make the
readings inaccurate.
Figure 1-1. POWER Trace Location
There is a small trace labeled POWER on the Curiosity board. By using a sharp tool, cut the trace until the two holes
are not in contact any more. Check this with a voltmeter.
After the trace has been cut, solder two pins in the holes. To program the board, the two pins have to be connected
with a wire from now on.
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Figure 1-2. Modified Curiosity Board
1.3 Explaining the Modules Used
The modules that will be used in this assignment are the Real-Time Clock (RTC), the ADC, the Voltage Reference
(VREF) and the Event System (EVSYS).
The RTC will work as a timer that counts to one second.
The ADC is a module that transforms an analog voltage into a digital 12-bit number. It can be made to start a
conversion from the EVSYS. It also raises an event and an interrupt when it finishes a conversion. The ADC will be
used to read the internal temperature sensor.
The Voltage Reference is a peripheral that provides stabilized voltages to other peripherals. It also enables the
temperature sensor if it is set to provide 2.048V reference to the ADC.
The Event System is a routing network enabling inter-peripheral communication without involving the CPU. The
communication is done by sending events from one peripherals to another triggering actions. Events are latency-free
and never lost, enabling better real-time and reliable applications.
1.4 Creating the Software Implementation Program
To do: Configure the hardware modules that will be used in this project and add code to the project.
1. Create a new MPLAB X project for AVR128DA48.
1.1. Open MPLAB X.
1.2. Select File → New Project or the New Project button.
Figure 1-3. New Project
1.3. Click Next (the Microchip Embedded Stand-alone Project is selected by default).
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Figure 1-4. Project Type
1.4. In the Device field, search for AVR128DA48. In the Tool category, select the Curiosity Nano board if it
is connected to the computer, otherwise select None. Click Next.
Figure 1-5. Device Selection
1.5. Select XC8 2.20 compiler and click Next.
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Figure 1-6. Compiler Selection
1.6. Give a name to the project (and the location where to be saved) and click Finish.
Figure 1-7. Project Name
2. Open MPLAB Code Configurator (MCC) and configure the peripherals.
2.1. In System Module, choose the clock source as the internal oscillator with 24 MHz clock.
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Info: Choose the Clock source as Internal Oscillator, the Oscillator Frequency Options as
the 24 MHz system clock, and disable the Prescaler.
Figure 1-8. System Module Configuration
2.2. In the Registers tab of System Module, enable Sleep and set the mode to Standby.
Info: Go to the Registers tab in System Module and scroll down to SLPCTRL. Modify the
CTRLA register to enable Sleep and select the mode.
Figure 1-9. Sleep Configuration
2.3. Add the VREF module from Device resources and configure it to provide 2.048V reference to the
ADC.
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Info: The ADC voltage reference must be configured to the internal 2.048V reference. Do
not enable the Force ADC voltage option.
Info: The VREF is used to enable the temperature sensor of the microcontroller.
Figure 1-10. VREF Configuration
2.4. Add the ADC module from device resources and configure it in 12-bit mode, right-adjusted results, no
accumulation, one tick for sample length, and to Run-In Standby (RUNSTBY).
Info: Right-shifted results option must be disabled. The sample length and sample
accumulation number are selected in the Hardware Settings tab. The 12-bit mode is set
by default. The RUNSTBY bit can be changed from the Registers tab and it is found in the
CTRLA register.
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Figure 1-11. ADC Configuration
Figure 1-12. RUNSTBY ADC Configuration
2.5. Add the RTC module from device resources and configure it to use the internal 32.768 kHz oscillator,
have a period of one second, a prescaling factor 1, and Run-In Standby (RUNSTBY) activated.
Info: The clock, prescaling factor, and period are set from the Hardware Settings tab,
while the RUNSTBY bit is found in the register pane in the CTRLA register.
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