Author Archives: garreth

Arduino Variable Types Explained

Here’s something for reference.
I can never find just quite the succinct reference to Arduino Variable types. Nowhere could i find a list of minimum and maximum values, the bits, and the memory used by each variable type.

Neither was there any clear definition of meaning of ‘unsigned’, which just means no plus or minus signs in this type – that is all numbers positive. This increases the highest number that can be stored in the same memory. (thank me in the comments).

Usage Variable type Bits Min value Max value Ram usage Comments
common boolean 8 TRUE FALSE 1 byte
common byte 8 0 255 1 byte
char 8 -128 127 1 byte  A single ‘character’ e.g. ‘a’ is a single char.  Represented by chr(65) or the binary: 01000001
word 16 0 65535 2 byte
common int 16 -32768 32767 2 byte
unsigned long 32 0 4,294,967,295 4 byte
common long 32 -2,147,483,648 2,147,483,647 4 byte
common float 32 -3.4028235E+38 3.4028235E+38 4 byte
The below types are only included for compatibility or further study.
redundant unsigned char 8 0 255  1 byte use byte instead
redundant unsigned int 16 0 65535  2 bytes use word instead
redundant double 32 -3.4028235E+38  3.4028235E+38  4 bytes use float instead
The below types are special types (see arduino.cc)
special string variable  1 byte + x An array of chars
(used for storing strings to modify)
special enum variable  N/A Like boolean but custom fixed set of values allowed instead of TRUE/FALSE.
special struct variable  N/A Public sub variables
(as if you’d made a public class)
special pointer  N/A I’ll be honest, I wasn’t sure the use of this one. Here for completeness though!
Source: https://learn.sparkfun.com/tutorials/data-types-in-arduino
Source: https://playground.arduino.cc/Code/DatatypePractices
Remark: “Unsigned” means no negative sign. This increases the range of positive numbers available.
Remark: Unsigned variables that exceed their capacity roll over back to zero. This could be useful to iterate through arrays of limited length

PPS If anyone can figure out how to properly format this table so it looks nice, with ‘center’ aligned text, please let me know wordpress was being frustrating!

(The formatting css is in the source, see the table tag)

Find Windows workstation logon script

This is a super quick tip from an online forum…
[Sevenforums.com: Where is the location for the windows logon script?]

If you’re looking for the location of the active logon script in a Windows domain network on a workstation, or just to figure out which logon script is being used for a workstation

TLDR; ‘Get to the point, where is the bleeding thing?!’:

To find the location of a user’s logon script, while logged in as the user, run the command:
net user “%USERNAME%” | find “Logon script”
or for a domain user,
net user “%USERNAME%” /domain | find “Logon script”

Standard location

The logon scripts themselves can be found on the network in the standard domain network share location:

\\%USERDOMAIN%\netlogon

Additionally, the commands:

net user “%USERNAME%” /domain

and

gpresult /r

Give interesting results for the current user and what Group policy rules are active for the currently logged in user/(machine?) respectively.

Obviously this is only relevant to windows computers in active directory with primary domain controller and group policy ordaining that each machine should run a logon script.

 

Search Terms:

Things i searched for in order to try and find this out:

  • find out what logon script a computer is using
  • find path of logon script from workstation
  • find path of logon script from workstation registry

(I couldn’t find the registry location as it turns out!)

If this post helped you, or you have additional tips, please leave them in the comments!

Excel tip – adding two numbers where one is text

Just a quick tip as i couldn’t quickly find the answer in google.

If you have two cells of data and you want to add them when one might have text instead of a number, use the SUM function.

For instance

Class Section 1
QTY
Section 2
QTY
Totals
Robots 10,000 1,000 =sum(B2:C2)
=11,000
Humans 9,000,000,000 n/a =sum(B3:C3)
=9,000,000,000
Plants n/a n/a =sum(B4:C4)
=0

I also searched for: sum two values if isnumeric, excel add two numbers if text only include the non text and excel add two numbers if text.

Three Mobile Hotspot MITM Attack?

image

Is three performing a Man In The Middle SSL attack/proxy on my mobile hotspot?

Loading paypal:

image

Well hello NSA & GCHQ lol.

