Raspberry PI camera, quick guide

For those who want a real lowdown right away, here is the final verdict, as of the time of writing this, there are no faster options, the limitations here are imposed by the creators of PI and it’s chips (The Broadcom GPU)

You have 2 options for capturing stills in burst mode. In the case i am addressing here, taking photos of rapidly moving objects in broad daylight, so the shutter speed is very fast, the ISO is not so high (Because of the sun).

1- Through the GPUs stills part of the processor, you would get less than 2 frames per second, you can use the timelapse function.

2- Through the video port on the GPU, this will allow a maximum of 15 frames per second at 5MP resolution, no binning, no sensor cropping, but the still port gives somewhat better photo quality

Considerations

The speed of storage counts, if your storage becomes a bottleneck, 15FPS will not be possible.

1- You can use faster USB storage, the USB port is bound to a maximum of 45MB/Second

2- A fast memory card, currently 25MB/s comes on expensive “Professional” SD cards, i would rather use the USB port

3- Splitting the bandwidth between storage and Ethernet is not a good idea, the Ethernet adapter on the raspberry PI is connected through USB, so it will share the USB bandwidth 😉

4- Splitting the storage or buffering some of the frames on the SD card can be a good idea, as the SD card is connected directly to the CPU not through USB

5- Lowering the photo quality through increased performance will give you good mileage, something equivalent to what other programs call 80% quality will reduce the size pretty well without sacrificing much.

How to get through the stills port

raspistill -o %04d.jpg -ss 5000 -ISO 300 -t 10000 -tl 100 -q 10 -th none

So, the questions that come to mind instantly are, how come quality is a value from 0 to 100 and we are using 10 ? it is a good question, and this is something that is not making sense i know, but judging with my eyes, -q 10 will give us good compression ratio and the photo is still good, the range between 10 and 100 does not make much difference, and then under 10, things go very bad rapidly, no idea why

Now to the next method, which is getting photos from the video port… here is a quick and dirty picamera python script

If you don’t know how python works, please don’t change the indentation, indenting the print statement will add the print to the previous code block which is something we don’t want.

#!/usr/bin/python3
import time
import picamera

frames = 60

with picamera.PiCamera() as camera:
    camera.resolution = (2592, 1944)
    camera.shutter_speed = 5000
    camera.iso = 100
    camera.framerate = 10
    camera.start_preview()
    time.sleep(2)
    start = time.time()
    camera.capture_sequence([
        '/usbstick/image%02d.jpg' % i
        for i in range(frames)
        ], use_video_port=True)
    finish = time.time()
print('Captured %d frames at %.2ffps' % (
    frames,
    frames / (finish - start)))



So simply put, if you are running raspbian, you need to get into the pi config (command is raspi-config), and enable the camera then reboot

Also, don’t forget to run “rpi-update” or apt-get upgrade

Now if you try to take a photo you would enter the command

raspistill -o cam.jpg

But this will take a long time to take one photo (5 seconds by default), this is because it needs to set the exposure, if you want to give it less time you could run the command

raspistill -t 1500 -o test.jpg (One and a half seconds)

But that’s is too long, i already know that it is broad daylight, and that i need a very fast shutter speed, So how do i manually set things ?

Taking a photo of fast moving things in the SUN, i would run the command as follows

raspistill -t 1 -ss 1000 –awb sun -o test1.jpg

Taking photos of moving things in cloudy weather, i would run the command as

So, here are the manual things

–ss 1000 (1 ms, good for a sunny day oudoors, 4ms is good on a cloudy day, with dim light, i would recommend bumping this up a bit)

–ISO 300 (Sensitivity, Back in the day, the film dictated this property), the faster the shutter (Lower value), the higher the needed sensitivity (ISO VALUE), the range is 100 to 800

–nopreview

Prsets for Automatic white balance (AWB)

–awb sun

APC is gone, drop in replacements here

APC is gone, no longer maintained, now there are alternatives.

