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by kaos
Tue Aug 21, 2012 12:55 pm
Forum: HATs and other add-ons
Topic: RFID Chip Interface
Replies: 1
Views: 1289

Re: RFID Chip Interface

Almost. The CR003 is a 5V device, while the Raspi is 3.3V, so you will need a level shifter. Search the forum for those; there are several different types you could use, and I think all of them have been discussed here ;) .

--
Best regards, Kári.
by kaos
Mon Aug 20, 2012 9:55 pm
Forum: HATs and other add-ons
Topic: Keypad interface with ADP5589
Replies: 2
Views: 1850

Re: Keypad interface with ADP5589

If you have the pins to spare, you can set 16 buttons up in a 4x4 matrix (see http://www.dribin.org/dave/keyboard/one_html/ ) and read them with 8 lines of standard GPIO; no additional components needed! Indeed, you can get away with 5 lines by using charlieplexing (see http://en.wikipedia.org/wiki/...
by kaos
Mon Aug 20, 2012 12:59 pm
Forum: HATs and other add-ons
Topic: Is a Gertboard needed?
Replies: 8
Views: 2893

Re: Is a Gertboard needed?

Depends somewhat on what kind of motor you mean. I have been doing some experiments with a cheap hobby model servo motor. It can be controlled by direct connection to the PWM pin on the Raspi's GPIO connector; mind you, it does need a separate power supply. Mahjongg is right though, when he says tha...
by kaos
Sun Aug 19, 2012 10:53 am
Forum: HATs and other add-ons
Topic: RS232 Thermal Printer
Replies: 10
Views: 7492

Re: RS232 Thermal Printer

At the very least you will need a level converter. The Raspi has a UART available on the GPIO connector, but it is 3.3V logic level, while the printer is full-spec RS232 with up to +/-12V signalling. Others have recommended the MAX3232 chip for this. That still leaves a flow control problem. The Ras...
by kaos
Sun Aug 19, 2012 10:32 am
Forum: Camera board
Topic: USB Camera Dongle - compatible model?
Replies: 6
Views: 9116

Re: USB Camera Dongle - compatible model?

I am currently fooling around with a Logitech C170 webcam. Cost ca. 3000 ISKR = ca. 15 UKP, but that is with our insane VAT; I would expect to see it for around 10 UKP in Britain. It was automatically detected (under Raspbian) as a UVC device, and seems to work fine connected directly to the Raspi (...
by kaos
Thu Aug 16, 2012 2:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Interfacing with a board from different supply
Replies: 2
Views: 691

Re: Interfacing with a board from different supply

3.3V is the same voltage as the Raspi uses on it's GPIO pins, so should work perfectly. Yes, you have to tie the ground rails together to get them to communicate. This should preferably be done at a single point to avoid ground loops, but as long as your project fits in a single room, these should n...
by kaos
Sun Aug 12, 2012 2:23 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 16 x 2 LCD case screen
Replies: 18
Views: 15442

Re: 16 x 2 LCD case screen

Farnell, and also RS I presume, carry a selection of these displays. You can find Farnell's search engine at http://export.farnell.com/displays-lcd_alphanumeric . A few points to consider when selecting these displays: 1) Serial vs. parallel. Parallel is much more common, but serial displays also ex...
by kaos
Sat Aug 11, 2012 11:26 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: How to set PWM period
Replies: 2
Views: 1337

Re: How to set PWM period

Thanks. I've managed to do just that now. I was a bit apprehensive about messing with somebody else's source, but it was less painful than I anticipated ;)

--
Best regards,
Kári.
by kaos
Tue Aug 07, 2012 1:22 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: How to set PWM period
Replies: 2
Views: 1337

How to set PWM period

I want to use the GPIO PWM pin to control a servo. I have found Gordon's WiringPi library, which has a pwmWrite function that I guess controls the pulse/pause ratio, but I don't know what the total period or frequency of the PWM output is, or how to set it. AIU, a standard servo requires a PWM frequ...
by kaos
Thu Jul 12, 2012 10:20 pm
Forum: General discussion
Topic: Accessories
Replies: 19
Views: 2368

Re: Accessories

1) Yes, a simple RCA - RCA cable is enough, provided that your TV has an RCA video in socket. Mind you, the resolution you get that way is limited, and if you are using an old fashioned CRT TV, the flickering is v. annoying. I recommend a HDMI or DVI monitor if you have the option. 2) Not necessaril...
by kaos
Wed Jul 11, 2012 9:31 am
Forum: Beginners
Topic: 5V Regulator (battery powered)
Replies: 5
Views: 1749

Re: 5V Regulator (battery powered)

@ dj-party: Yes, if it does what it says on the label, it should work. I assume the access-point takes 5V and non-ridiculous amount of current? Though, with 10A to play with, current really shouldn't be an issue. @ Super-Nathan: I wouldn't recommend the LM340, or any other linear regulator for that ...
by kaos
Tue Jul 10, 2012 10:50 pm
Forum: Beginners
Topic: Power restriction in Quick Start guide
Replies: 3
Views: 669

Re: Power restriction in Quick Start guide

Standard USB ports only deliver max 500mA of current, and then only after negotiation with the connected device, which Raspi doesn't do, while Raspi requires 700mA. Lately some computers have come out with special "charging" ports that can deliver more current, intended to charge mobile phones and t...
by kaos
Mon Jul 09, 2012 11:09 pm
Forum: Beginners
Topic: Wireless options
Replies: 1
Views: 1046

