Performance Comparison of a few Computer Systems

Small computer modules like the Tinker Board now easily outperform old laptops while the cost ratio is 1:20.

Why is that Tinker Board runs so much faster?  Compaq Presario 2100 laptop (2003) has an Intel Celeron processor, from the Wikipedia,

Model Number	sSpec Number	Frequency	L2 Cache	FSB	Mult	Voltage	TDP	Socket	Release Date	Part Number(s)
Mobile Celeron 2.0	SL6QH (C1) SL6VJ (D1)	2000 MHz	256 KB	400 MT/s	20×	1.3 V	32 W	PPGA 478	14 January 2003	RH80532NC041256

It has 1GB RAM (max possible).  The graphic processor is ATI Radeon.  The Tinker Board has 2GB dual channel LPDDR3 RAM and a Rockchip RK3288 processor (Quad-core ARM Cortex-A17, up to 1.8 GHz and Quad-core ARM Mali-T760 MP4 GPU clocked at 600 MHz, 1MB L2 unified cache ).  The board runs on less than 5W.  Note that while everything else has improved, the processor speed has not.

The Tinker Board also compares favorably against other similar boards.  It is reported that the Tinker Board is almost twice the performance as Raspberry Pi 3.  When compiling KiCad, the Tinker Board takes about 4 hours, vs 8 hours on OrangePi Prime.  This seems consistent with some benchmarks that OPiP has a little lower performance than RPi 3.  Perhaps this justifies the twice of the cost.  Furthermore, the board quality is better.  However, while OrangePi releases the full schematics, Asus only releases the partial schematics for the Tinker Board.  Comparing RK3288 vs H5, CPU speed 1.8GHz vs 1.37GHz, about 30% faster.  So that alone does not account for the difference.  RK3288 is 32-bit architecture ARMv7-A and H5 is 64-bit ARMv8-A  (Cortex-A53 Quad-Core, 512KB L2, Mali450 MP4 GPU).  Cortex-A17 features out-of-order execution and deeper pipeline than Cortex-A53.

On Core2 Duo T7200, compiling KiCad takes about 2.5 hours with a solid state drive with 3Gb/s SATA connection.

Model number	sSpec number	Cores	Frequency	L2 cache	FSB	Mult.	Voltage	TDP	Socket	Release date	Part number(s)
Core 2 Duo T7200	SL9SF (B2)	2	2 GHz	4 MiB	667 MT/s	12×	0.95–1.175 V	34 W	Socket M	August 2006	LF80537GF0414M

All these have been single core performance. If we use all available cores, Core2 Duo still outperforms the Tinker Board, but the difference is smaller, about 30%.  Multicore improves 2.2 times for the Tinker Board and 1.6 times for Core2 Duo.  On Atomic Pi,

Model number

sSpec number

Cores

Frequency

Burst

L2 cache

GPU model

GPU frequency

Memory

TDP

SDP

Socket

Release date

Part number(s)

Atom x5-Z8350

SR2KT (D1)

4

1.44 GHz

1.92 GHz

2 MiB

HD Graphics (12 EUs)

200-500 MHz

1 × DDR3L-1600

2.17 W

2 W

UTFCBGA592

February 2016

FJ8066401836620

running 4 cores (2M L2) at 1.68GHz, the compilation takes 2.3 hours, longer than the Tinker Board, which is a little surprising.  Core2 Duo T7200 and Atom x5-Z8350 receive similar CPU Mark, but single-thread rating is much lower for x5-Z8350.The system has the advantage of having a faster disk.  A further comparison, compiling KiCad on i9-8950HK (2.9GHz/4.8GHz turbo 12MB L3) Linux Virtualbox takes only about 45 minutes.

Product Failure II

Continued from product failure.

Power Adapter

5V 2.5A AC power adapter failed.  It was still able to provide about 0.5A, but larger load caused it to turn off.  The output capacitor showed sign of heat damage.  It was a 16V 1000uF by TEAPO, but measured to have only about 5uF capacitance.  After it is replaced, the adapter worked fine with 2.5V load.  It is unclear just what caused the capacitor to overheat.

ATOTO A6 Pro

As I add to my old car more electronics, GPS, backup camera, dash cam, Bluetooth, etc, I figure all that can be handled by the Android auto head unit.  I picked up ATOTO A6 Pro for about $220.  It has the following features:

• Model Name: A6Y2721PRB (2GB/32GB);
• SoC Chip: MTK 8127A Soc-based Quad-core 1.5Ghz Cortex-A7 (512K L2) CPU with ARM Mali-450 MP4  600MHz GPU.
• Pre-Amplifier: Built-in Max 4*49W BTL Amplifier with RMS 4*29W (Vcc=14.4v,THD=10%); It can drive both 4Ω & 2Ω door speakers! 
• Preset 9-band EQ with 12 section adjustable frequency;
• Bluetooth: Dual Bluetooth (BT1 5.0 & BT2 4.0). Bluetooth1 is Qualcomm Bluetooth 5.0 w/ aptX feature, and it supports HFP/HSP/A2DP/AVRCP/PBAP;
• Radio tuner: Built-in FM/AM Radio Tuner w/ RDS (station name will be displayed if available);
• Display: Full HD 7" 1024*600 5-Touch Capacitive Touchscreen with 600cd/m² latest 178° full-viewing angle IPS display screen;
• GPS/Navigation: Builtin GPS Receiver module with external GPS antenna
• WiFi/Microphone: Builtin microphone & Ultra external Wi-Fi antenna (Silver plated copper wire) and external microphone
• Input/output
• Reversing camera input
• Front camera input
• AUX Audio/Video input
• 4-CH RCA Audio Out (4V) for connecting to amplifiers
• Separate Sub-woof Out (4V) (Manual /Automatic mode available)
• Steering wheel control input
• One Micro SD slot
• 3 USB interfaces, one of which is a quick charge (2A) port