For opcode cache, PHP 5.5 (5.6 shipps with jessie) the opcode cacher ( OPcache ) module is installed and enabled by default, as for key cache (Persistent across pages), we have an alternative called APCu (Just the user key value cache), once installed, the apc_ functions return to PHP so it is a drop in replacement, no no program modifications needed.

To install APCu, you run the following

1- Install the tools
apt-get install apache2-threaded-dev php5-dev php-pear make
2- Before you get APCu-4.0.7, you should check what the latest version is !
pecl install channel://pecl.php.net/APCu-4.0.7

Now you are done, all you need to do is add
extension=apcu.so
to the php config file, in my case, what i do on debian jessie is add it in a file here
/etc/php5/apache2/conf.d/apcu.ini

There you have it, you are back on track.

Upgrading Debian from wheezy to jessie

It is simple, but i am issuing no guarentees, this will probably work for you, but there is a chance that something could go wrong, you have been warned

Loosing network connectivity: One thing that sometimes happens is that the Ethernet number can change from eth0 to eth1 for example (this could happen if your system has not been exposed to other cards, in which case it can turn from eth0 to eth6), What you can do about this is either be physically present to fix it (fix in /etc/network/interfaces) or add another interface to the file so that it can work out of the box, or have KVM over IP, or something of the sort, if you have LXC installed, the containers will not be able to fire up because they must have the following two extra lines in their config, /var/lib/lxc/CONTAINER_NAME/config

lxc.autodev = 1
lxc.kmsg = 0

apt-get update
apt-get dist-upgrade

edit your apt sources (vi /etc/apt/sources.list)

replace the word wheezy with jessie (Wherever you find it)

apt-get update
apt-get dist-upgrade

You should be done

Installing enhanceio on debian Jessie (Not wheezy or squeez, minimum kernel 3.7 onwards)

Using enhanceio (the flashcache fork)

First, on a debian system, you need to compile enhanceio because debian have not yet released anything for it (2015-05-13)

apt-get install git make gcc pkg-config uuid openssl util-linux uuid-dev libblkid-dev python
apt-get install build-essential
apt-get install linux-headers-$(uname -r)

Now let us download enhanceio

git clone https://github.com/stec-inc/EnhanceIO.git
cd EnhanceIO/Driver/enhanceio/
make && make install

On make install you will see
make[1]: Leaving directory '/usr/src/linux-headers-3.16.0-4-amd64'
install -o root -g root -m 0755 -d /lib/modules/3.16.0-4-amd64/extra/enhanceio/
install -o root -g root -m 0755 enhanceio.ko /lib/modules/3.16.0-4-amd64/extra/enhanceio/
install -o root -g root -m 0755 enhanceio_rand.ko /lib/modules/3.16.0-4-amd64/extra/enhanceio/
install -o root -g root -m 0755 enhanceio_fifo.ko /lib/modules/3.16.0-4-amd64/extra/enhanceio/
install -o root -g root -m 0755 enhanceio_lru.ko /lib/modules/3.16.0-4-amd64/extra/enhanceio/

cd /lib/modules/3.16.0-4-amd64/extra/enhanceio/
insmod enhanceio.ko
insmod enhanceio_fifo.ko
insmod enhanceio_lru.ko

#Now check that it is loaded as a kernel module with (HINT: Will it be there after reboot ?)
lsmod | grep enhanceio

cd ../../CLI/
cp eio_cli /sbin/
cp eio_cli.8 /usr/share/man/man8

Now that we have installed and compiled enhanceio, we will simply use it, we are all done, unlike bcache and dmcache, there is minimal setup for this kind of ssd/flash thumb stick.

