Raspberry Pi 3 Model A+ - Review

Table of contents

RoadTest: Raspberry Pi 3 Model A+

Author: ljakes

Creation date:

Evaluation Type: Development Boards & Tools

Did you receive all parts the manufacturer stated would be included in the package?: True

What other parts do you consider comparable to this product?: Raspberry Pi 1 Model A+ Raspberry Pi 3 Model B+

What were the biggest problems encountered?: none

Detailed Review:

Introduction:

Thanks to Element 14 for the opportunity to thoroughly test this product to the best of my capability with the support test equipment and test aids that I have at hand.  For this roadtest I will be testing the performance the Raspberry Pi 3 Model A+ (delivered item), the latest Raspberry Pi 3 B+ and the original Raspberry Pi 1 Model A+ that I had on hand and compare the results, emphasizing the differences relating to performance and features.

 

 

The Technical differences are:

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Hardware /Software:

 

This is the product I received (Raspberry PI 3 Model A+) visually compared to the original Raspberry Pi 1 Model A+ which I had on hand:

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Raspberry PI 3 Model A+ (on left) and Original Raspberry PI 1 Model A+ (on right) front and back.

 

The footprint is exactly the same. The RPi3 A+ weighs 0.2 ounces more than the RPi1 A+.  The addition of the 2.4/5 GHz WLAN circuitry is visible in the lower left corner of the Pi3 A+ board.  As you can see, the new CPU includes a metal heatspreader that helps keep cpu temps down.  On the back of the board the added ELPIDA 512 MB RAM Module is visible.

 

 

No software was provided.

 

 

These are the other items used that I had on hand:

 

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Raspberry PI 3 Model B+.

 

As you can see, the Pi3 Model B+ contains all the same circuitry as the Pi3 A+ but has a bigger footprint because it has the following additional hardware:

     10/100/100 Ethernet LAN with 100M and LNK LEDs.

     3 additional USB 2.0 connectors.

     PoE 4-pin Header for Power over Ethernet adaptation.

 

 

 

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2.4 GHz Wifi Dongle.

 

 

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Logitech K400r keyboard.

 

 

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5 volt 3 Amp ac to dc power adapter.

 

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Sandisk U3 32GB µSD Memory Card.

 

 

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P4460 Kill A Watt Power Meter.

 

 

Discussion:

 

As you can see from the pictures and comparison table above, there are many electrical and physical differences among these three devices.  However, they all serve the same basic function as a Single Board Computer (SBC).

 

 

I will concentrate on testing the performance of the CPU, RAM throughput, Ethernet throughput, power consumption and CPU temperature.

 

The first steps are to load the following latest standard software on the Raspberry Pi's in the following sequence:

 

    1.  Raspbian Stretch Lite OS dated 14 May 2019, Kernel Version 4.19.42-v7+.

 

    2.  Run update and upgrade to make sure that the latest Linux drivers are in place.

 

    3.  Setup static IP so that I can SSH into the Raspberry Pi from my desktop and disconnect the monitor and keyboard from the Raspberry Pi and also know exactly where the Raspberry Pi is     located(IP) on my home network at all times.

 

    4.  Install samba software so I can easily transfer data to my desktop for analysis using Microsoft Excel and inclusion into this report.

 

    5.  Install sysbench 0.4.12 to perform benchmark cpu and memory tests.

 

    6.  The resultant software on the microSD will run on all three Raspberry Pi's.

 

 

TESTS:

 

1. CPU Performance:

 

The following results were obtained using sysbench running primes generator on all three Raspberry Pi's set at 1 thread or core:

 

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    RPi3 Model A+ CPU running 1 core                                           RPi3 Model B+ CPU running 1 core                                         RPi1 Model A+ CPU running 1 core

 

With 1 core exercised the RPi1 Model A+ performed significantly slower than both the RPi3 Models A+ and B+.  As expected the RPI3 Models A+ and B+ performed exactly the same at 31.6 events per second while the RPi1 Model A+ ran at 10.2 events per second which was 208.9 percent slower.  The biggest reason for this is the fact that the RPi1 Model A+ CPU is only running at 700 MHz whereas the RPi3 CPU is running at 1400 MHz.

 

 

The following results were obtained using sysbench running primes generator on the two Raspberry Pi3's set at 4 threads or cores:

 

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    RPi3 Model A+ CPU running 4 cores                                                 RPi3 Model B+ CPU running 4 cores

 

As expected, with all 4 cores exercised the RPi3 Models A+ and B+ perform the same at 125 events per second.

