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by pgman
Sat Apr 06, 2013 7:16 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Help with RTC
Replies: 19
Views: 14158

Re: Help with RTC

@dhead - Ah, missed that point about the version nos. My problem seems to go well beyond boot up time though (up to 10 mins sometimes). I've disabled the dummy-RTC and the ntp access, so I know I've only got this one running. @spiro1 - simple question - have you set the clock at all? If the battery ...
by pgman
Sat Apr 06, 2013 1:59 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Help with RTC
Replies: 19
Views: 14158

Re: Help with RTC

I've got a board connected to the Pi with the resistors R2&R3 removed. It works most of the time, but I've had problems at start-up with it (RTC not ready). I think I may have an issue with the crystal though, as it drifts a lot more than it should. I'm running in another board on an Arduino (to est...
by pgman
Thu Apr 04, 2013 1:12 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

Re: RTC using P5 header

Try not to ignore the pull-up resistor issue. The ones on these board will pull the clock and data lines up to 5v. The GPIO pins are only meant to use 3.3v, so its important to remove any pull-up resistors that go to the 5v line, and instead connect new ones to the 3.3v supply (this isnt needed if u...
by pgman
Fri Mar 29, 2013 12:07 pm
Forum: General discussion
Topic: unable to stay log need to login very often
Replies: 5
Views: 949

Re: unable to stay log need to login very often

Same here. Had to log in 4 times just to write this post.

Everything was fine till today.
by pgman
Sun Mar 24, 2013 10:05 pm
Forum: General discussion
Topic: which GPIO addon card for RPI?
Replies: 8
Views: 1052

Re: which GPIO addon card for RPI?

50 DS18b20 chips can be bought from about £35 on ebay (china), but you'd have to encapsulate and waterproof them, unless you can reliably read the outside glass temp. There are also encapsulated ones at 10 for £17. These will be the most accurate and easiest electrically to set up - its a one wire b...
by pgman
Tue Mar 19, 2013 1:57 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C DVB-S2 tuner
Replies: 1
Views: 2123

Re: I2C DVB-S2 tuner

Assuming you mean to use these as satellite tuners for a Pi media centre, then not good. Firstly, you need to know what the control protocol is. Looking at the company web site there's precious little info on the DVB-S2 tuners, and what there is looks wrong (Input frequency range:48to860MHz - this s...
by pgman
Mon Mar 18, 2013 3:08 am
Forum: Camera board
Topic: Alternatives to the RasPi camera module
Replies: 10
Views: 6820

Re: Alternatives to the RasPi camera module

Search the web for QCUIAG - QuickCam and Unconventional Imaging Astronomy Group. They've been around for about 15 years and have been modifying webcams and other cameras to take long exposure pictures for astomony use. They've also got info on using unmodified cameras and video cameras to create lon...
by pgman
Sat Mar 09, 2013 3:42 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: DS18B20 Max Distance
Replies: 41
Views: 44253

Re: DS18B20 Max Distance

Are you running in 1-wire mode? According to the datasheet 1-wire mode, also called parasitic power mode, only needs ground and DQ with a pull-up resistor to +ve. In this mode the chip can pull as much as 1.5mA, so for 3.3v the resistor should be no greater than 2.2k for a single DS18b20. If you hav...
by pgman
Sun Mar 03, 2013 4:48 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: I2C interface on other pins...
Replies: 4
Views: 1522

Re: I2C interface on other pins...

How about using an Arduino Nano or atmega328 with bootloader connected via serial or SPI to the Pi. Then use the Arduino/atmega I2C bus to talk to the Lego. You can get an atmega328 kit with bootloader for less than £5/$8. All you would need to do then is write a bit of code on the arduino to talk t...
by pgman
Fri Mar 01, 2013 2:12 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: More than 17 relays via GPIO
Replies: 4
Views: 844

Re: More than 17 relays via GPIO

I'd go for I2C chips as well, something like the PCF8574 or the MCP23017. I've had issues with 74HC 595 and relays, causing random state changes whenever something touched the circuitry. Using I2C chips you will only get a state change when exactly the correct data stream is sent. You can buy them f...
by pgman
Sun Feb 24, 2013 2:11 pm
Forum: HATs and other add-ons
Topic: I2C clock and data pins
Replies: 7
Views: 6222

