Show Posts
Pages: [1] 2 3 ... 169
1  General Category / General Discussion / Re: HOW TO FIND PORT IN LINUX USE AT COMMAND on: October 26, 2013, 02:34:24 pm
I recently noticed a feature in CentOS 6 - if you look in /dev/serial/by-id/ you'll find a unique device special file name for FTDI based devices.  Not sure how long this feature has been there; I know I've had to use udev rules to get that functionality in the past.

If you are fortunate enough to have an Arduino with the FTDI USB interface, this gives you a unique repeatable device special file name no matter when or where or how many get plugged in.

If you've got a newer one that uses the Atmel chip for USB, then the device has no unique identifier so you're out of luck.

-j
2  General Category / General Discussion / Re: Need help with building a quadcopter! on: October 21, 2013, 05:53:38 am
Take a look at eCalc's multicoptor calculator:

http://www.ecalc.ch/xcoptercalc.htm?ecalc&lang=en

If you're using common components it is very easy to use.  If you're using components not on the list. you'll need some techincal data to feed the program .

-j
3  Development / Other Hardware Development / Re: Eagle - Many package connections to one device pin? on: September 11, 2013, 09:00:07 am
Quote
I looked at the @ option too but that seems to require a symbol pin for each connected pad. The example I have is a battery holder, so obviously I want a standard 2 pin battery symbol for the circuit...
I think you call the one on the symbol GND, but it will want all of the GND@X pins connected on the PCB.

You don't have to connect all of the pins to the device, so you can have GND, GND2, and + pins on the package, but only have GND and + on the device.  This would leave you with a permanently isolated pad on the board (so you have mechanical mounting) but no electrical connection.

For example, here's a coin cell battery holder from the Sparkfun eagle library that has a large SMT pad for one side of the battery and two through-holes which are electrically connected on the battery holder, but only one of them is connected in the library device and the results is the electrically isolated through-hole.



Is that what you're after?

-j
4  Development / Other Hardware Development / Re: Eagle - Many package connections to one device pin? on: September 10, 2013, 04:04:39 pm
There's a trick for that; IIRC it involves @ in the name.  e.g. pins GND@1 GND@2 GND@3 are all GND.

Do some googling and you'll find details.

-j
5  Using Arduino / Project Guidance / Re: Point an antenna at a static GPS location on: August 23, 2013, 06:06:47 pm
Quote
With all respect, oh great one, oh, yes they do.  You get a reasonablly accurate 'course direction', with respect to either magnetic, or true, north after warmup and reception of three or more satalites.

Wrong!

The GPS knows the course if it is moving.  If it isn't moving, it doesn't know.  Some units immediately revert to a course of 0, some hold their last estimate of the course.

If you want to know orientation when stationary, you need a compass.

-j
6  Topics / Education and Teaching / automated linux deployment in a shared home directory environment? on: August 22, 2013, 02:34:51 pm
Has anyone done automated mass deployment of the arduino environment on linux boxes, especially where  the user has an NFS mounted home directory?

Thinking about deploying in my labs, and I'm wondering if anyone else has done enterprise class installations, and if there are any gotchas if the user has a remote home directory.

-j
7  Using Arduino / Networking, Protocols, and Devices / Re: Reading from multiple UART´s on: August 16, 2013, 08:11:05 am
Got a part number?

Best I've seen is dual.  Quad would be awesome.

-j
8  Using Arduino / Networking, Protocols, and Devices / Re: Reading from multiple UART´s on: August 16, 2013, 06:24:09 am
Quote
kg4wsv, you are suggesting adding 20+ uarts for the arduino to control?

Yep.

Quote
That makes no sense.

It's what the OP asked for.

Besides, I use rack mount boxes that are 16 port RS232 to USB adapters at work, so it's not much of a stretch for me to imagine someone needing a crapload of serial ports.

Quote
An RS485 transmitter/receiver for duplex comms, or a transceiver for simplex, is all that is needed.

If he's building an entire system from scratch, I would agree.  But maybe he's got a bunch of COTS devices that already exist and only have RS232 that he needs to interface. Again, not hard for me to imagine, because I've got the same problem.

Your RS485 may be what he needs, but my pile of MAX3110s is what he asked for. smiley

-j
9  Using Arduino / Networking, Protocols, and Devices / Re: Reading from multiple UART´s on: August 15, 2013, 03:42:43 pm
Use an external UART, like the MAX3110 or MAX3111.  They use an SPI interface to the Arduino.  You'll have to use a multiplexer for the slave select to get that many devices on your SPI bus, but it is theoretically possible.

NXP also has some devices that are I2C or SPI, but they're 3.3V parts.

Another option is to use an Arduino as a UART peripheral.  You have to write the library on each end, though.

-j
10  Topics / Home Automation and Networked Objects / Re: Turn on the lights when gate opens - magnetic contact switch on: August 10, 2013, 06:41:28 am
Sounds like a 555 timer circuit.
11  Topics / Science and Measurement / Re: 12 bits of sweet resolution on: August 09, 2013, 07:14:58 pm
Did you put a meter on the ADC input to verify?

-j
12  Topics / Science and Measurement / Re: 12 bits of sweet resolution on: August 09, 2013, 07:09:38 pm
Be careful with hardware SPI - the max clock rate on the 3202 is 1.8MHz.

-j
13  Community / Bar Sport / Re: Are microwave oven food healthy? on: August 09, 2013, 08:06:06 am
Quote
I prefer organic veggies!

I prefer inorganic.  Carbon is bad for you.  100% of people who die have large quantities of carbon in their system.
14  Community / Bar Sport / Re: Are microwave oven food healthy? on: August 08, 2013, 06:48:01 am
Quote
When will people learn that the reason the cancer rate is going up is because our radiation rate is going up

It couldn't possibly be because the rate that other diseases are killing us is going down due to medical advances...


doh! I took the troll bait and actually responded!  bad geek, no shlashdot for you today...

15  Development / Other Hardware Development / Re: EAGLE- how to create another package based on existing one? on: August 07, 2013, 09:07:57 pm
Quote
So unless command line can do the copy, this is not working.

Sorry, should have said that was a command line (although the font was a hint).

If the source library is selected the copy command should find it.

-j
Pages: [1] 2 3 ... 169