 

 

 

2. Memory Performance:

 

 

The following results were obtained using sysbench running speed tests read mode on all three Raspberry Pi's set at 1 thread or core:

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   RPi3 Model A+ Memory Read running 1 core                RPi3 Model B+ Memory Read running 1 core                RPi1 Model A+ Memory Read running 1 core

 

With 1 core exercised the RPi1 Model A+ performed with significantly less throughput than both the RPi3 Models A+ and B+.  As expected the RPI3 Models A+ and B+ performed similarly with about 855 MB/s second while the RPi1 Model A+ ran at 97 MB/s which was 783 percent slower!  The biggest reason for this is the fact that the RPi1 Model A+ CPU is only running at 700 MHz with 256MB RAM whereas the RPi3 CPU is running at 1400 MHz with 512 MB (A+) and 1 GB (B+) RAM.

 

 

The following results were obtained using sysbench running speed tests in read mode on both Raspberry Pi3's set at 4 threads or cores:

 

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    RPi3 Model A+ Memory Read running 4 cores                                 RPi3 Model B+ Memory Read running 4 cores

 

As expected, with all 4 cores exercised the RPi3 Models A+ and B+ perform similarly at about 2924 MB per second.

 

 

 

The following results were obtained using sysbench running speed tests write mode on all three Raspberry Pi's set at 1 thread or core:

 

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    RPi3 Model A+ Memory Write running 1 core                 RPi3 Model B+ Memory Write running 1 core                RPi1 Model A+ Memory Write running 1 core

 

With 1 core exercised the RPi1 Model A+ performed with significantly less throughput than both the RPi3 Models A+ and B+.  As expected the RPI3 Models A+ and B+ performed similarly with about 640 MB/s second while the RPi1 Model A+ ran at 68 MB/s which was 845 percent slower!  The biggest reason for this is the fact that the RPi1 Model A+ CPU is only running at 700 MHz with 256MB RAM whereas the RPi3 CPU is running at 1400 MHz with 512 MB (A+) and 1 GB (B+) RAM.

 

 

The following results were obtained using sysbench running speed tests in write mode on both Raspberry Pi3's set at 4 threads or cores:

 

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    RPi3 Model A+ Memory Write running 4 cores                                 RPi3 Model B+ Memory Write running 4 cores

 

As expected, with all 4 cores exercised the RPi3 Models A+ and B+ perform similarly at about 2275 MB per second.

 

 

3. WLAN Performance:

 

The following results were obtained using CrystalDiskMark 3.0.1 on a Windows PC connected to both Raspberry Pi3's via the onboard 2.4 GHz Wifi circuitry and to the Raspberry Pi1 through a 2.4 GHz USB dongle.  These tests measure sequential file throughput in both directions.  The U3 Sandisk microSD is specified at a minimum of 30 MB/s speed for both read and write.  As a baseline, I measured the throughput of the microSD card on the PC through the USB 3.0 interface and recorded a 43.92 MB/s Read and 42.33 MB/s performance. This therefore represents the upper limit of the testing capabilities for this setup.  In other words, as long as any results I get with the Pi is less than 42 MB/s I know that the microSD card is not bottle-necking the Pi results.

 

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    RPi3 Model A+ 2.4 GHz Wifi

 

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    RPi3 Model B+ 2.4 GHz Wifi

 

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   RPi1 Model A+ 2.4 GHz Wifi     

 

Surprisingly at 2.4 GHz, the RPi3 Model A+ with a 7.8 MB/s read (Pi to PC) and 7.5 MB/s write (PC to Pi) throughput shows better performance over the RPi3 Model B+ with a 6.2 MB/s read (Pi to PC) and 5.6 MB/s write (PC to Pi) throughput.  Although they use the same 2.4 GHz Wifi hardware maybe the 1 Gb ethernet hardware on the RPi3 Model B+ is sharing some CPU cycles and therefore slowing down the Wifi throughput.  The RPi1 Model A+ shows a little better performance with a 8.0 MB/s read (Pi to PC) and 7.6 MB/s write (PC to Pi) throughput when using the Onnetworks 2.4 GHz Wifi dongle. 

 

 

The following results were obtained using CrystalDiskMark 3.0.1 on a Windows PC connected to both Raspberry Pi3's via onboard 5 GHz Wifi circuitry:

 

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    RPi3 Model A+ 5 GHz Wifi

 

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    RPi3 Model B+ 5 GHz Wifi

 

The 5 GHz mode on the RPI3s show a marginal improvement in throughput over the 2.4 GHz mode.  Again the RPi3 Model A+ with a 10.6 MB/s read (Pi to PC) and 8.7 MB/s write (PC to Pi) throughput shows a little better performance over the RPi3 Model B+ with a 10.0 MB/s read (Pi to PC) and 8.2 MB/s write (PC to Pi) throughput although this difference is not as pronounced as in the 2.4 GHz mode.