The harness has the following connections

This model has physical buttons, no gesture control.  Having physical buttons is useful because the it is harder to operate the touchscreen while driving.  But in any case, a rotary switch would be better for such things as changing volume. 

When ignition is off, it draws about 18mA.  The standard battery is 45Ahr.  So it is about 1% a day.   It takes 2 seconds to be on after the ignition is on.  When idle, it draws about 700mA.  When in standby, it draws about 330mA.

Installation is not too difficult after watching a number of online videos.

Car Startup Battery Energy and Recharge

One of my cars has been used for very short trips lately.  The question is whether the car battery can maintain full charge.  The starter is rated 1.7KW, but that could be continuous running power.  The start-up power could be higher.  Let's assume 500A for 3 seconds, that's about 0.4Ah.    The alternator rated output is 100A; but the actual charging current is much lower, no more than 1/4C, could be as low as 1/10C.  The battery rated reserve capacity is 100min (25A) , so the capacity is about 42Ah; then the charging current could be only 4A.  That means it should recover the loss energy in about 6min.  So if the trip is more than 6min, the battery should maintain the full charge.  This estimation is conservative.

Component Failures

Electronic components can fail in many ways. Here I try to document some failures that I've encountered.

Resistors usually fail open. I had a small gate resistor failed open, but I'm not sure if it failed because of a surge of current or a spike in voltage. I had an SMT 0805 resistor rated for 100V failed when 200V was applied to it. It failed slowly; I knew that because it was connected to an LED, and the LED faded and flicked a little before completely went out.  A current surge on a resistor may just change its resistance.  I had one current sense resistor increased its resistance by a factor 2 and another changed a few percent after current surge.  Another 50-milliOhm axial current sensing resistance increased resistance to 250milliOhms.

An aluminum can capacitor blew itself apart completely after it was applied with reverse polarity voltage. A 1000uF 16V aluminum electrolytic capacitor at the output of 5V 2.5A AC adapter appeared overheated and failed with reduced capacitance.   A ceramic capacitor fails short.  It happened on a cPCI power backplane, which had a 10uF ceramic cap on 12V and became a 4-Ohm short.

A diode in a PC power supply failed short, tripped the fuse.

A white LED was overstressed with larger than normal current for a long time.  It did not fail completely; but it flickered.  It ran fine with reduced current.

Power MOSFETs can fail short. Usually a check for the resistances between terminals if the MOSFET is alive; all should be high impedance except that the source-drain body diode may give a little lower reading (depending on the meter used) if measured in the forward polarity of the diode. A check of the source-drain body diode voltage is also a good test; it should be about 0.5V (also depending on the meter used) in the forward direction and no voltage in the other direction. I had a power MOSFET in a push-pull converter failed with a source-drain hard short and gate-source short with 420 Ohms resistance. It was probably killed with a surge of current possibly due to transformer magnetic saturation. Another one died with the body diode still intact. But there was finite resistance between the gate and drain; when it was powered, it simply shorted the drain and source. An examination of its TO-220 casing showed blisters on the metal tab.

Opamps can fail when the output is shorted. Some opamps are more resistant to output short. The output stage is destroyed when the output is shorted and excessive current flows. I had a gate driver failed when the output was shorted to the ground. The damaged IC had the supply pins shorted as well as the output pin shorted to the supply pins.

Inductors and transformers are not easily destroyed, but they can wreak havoc on the components connected to them.  Enormous voltages can be readily generated when they are switched.

Install TinyCore Linux without CD

Even some of light weight Linux distribution, such as Lubuntu is too much for old computers, which I think still have usable life left.   Recently I tried tinycore and was impressed by it.  Here is how to install it on a computer with a version of Linux already installed.  And we install it without using a CD drive.

TinyCore Linux is very flexible.  We can take the iso image and simply unpack it to /tce directory. We add a Grub entry to load the TinyCore image,

linux /tce/boot/vmlinuz
initrd /tce/boot/core.gz

This setup is by far the easiest and the most responsive Linux I've used.   The file /tce/onboot.lst specifies the list of packages that are loaded on boot.  We can edit it for customization.  Most applications should probably be installed as ondemand for fast boot.  I install chromium browser as ondemand.  It takes a few extra seconds to load, but the browser is usable.  The home directory is saved on exit and restored on boot.  However, if it gets too large, it can have a persistent storage location on disk.