Now in my setup, i want sdb to act as an SSD cache for sdc1

eio_cli create -d /dev/sdc1 -s /dev/sdb1 -p lru -m ro -c main_disk_cache

The output of that command was as follows, this result can also be obtained with the command “eio_cli info”, or for super detail “cat /proc/enhanceio/main_disk_cache/stats”

Cache Name       : main_disk_cache
Source Device    : /dev/sdc1
SSD Device       : /dev/sdb1
Policy           : lru
Mode             : Read Only
Block Size       : 4096
Associativity    : 256
ENV{ID_SERIAL}=="WDC_WD1001FALS-00J7B0_WD-WMATV0098355", ATTR{partition}=="1"
ENV{ID_SERIAL}=="INTEL_SSDSA2CW120G3_CVPR1481061P120LGN", ATTR{partition}=="1"
Cache created successfully

Now to see the block size
blockdev –getbsz /dev/sdb1 (512 was the result)

The ADATA S596 64GB SSD (500 series)

The controller on this SSD is the jmf612, along with the RAM chip (Cache) hynix H5PS1G63EFR (SDRAM) (64m X 16BIT) = 1Gbit which is 128MB (128 MBYTE).

This chip does not suffer from the latency problem in the JMF601A/602A chips, (jmf612 is 2009 while JMF601A is 2006).

The memory that comes with the drive is made by intel (29F32G08AAMDB), 4GB per chip, With 16 such chips, we have 64GB of flash on the board, the photos will follow once i get them off my camera and onto this blog.

The reason why i am keeping record here is that this drive is probably going to be used as a bcache cache device, and i am concerned about reliability, Granted that it is 90% read scenario, some websites are claiming that data corruption is a downside, but not providing any elaboration, http://alatest.co.uk/../corsair-reactor-r60-jmicron-jmf612-ssd/po3-116271270,383/ (The crosair reactor-r60 is identical to this drive)

The drive is claimed to have speeds of read 240 write 170, compression is not a factor in this as other drives use compression to gain speed, something that is only good for certain types of data

There is also a new firmware at the adata website that you should make sure is installed, ADATA S596 Firmware Update Tool V1.0

NOTES:
Drives with this controller include

  • Patriot Zephyr SSD
  • Corsair Reactor-r60
  • Active Media Predator-X7
  • Western Digital SiliconEdge Blue
  • Kingston V-series

Advanced Linux SSD caching for hard drives on Debian Jessie – bcache and enhanceIO

Please note, i am keeping this thread for myself as a reminder, so if sometimes you feel that it is getting too general, it is probably more of a reminder for me.

Also note that i am organizing this post as i go as i spend some time creating my new MySQL machine every day, so this is an ACTIVE work in progress

—————————————————
First note, the benefits of RAID 0 on the SSDs is more about wear than it is about speed.
Here is why and how

1- All modern disks use wear leveling to prolong the life of your disk, bcache does nothing in this regard, so using thumb drives is not very smart.
2- Your SSD has to be larger than the active data set, otherwise, bcache or any other will start kicking out data and writing in it’s place too often, wearing your disk, yet, if the data that is always accessed on your hard drive is about 500GBs of your 3TB disk, and your cache drive is more than 500GBs, odds are that your disk will probably send this data, then spin down because everything we need is already on the SSD reducing the wear to almost nothing. If you do not have a large enough SSD, odds are you will save their life with a RAID setup, either software or hardware, it makes no difference.
3- Larger disks have longer lives in general with or without raid for all purposes, the reason is arithmetically simple, the larger the disk, the linger it takes for a flash chip to get it’s turn for a write again because the others need to get their turn first, the larger the disk, the more the banks, hence, the longer the useful life.
4- Erase commands are expensive, And even with a workaround, trim support means nothing on a busy server
—————————————————
My own setup

1- My computer has 6 sata ports (ASUS P9X79).
2- I prefer to never group spinning hard drives in one metal case that does not have vibration isolation, so the mainboard SATA will host the 5 SSDs, and the main hard drive (2TB black).
3- I have 2 PCIe 2 port esata cards (silicon image supporting port multiplier)
4- 1 SATA port multiplier (Silicon image) that even though has raid function, is probably more reliable in JBOD mode, where the 5 spinning disks other than the main disk will need to live.

Most data on the 6 spinning disks is only stored and seldom accessed. furthermore, most of this data does not get cached because it is accessed sequentially.