 

 

4.  Boot Time:

 

Boot time was measured at 14 seconds for the Raspberry RPi3 Model A+, 14.8 seconds for the Raspberry RPi3 Model B+ and 31 seconds for the Raspberry RPi1 Model A+.  As expected, both RPi3's showed similar boot times while the RPi1 Model A+ was much slower.  In fact, the Raspberry RPi3 Model A+ shows a 121.43% improvement in boot time over the Raspberry RPi1 Model A+.

 

 

5.  Power Performance:

 

Power measurements were taken using the P4460 KillAWatt Power Meter connected to the 5 VDC adapter and in conjunction with the CPU performance tests previously described.  The efficiency of the 5 VDC adapter was calculated by connecting a 10 ohm load to the 5 Vdc output of the adapter and reading the corresponding P4460 value and determining the difference from 2.5 Watts.  This calculated efficiency is 73%.

 

The readings annotated below were therefore adjusted by .73:

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There was a 0.55 W draw at standby for both the RPi3 Models A+ and B+ vs. a 0.26 W draw for the RPi1 Model A+.  This behavior reflects input design differences among these models.  Apparently, the additional hardware placed on the RPi3 versions result in a doubling of the standby power draw.

 

At idle, there is a 0.58 W draw for the RPi1 Model A+ vs. a 1.2 W draw for the RPi3 Model A+ vs. 2.56 W draw for the RPi3 Model B+ with Ethernet, HDMI and keyboard dongle connected.  Also at idle, there is a 0.66 W draw for the RPi1 Model A+ vs. a 1.1 W draw for the RPi3 Model A+ vs. 2.41 W draw for the RPi3 Model B+ in the headless mode and Wifi dongle (RPi1 Model A+ only) connected.  As expected, the more hardware onboard results in proportionately more idle power consumption.  In all categories the RPi1 Model A+ results in the lowest power consumption.  The RPi3 Model B+ shows the largest power draw since it contains the 1400 MHz 4-core CPU plus many other onboard modules, such as, WiFi, POE, 1 GHz LAN and 4 USB 2.0 ports.

 

At 1 core full load,  there is a 1.31 W draw for the RPi1 Model A+ vs. a 1.83 W draw for the RPi3 Model A+ vs. 3.25 W draw for the RBi3 Model B+ in the headless mode.  As expected the RPi1 Model A+ shows the lowest power draw because of the lower CPU frequency of 700 MHz. The RPi3 Model B+ shows the largest power draw because in addition to the 1400 MHz CPU it also has a bigger RAM module at 1 GB vs. 512 MHz for the RPi3 Model A+.

 

At 4 core full load,  there is a 3.65 W draw for the RPi3 Model A+ vs. 4.89 W draw for the RBi3 Model B+ in the headless mode.  Again the RPi3 Model B+ shows the largest power draw because in addition to the 1400 MHz CPU it also has a bigger RAM module at 1 GB vs. 512 MHz for the RPi3 Model A+.

 

The RPi1 Model A+ seems to be the most power efficient of the three SBCs.    Although the power consumption increases for the RPi3 Model A+ are reasonable considering the increased performance and capabilities realized.

 

 

7. Temperature Performance:

 

Temperature measurements were taken by opening a separate Raspberry Pi SSH window on the PC and periodically running the command:

 

"watch vcgencmd measure_temp"

 

The ambient temperature during these measurements was 17.2 degrees centigrade:

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At idle the RPi1 Model A+ was 4.1 degrees C cooler than the RPi3 Model A+ and 12.2 degrees C cooler than the RPi3 Model B+ in both headless and HDMI modes. Again as expected the RPi1 Model A+ shows the lowest CPU temperature because of the lower CPU frequency of 700 MHz. The RPi3 Model B+ shows the largest CPU temperature because in addition to the 1400 MHz CPU it also has a bigger RAM module at 1 GB vs. 512 MHz for the RPi3 Model A+.   Here again the RPi1 Model A+ is the winner with the coolest idle temperature.

 

At full load the RPi3 Model A+ is 0.6 degrees C hotter than the RPi3 Model B+ in 1 core mode and 5.4 degrees C cooler in the 4 core mode.  The RPi1 Model A+ ran 14.2 degrees C cooler than the RPi3 Model A+ in the 1 core mode.

 

As expected the RPi3 Model B+ ran hotter than the RPi3 Model A+ in the 4 core mode because it has double the RAM.

 

Here again the RPi1 Model A+ is the coolest and with the 4 cores of the RPi 3B+ it is significantly hotter.

 

 

 

Conclusion:

 

The new Raspberry Pi 3 Model A+ is quite impressive and significantly outperformed the previous RPI1 Model A+ with only a marginal increase in power consumption and CPU temperature.  The 700 MHz CPU speed increase, the addition of 2.4/5 GHz Wifi, upgrade to 512 MB RAM and addition of the aluminum heat-spreader are all welcomed improvements.  The small additional power draw and increase in CPU temperature penalties are well worth the performance gains realized. 

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