Re: Wireless options

If you intend to continue using the Netgear router as your main router/access point, it is the Airport router you need to reconfigure. I'm afraid I know nothing about that router, but almost all routers I have come across (excepting some crippleware ISP provided ones) are capable of acting as a clie...
by kaos
Mon Jul 09, 2012 1:19 pm
Forum: Beginners
Topic: Recommended power supplies
Replies: 4
Views: 2025

Re: Recommended power supplies

@ grim2020: If your powersupply does what it says, it should work with no problems, though I don't know what they mean by "TTL loading". The simplest test you can do requires a voltmeter or multimeter. Touch TP1 on the RASPI with the positive probe and TP2 with the negative probe. You should get a r...
by kaos
Sun Jul 08, 2012 12:58 pm
Forum: Other projects
Topic: North American Power Supply
Replies: 1
Views: 816

Re: North American Power Supply

First of all, it's a micro -USB connector. Mini-USB also exists, but won't fit. As for the pinout, Google is your friend, as is Wikipedia :-) http://en.wikipedia.org/wiki/Universal_Serial_Bus Scroll down to the "Physical appearance" section. You only need to connect the +5V and ground lines. Mind yo...
by kaos
Sun Jul 01, 2012 11:39 am
Forum: Beginners
Topic: power supply question
Replies: 2
Views: 690

Re: power supply question

It should be safe to use. Where did you get the max 1200mA figure? I know that at least some versions of the quick start guide included with the Raspi had a misleading statement to the effect that the max current should be 700mA. I think the misunderstanding comes from the fact that the mA figure pr...
by kaos
Wed Jun 13, 2012 8:39 pm
Forum: Other projects
Topic: Case alternative in the works
Replies: 27
Views: 7430

Re: Case alternative in the works

Very interesting. One suggestion: Maybe add a ledge or shelf underneath the SD card. This could both give support to the card in case it receives a knock, serve as guide for easier card insertion, and also add strength to what looks like the weakest point of the frame. +1 for the idea of an optional...
by kaos
Tue Jun 12, 2012 10:21 pm
Forum: Other projects
Topic: A Raspi disclosure
Replies: 1
Views: 1442

A Raspi disclosure

No, not the GPU programming interface. Rather, the opposite of en closure: 0198-0019 12-06-2012 18-57.thumb (Medium).jpg I decided I wanted to keep my Raspi easily accessible for various probing and prodding, but at the same time I wanted to keep it safe from accidental screwdrivers and generally ra...
by kaos
Mon Jun 11, 2012 11:29 pm
Forum: Beginners
Topic: Operating System
Replies: 3
Views: 914

Re: Operating System

AIUI, yes and no. You will always need an SD card with a boot partition, as the Raspi is hardwired to start the bootloader from there. You can, however, place the actual OS filesystem on a USB device. Note that I'm no expert, and hopefully someone will come along to either confirm or correct, but th...
by kaos
Fri Jun 08, 2012 9:51 pm
Forum: Beginners
Topic: RCA TV hurts eyes
Replies: 6
Views: 11396

Re: RCA TV hurts eyes

I feel your pain. :( I've been using the same setup for the few days since I got my Raspi, since I forgot to order a HDMI/DVI cable. Trouble is, composite video (i.e. analogue TV signal) just isn't very good for high resolution computer displays. Not only is the resolution limited and fixed, but eve...
by kaos
Wed Jun 06, 2012 10:14 pm
Forum: Beginners
Topic: Setting password policy (Debian)
Replies: 2
Views: 6363

Re: Setting password policy (Debian)

That worked!
Thank you very much.

--
Kári.
by kaos
Wed Jun 06, 2012 9:27 pm
Forum: Beginners
Topic: Setting password policy (Debian)
Replies: 2
Views: 6363

Setting password policy (Debian)

How do you relax the default password policy under Debian somewhat? I just activated SSH, and thought I had better change the default password. A little bit of googling told me that this could be done with the passwd command (can you tell I'm a Linux newbie :D ). Unfortunately all my passwords were ...
by kaos
Sun Jun 03, 2012 11:24 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C ADC
Replies: 99
Views: 29648

Re: I2C ADC

Firstly, for the analogue inputs on pins 1 to 8 the datasheet recommends using a 1uF bypass cap (which I've added on my diagram, is that correct with them tied between the input and ground like that? Secondly, given that the values I'm using are going to be changing very slowly... glacially slow in...
by kaos
Sun Jun 03, 2012 10:46 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: CAN controller
Replies: 814
Views: 343361

Re: CAN controller

See older thread on CANbus here: http://www.raspberrypi.org/phpBB3/viewtopic.php?f=41&t=2298&hilit=canbus Zorce, ..... But I still need to read up in the thread above about whether the level conversion is necessary or not. Depending on the outcome I may order one. I looked up the schematic and the ...
by kaos
Tue May 29, 2012 8:30 am
Forum: Other projects
Topic: Portable TV, 3.5mm AV in
Replies: 3
Views: 2374

Re: Portable TV, 3.5mm AV in

If it really is A /V, that is both audio and video, it will require a 4 conductor plug, not a 2 conductor mono one. These are fairly common, but unfortunately the pinout isn't standardized; this guy has listed some variations: http://anythingbutipod.com/2006/04/zen-vision-m-video-cable-other-4pole-3...

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