Re: I2C clock and data pins

There,s no shortage of info on setting up an RTC in the forums, there seems to be quite a few drivers already. What chip have you got?
by pgman
Sun Feb 24, 2013 2:30 am
Forum: HATs and other add-ons
Topic: I2C clock and data pins
Replies: 7
Views: 6222

Re: I2C clock and data pins

Hi Gert. Can you elaborate on the known bug in the BCM2835 I2C? I've been doing something with an I2C RTC board and get errors at boot time, that suddenly disapear after a few minutes. Up till now I've been assuming the RTC board has a fault, but if its down to a bug in the BCM2835 I2C, then I may a...
by pgman
Sun Feb 17, 2013 5:26 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

Re: RTC using P5 header

The pi already has 1k8 resistors to 3.3v on the I2C lines of the P1 header. Hence the reason for saying you need to remove R2 & R3 from this board. If you look in the original Adafruit tutorial it says that the 2k2 resistors should not be used. On the P5 header there are no pull-ups as the I2C is no...
by pgman
Sat Feb 16, 2013 1:38 am
Forum: Other projects
Topic: LCD display on really long wires
Replies: 1
Views: 706

Re: LCD display on really long wires

Wouldn't advise trying to directly connect to an LCD over more than about 50cm. What you are best off doing is using a serial to parallel converter chip and connecting that chip direct to the LCD. Have a look at this blog http://www.rpiblog.com/2012/07/interfacing-16x2-lcd-with-raspberry-pi.html It ...
by pgman
Tue Feb 05, 2013 10:47 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 74HC595 EMC(EMV) problems
Replies: 20
Views: 5914

Re: 74HC595 EMC(EMV) problems

I'm working on a similar project on the Arduino. In my case switching 16 relays (2 8way boards from China, with opto-isolation). I used 2 * 74HC595 with shared clock and data lines and one enable line per chip, plus a 3rd chip for a LCD display. Everything worked fine until I made contact with the r...
by pgman
Mon Jan 21, 2013 3:30 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

Re: RTC using P5 header

Yes, That is the module I've been using. The 2 resistors are the ones next to the ICs labelled R2 and R3. If you trace from the SDA/SCL pins you'll find a path to these 2 resistors. The other side is to the 5v pin. I can't find an actual schematic for this board though. I can read and set the clock,...
by pgman
Sat Jan 19, 2013 12:47 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: 5V i2c device problems
Replies: 8
Views: 3061

Re: 5V i2c device problems

Remove the pullup resistors on the 5v side, and ditch the convertors. I've used a 5v DS1307 clock just fine on 3.3v I2C rail. This was achieved by only having pullup resistors on the 3v3 side, ie the built in ones on the Raspberry. According to I2C specs the logic levels for 3v3 I2C are within the t...
by pgman
Wed Jan 09, 2013 9:00 pm
Forum: Graphics, sound and multimedia
Topic: BBC Radio-4-Matic
Replies: 18
Views: 14396

Re: BBC Radio-4-Matic

Location can be worked out from IP address. Do a search for "IP based Geo-Location". Seems accurate enough to get time-zone with a good degree of certainty.
by pgman
Tue Jan 08, 2013 4:22 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

Re: RTC using P5 header

Just to be clear in my prev post I meant to say RTC but spell checker changed it to etc.
by pgman
Tue Jan 08, 2013 4:19 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

Re: RTC using P5 header

Hi Peter247 I did start with the 5v pull up resistors removed and had 1k9 resistors pulling up to the 3v3 rail. I think I said that in the post originally. I've put using P5 on hold for now, and instead am using P1 in order to check the functioning of the board itself, and that threw up a whole host...
by pgman
Sun Jan 06, 2013 11:21 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

Re: RTC using P5 header

Cheers for the prompt reply. It makes sense that ALT0 functions need to be enabled. Just to satisfy myself that the hardware was OK I've connected the board to P1 pins 3&5. Et voila - it shows up in I2Cdetect -y 1 at address 68. Now according to the same wiki, these are GPIO02 and GPIO03, which have...
by pgman
Sun Jan 06, 2013 10:19 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: RTC using P5 header
Replies: 14
Views: 4174

RTC using P5 header

I'm trying to get a DS1307 RTC up and running on the new P5 header on a rev 2 board. According to posts about the rev 2 board, the P5 is meant to be used for things like 3rd party RTC boards. I've followed various tutorials on using I2C using 5v devices with the RPi. I've got the IC2 tools installed...

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