The boot partition of the hard drive (Spinning) is not cached, the second partition is, this is safer as the system can boot anyways, then the raid array and the bcache initialized with no unforeseen effects, boot time is not so important as the PC is always on, we reboot it once a year

—————————————————
Note for self:
1- What are the possibilities of 2 cache layers, one with write-back, the other is only for read cache.
Possible Advantages:
You can use less reliable flash thumb drives with no wear leveling mechanism as an extra cache layer, where failure will not cause data corruption, but will leave more space for the SSDs
Overcache problem considerations ?
The SSD will initially get the same cache as the thumb drive, but when the hit rate on the thumb drive increases, the SSD will remove that data, so we will only have 1 copy
The SSD with write-back can make writing a hell lot faster for database data.
Bcache only allows one SSD per spinning partition. you can not combine, while the other methods could ! and since they are read only, you could even RAID the thumb drives
Caching software available
Device mapping
bcache (part of the new kernels)
dm-cache (part of the new kernels)
Flashcache (Facebook’s)
EnhanceIO (Fork of flashcache)

EnhanceIO can be attached to any block device on-the-fly even
when device is already mounted.
dm-cache is faster, but bcache is safer

If so…
we will probably be using bcache in FIFO mode, and enhanceio in most (least recently used (LRU)).

Also take a look at https://github.com/Feh/nocache
—————————————————
You probably noticed that there are not many tutorials and instructions on bcache for Debian online, the reason is that the user tools are not packaged for Debian, not even for Jessie, but that is a simple thing, the hard part has already been done at the kernel level so you dont need to recompile the kernel, but you need the instructions on how to setup bcache !

So here is a step by step, no theory and no explinations, just the procedure

bcache, the simple and safer way

So here is how i setup bcache on my linux server for MySQL usage.

1- create 2 partitions on my 2TB disk, one would be 200GB and the other 1800GB (With fdisk or parted you chose)

2- Delete the first 200GB partition leaving only the other

3- Run the debian installer and instructing it to use the continuous free space, which is now the small first partition

apt-get install git make gcc pkg-config uuid openssl util-linux uuid-dev libblkid-dev

git clone https://github.com/g2p/bcache-tools.git

cd bcache-tools

make

make install

-------------------------------------
install -m0755 make-bcache bcache-super-show /usr/sbin/
install -m0755 probe-bcache bcache-register /lib/udev/
install -m0644 69-bcache.rules /lib/udev/rules.d/
install -m0644 -- *.8 /usr/share/man/man8/
install -D -m0755 initramfs/hook /usr/share/initramfs-tools/hooks/bcache
install -D -m0755 initcpio/install /usr/lib/initcpio/install/bcache
install -D -m0755 dracut/module-setup.sh /lib/dracut/modules.d/90bcache/module-setup.sh

-----------------------------------------------------

Now, use wipefs to delete the filesystem on the big partition (/dev/sda2) so that we can format it as bcache rather than ext4

wipefs -a /dev/sda2

Take note of the UUIDs that come out of thie following 2 commands.

Why ? well, caching devices are the SSDs, backing devices are the normal sata disks, what happens when you run the following 2 commands is that you tell the kernell that one is a backing device, and the other is a caching device, you can have as many backing and caching devices as you want, but pay attention to this, you can not use 2 SSDs to cache one disk, although you can use 1 SSD to cache multiple disks, so for example, you can have 2 SSDs caching 5 disks, 1 SSD can cache 3 disks for example and the other can cache 2 disks.

Also, this is debian, so this step is done for you automatically, you will have /sys/fs/bcache/somediskuuid off the bat, that does not apply to all linux systems (some systems might requiere you to do the following to the backing deice ... echo "the bcache uuid" > /sys/fs/register)

First step, initialize my 1.8TB partition into a bcache block, -B means this is a backed device

make-bcache -B /dev/sda5

mkfs.ext4 /dev/bcache0

Then initialize the SSD (120GB intel SSD) into a bcache block, -C means caching device

make-bcache -C /dev/sdb1

--------------------

UUID: 4e9aed54-bf48-4d7a-b5b2-b041f2a811f8
Set UUID: 13544b4e-99de-42a0-905a-c6efbe669151
version: 0
nbuckets: 228944
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1

----------------------------

Now we have a backing and caching device, let's connect them together, this step is called "attaching"

first,

cd /sys/fs/bcache/

ls

the ls command will give you the caching devices UUID as a folder, which is actually a folder.