Funnily enough after searching Google for this issue and then retrying I don’t get some asshat trying to proxy my SSL connection. Or if they are they have a ‘genuine’ root certificate from a valid CA.

Project Teaser

image

Heres a little something that has come about from a related project I have built (and need to test)

Maybe I’ll write up both projects together!

Relevant hashtags #RaspberryPi #HTML5  #WS2812b
😉

R.A.O.K

An explanation more beautiful than my words could ever be:
Giving Is The Best Communication – Thai Mobile Ad…: http://youtu.be/JPOVwKPMG8o

The World full of horrible injustices, life is cruel and unfair. Survival of the fittest is now survival of the richest.

And the worst thing?
It feels like you’re just too powerless, poor or insignificant against the size if it.

Starvation, Cancer, HIV, Natural disasters whatever.

Well the truth is there is something you can do to change the world.

And its cheap, and simple and should make someone smile.

Its called A Random Act Of Kindness or RAOK.

Just do one small thing to improve the life of a stranger.
See that a Girl sobbing? Go give her a tissue.
Give your elderly neighbour a Christmas card or invite him round for a cup of tea.
Hold the door open for someone.
Carry a lighter just in case someone asks for a light.
Give out free hugs (I did this once. It was hugely fun. I made sure I got all the people with the saddest expressions 😉 ).

Have a think. Be good to people, even if you don’t know them.

Simple
Leave a note that says ‘pass it on’

Now you may never know the difference that a small random act of kindness makes to that stranger. But this is not about fame or fortune, its about changing the world one small random act of kindness at a time.

My hot tip? Why just one RAOK?

Share the love.

And Dear stranger,
If you find this, pass it on, and have a brilliant week!
Sincerely,
Anon
(I know my name is on here, but who I am doesn’t matter. Thank me by doing a RAOK and asking them to pass it on 😉 )

Link

Just a super-quick post here.

If you’re looking for addons or plugins for Microsoft Outlook to help you organize your emails and extend the functionality of Outlook

(note Outlook is very extensible, as with all Microsoft Office applications you can write Visual Basic code for Applications to hook into it’s functions. Absaloutely fantastic for hacking excel as I have been doing for the last few weeks – my work needs to invest in a proper database program for sure *sigh*)

You’d do no better than looking here

Snapfiles Outlook Add-ons

http://www.snapfiles.com/freeware/comm/fwoutlook.html

 

They have addons that are useful – and unlike most of the sites on i’ve found so far – up to date and compatible with recent versions (2003+) of Outlook.

Hope this helps folks!

 

Rfduino Chip vs Thermometer

Well, I’ve now debugged a few issues with my scripts from my last post.
(made them a bit more fault tolerant and actually take notice of $? exit statuses) .
Recap: Temperhum (USB) -> Raspberry Pi -> Xively chart, now also
RFDuino (bluetooth wireless) -> Raspberry Pi -> Xively chart

Tip:  If you’re struggling with the bluetooth on linux giving rx timeout errors (check the syslog if it’s not in the console),
update the software with the following commands:

sudo apt-get update
sudo apt-get upgrade

The Rfduino has been sitting next to my usb Temperature and Humidity sensor for a few weeks collecting data.

IMG_20140514_223244041r

RFDuino and Temperhum

Since it had been both collecting data for a few weeks and sending them to Xively / Pachube / Cosm, I had a quick look to see how closely the readings match.

Rfduino vs thermometerr

The graphs do show correlation, thank goodness, but it looks like the RFDuino’s temperature scale isn’t right. The RFDuino is only updating the graph once a minute whereas the Temperhum is 2x a minute.

I didn’t really expect great accuracy for the RFduino thermometer seeing as it’s measuring from the chip. But this would still be useful in some more basic cases.

I think next on the roadmap for the RFduino is connecting sensors/remote controls (it would be cool to attach my RelaySockets to this and control the 2 connected relays via bluetooth from my Pi and Android smartphone!

 

My Humidity and Temperature sensor

A Temperhum from PCSensor.

A great little bit of kit – once you work out the conversion values for the C++ USB/i2c/HID code that lets linux talk to the thing!