"As we all know, at present, battery has become the fatal weakness of mobile devices. With the continuous warming of IOT, power consumption also poses a severe challenge to the budding Internet of things applications. Not long ago, aiban.com released the ATMEL Sam L21 xplained Pro development board activity. Its ultra-low power consumption directly points to the low power consumption limit of 32-bit ARM microcontroller, which is impressive. Today, let's thoroughly understand the SAM L21 development board and see what its features are? How to achieve such low power consumption?
SAM L21 Xplained Pro
At first glance, the SAM L21 xplained Pro is not much different from ATMEL xplained Pro Series boards we usually contact in terms of packaging or board itself. Perhaps the most eye-catching is the naming of Sam L21, which represents ultra-low power consumption.
The most convenient part of xplained Pro Series development board is that it provides ATMEL standard 20pin expansion interface, which can be compatible with other xplained Pro expansion boards, so as to facilitate engineers to evaluate and develop ATMEL microcontroller. After carefully looking at the SAM L21 development board in the hands of the writer, the most interesting ones are the SAM L21 (SAM L21 Data Book) microcontroller on the front of the board and the XAM module on the back of the board. L21 needless to say, is the focus of this evaluation. What is the XAM module? ATMEL has never appeared on the previous xplained Pro board. What role does it play? Let's start with the resources on the whole board to uncover the functions of these devices.
ATMEL Sam L21 xplained Pro is a 4-layer PCB board with a size of 100mm * 60MM. The main resources on board are:
Atsaml21j18a (atsaml21j18a Data Book) microcontroller
One mechanical reset button, one mechanical user button
Spare battery
32.768KHz crystal oscillator
USB interface, device and host mode
Three 20pin xplained Pro extension interfaces
A qtouch button
XAM module
Edbg embedded debugging module, data gateway interface: SPI, I ² C. 4 GPIO, virtual COM ports (CDC)
One yellow status LED, one yellow user led, one green power LED
USB power supply
Support application examples with ATMEL software framework (ASF)
From the perspective of the resources on the board, the two main attractions are the on-board master Sam L21 and the XAM module on the back. What are the specific functional features? Let's split it up（ (next page)
ATMEL development board recommendations:
Atsam3s Evaluation Kit A Cortex-M3 flash microcontroller with high integration and low power consumption.
Atsam4c Evaluation Kit A 32-bit arm ® Cortex ®- Evaluation Kit for M4 sam4c microcontroller.
Atsama5d31 Evaluation Kit An evaluation platform that allows users to widely evaluate, prototype and create application specific designs.
Atsam4e-xpro Evaluation Kit A microcontroller that evaluates atsam4e16e and supports studio integrated development platform.
Atsaml21j18a microcontroller
The microcontroller model of ATMEL Sam L21 xplained Pro is atsaml21j18a. It is the MCU with the highest specification and configuration in Sam L21 series. It is based on arm Cortex-M0 + processor and 48mhz main frequency. It is packaged in lqfp64 commonly used by microcontrollers, as shown in the figure below.
(click the picture to enlarge)
Atsaml21j18a features:
Based on arm Cortex-M0 + processor, 48mhz main frequency, internal integration of 256Kb flash and 40KB SRAM
The working power consumption is 35ua / MHz, and the sleep power consumption is 200na / MHz
Six serial communication modules (sercom), configurable as UART / USART, SPI or I2C
8 16 bit timing / counters, 32-bit real-time clock and calendar, 24 channel PWM
A 20 channel 12 bit ADC, 2-channel 12 bit DAC and three operational amplifiers
Full speed USB, supporting slave and host device modes
Touch interface supporting up to 192 channels
Supply voltage of 1.62V ~ 3.63v
Pin compatible with Sam D20 and samd21 series Microcontrollers
Support ATMEL studio IDE, ASF and Sam L21 xplained Pro Toolkit
For more detailed features of atsaml21j18a microcontroller, please refer to the datasheet on ATMEL's official website. However, I believe that engineers are most interested in the low power consumption of Sam L21 microcontroller. In fact, in addition to the low power consumption of Sam L21 itself, there is also a power consumption domain within Sam L21, which contains the power consumption profile corresponding to each part or function of MCU, which is also one of the key factors of Sam L21's low power consumption. Under normal circumstances, MCU uses these configuration files to completely close the unnecessary parts and functions of MCU and only turn on the necessary functions. In addition, when the necessary functions are started, the hardware power consumption responsible for these functions can also be regulated to minimize, as shown in the system block diagram below.
As can be seen from the above figure, Sam L21 contains five power consumption domains: pd0, PD1, PD2, pdtop and pdbackup.
Pd0 belongs to the lowest power consumption domain, which includes event system, general clock control, crystal oscillator control, master clock control, etc. in addition, pd0 also includes a series of peripheral controls, which allows the device to wake up through external interrupts.
PD1 belongs to the medium power domain, which includes DMA controller, peripheral access controller, low-power bus matrix, etc.
PD2 is the highest power consumption domain, including Cortex-M0 +, storage, SRAM, USB, etc.
Pdtop includes watchdog timer, external interrupt, etc.
Pdbackup includes 32kHz clock, reset control, RTC control, etc.
The relationship between these power consumption domains is also very simple, which means that a large circle wraps a small circle. Once PD2 is activated, pd0, PD1, pdtop and pdback must be activated; If PD1 is activated, then (pd0, pdtop, pdback) must be activated; If pd0 is activated, pdtop (pdback) must be activated; If pdtop is activated, pdbackup must be activated; Unless in the off sleep mode (the initial section of the whole device is powered off), pdbackup is always activated. From such a detailed division of power domain, it is reasonable that ATMEL can control the power consumption of Sam L21 so well.