Now, Mount the bcache partition.

mount /dev/bcache0 /hds/cacheddisk (Check that you have bcache0 not bcache1 for example).



Macbook Pro and the battery problem

A friend of mine had a problem with a MacBook Pro, the problem was that it would not turn on, so i took a look at it and here is what i came up with

The battery was completely dead, effectively disabling the SMC (System Management Controller).

Without the SMC, the system will refuse to boot unless you bypass the SMC.

To bypass the SMS and make the computer run, you do the following

1- Disconnect the power cable.

2- Hold down the power button for 10 seconds (or more), then while still holding the power button down, connect the power cable and keep the power button pressed down for another 10 seconds (or more), then once the 20 seconds are over (10 without cable and 10 with cable), release the button and press it again like you normally would to start the computer.

Your fans will run at full speed (resulting in a loud computer), it will be slow, and it might crash or restart itself, in short things will not be working fine, what you need is a new battery.

------------------------------------------------------------
Stuff that only applies to my friend, so skip this part
------------------------------------------------------------
Here are the specs of my friends laptop.

meera1

When you want to look for a battery online, you should be looking for

Macbook Pro A1286 Early 2011 battery (Does not apply to all readers).

I did a search, but knowing that you will be taking it to a service person to install it means that a bad choice on my end (even with a money back guarantee) could mean paying twice to the repair person, so it is not as simple as it seems for me (Since you won't be installing it yourself).

The original battery (OEM) costs $110 it seems, batteries from other providers seem to cost anywhere from $25 to $70, with the $25 batteries having super bad reviews, and the ones for $70 being ok it seems. still, the complications (having to take it to someone to install it) leave me confused. so a safe bet would be the OEM (Original apple battery) but then that's more than double the price
------------------------------------------------------------

Once you install the new battery, you will need to reset the SMC, the repair shop will probably do the reset for you, but just in case.

Shut down the computer.
Plug in the power adapter.
On the built-in keyboard, press the Shift, Control, and Option keys on the left side and the power button, all at the same time.
Release all three keys at the same time.
Turn on the computer.

You are done

Google talk stopped working, make it work again

Google talk stopped working today, but i am so used to it, i don’t think i can live without it.

When i try to login, it says, username and password do not match, (You provided somename).

So here is the plan to make google talk work again.

PLEASE LEAVE A COMMENT IF YOU WOULD LIKE ME TO MAKE THIS SERVICE PUBLIC

The google talk installer is all over the internet, google talk uses XMPP as a protocol

I will be creating a server, and creating a file to make google talk connect to my server

Now i will tell all my friends to register their existing email address with this server and to run the file that changes the server for google talk, and we should be back online again

I will be monitoring my own instance of google talk for incoming and outgoing data so that i can modify the server so that it would become fully compatible since google talk is not 100% XMPP.

I will keep everyone posted on this. Hopefully i will have it working by the end of the day

lead acid batteries – all about

Because i use lead acid batteries on my UPS systems, i will be putting all the relevant information that i need on lead acid batteries here

1- What does 74ah (74 amp per hour mean)
In most cases, it means 3.7ah over 20 hours, so you can draw 3.7 amps for 20 hours before the voltage drops to 10.5V, the equation is not linear, so basically you will be able to draw less than 7.4ah in 10 hours (Less than double for half the time), the rating is usually 20 hours on most batteries, the Bosch car batteries (S3 S4 S5…) are measured for 20 hours for example.

The CCA are usually measured for a 10 second period until the voltage drops to 7.5V (Yes, minimum of 7.5V not 10.5)

Now, sometimes, i connect an inverter and a power supply and a battery together, so that the inverter draws from the power supply, while the battery is technically maintaining its charge, if you can’t control the current, and just want the charge to stay put, something between 12.6 and 12.7 is a good voltage, but to be on the safe side, fully charge your battery, then let it sit for 24 hours, then get a voltage reading, tune your power supply to that voltage, and connect them all together.