XAM module
On the SAM L21 board, another interesting thing is the XAM module on the back of the board. The full name of XAM is xplained Pro analog module. It is also the first time to "come out" on Sam L21 board. It enables engineers to measure the current (power consumption) of the board through the original edbg module interface. What's the specific matter? Look at the picture below.
Take a closer look, stunned, are there trees? This is the microcontroller of ATMEL's Sam D series (D21 development board evaluation article). The brief hardware system block diagram of the whole XAM module is as follows:
The XAM module contains: (next page)
A calibration circuit
A reference voltage
Analog front end
Microcontroller (SAM D20)
ATMEL development board recommendations:
Atsam3s Evaluation Kit A Cortex-M3 flash microcontroller with high integration and low power consumption.
Atsam4c Evaluation Kit A 32-bit arm ® Cortex ®- Evaluation Kit for M4 sam4c microcontroller.
Atsama5d31 Evaluation Kit An evaluation platform that allows users to widely evaluate, prototype and create application specific designs.
Atsam4e-xpro Evaluation Kit A microcontroller that evaluates atsam4e16e and supports studio integrated development platform.
The XAM module has four current measurement ranges, which are controlled by two shunt resistors and two gain levels of the analog front end. The specific measurement resolutions are shown in the table below, which are 20na, 150nA, 10uA and 100ua. The XAM will automatically switch the measurement range to achieve the optimal measurement results.
Accordingly, on ATMEL Sam L21 xplained Pro card, whether to enable XAM module is controlled by adding the compatible design of jumping cap in the circuit. As shown in the figure below, whether to "build" its own circuit according to the actual demand can be "built". Is the power supply of MCU and peripheral equipment through XAM module? Or get the power directly through the voltage reducer.
Use of Sam L21 xplained Pro development board
After understanding several important features of Sam L21 xplained Pro development board, let's take a look again. First, you can install two development and debugging software for auxiliary development, ATMEL studio 6.2 and ATMEL data visualizer 2.1.
Data Visualizer
We believe that ATMEL studio is familiar to everyone, and data visualizer is a program of ATMEL for processing and visualizing data, including power consumption measurement, oscilloscope, data acquisition and other functions. It can be used to receive data from various sources, such as ATMEL's edbg module interface, COM port and software, which can be officially downloaded in ATMEL, as shown in the figure below.
Open the data visualizer and power on ATMEL Sam L21 xplained pro. We can see that the software can directly identify ATMEL's development board.
Select the corresponding COM port and click Connect. You can see the data printed by the serial port when the board runs the factory program from the data visualizer（ (next page)
Let's take another look at the power consumption measurement function of data visualizer, as shown in the figure below. Select the power function, and let's take a look at the power consumption of the SAM L21 board's default factory program. The following are the power consumption measurements when the board does not do any operation and the LED is lit.
For more power consumption tests of Sam L21 and the use of data visualizer software, you can refer to the following experience:
Low power test of Sam L21
How to use the data visualizer to view the running power consumption of L21
Atmel Studio6.2
In addition to the built-in factory programs, we can also download other programs through ATMEL studio 6.2. There are many Sam L21 routines officially provided by ATMEL. At first glance, there are more than 100. Select a routine named FreeRTOS demo using oled1 xplained Pro Sam L21 xplained pro (which needs to be implemented in conjunction with ATMEL's oled1 xplained Pro extension board) to compile and download.
After downloading, reset the board, and we can see the pseudo-random signal on the OLED screen, as shown in the figure below.
At this time, different displays can be switched through the mechanical keys on the OLED expansion board. For example, by pressing the middle mechanical key, we can input information from the serial port tool to the OLED screen, as shown in the figure below. Enter "www.eeboard. Com", and the corresponding information will be displayed on the screen.
More routines will not be demonstrated one by one in this evaluation. Those interested in experiencing Sam L21 board can contact aiban.com to apply for trial.
Summary
This paper introduces ATMEL's latest ultra-low power development board Sam L21 xplained pro. The board is equipped with low-power microcontroller atsaml21j18a based on arm Cortex-M0 +, current test module XAM based on Sam D series microcontroller and other resources. Combined with ATMEL xplained Pro series expansion board, it is convenient for engineers to effectively evaluate the performance and functions of onboard microcontroller, Today, with the continuous growth of Internet of things products, the problem of power consumption deserves more and more attention. The low-power microcontroller Sam L21 launched by ATMEL moistens people's hearts just like the dew of a long drought. It can be regarded as the perfect control solution for low-power IOT. Exciting friends can contact Aiban to apply for trial.
reference material
Sam L21 xplained Pro development board materials
Let as6 find the SAM L21 development board
Sam L21 xplained Pro introduction
Simplify embedded system design -- evaluation of xplained Pro development board equipped with ATMEL Sam D21
End explosion of coprocessor in iphone5s – initial experience of ATMEL samg53-xpro development board
The richest communication interface -- atsam4e-xpro development board evaluation
"The same root as Arduino" -- ATMEL atmega328p-xmini development board evaluation
One of the best 8 / 16 bit microcontrollers -- ATMEL xmega-b1 xplained development board evaluation
Completely free DIY Mini evaluation board -- Atmega168 xplained Mini evaluation
Theme of ATMEL xplained Pro platform
ATMEL development board recommendations:
Atsam3s Evaluation Kit A Cortex-M3 flash microcontroller with high integration and low power consumption.
Atsam4c Evaluation Kit A 32-bit arm ® Cortex ®- Evaluation Kit for M4 sam4c microcontroller.
Atsama5d31 Evaluation Kit An evaluation platform that allows users to widely evaluate, prototype and create application specific designs.
Atsam4e-xpro Evaluation Kit A microcontroller that evaluates atsam4e16e and supports studio integrated development platform.
Original statement: This article is original by Aiban. Reprint is declined“
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