Raspberry Pi Forums

repton

My first thought is "how much power does it waste when nothing is plugged in?" I like to be able to turn things off when they're not being used...

Paul

repton

I've now got some 2x20 headers in stock and a batch of the PCBs made and these are now on sale:

http://www.sheepwalkelectronics.co.uk/p ... ucts_id=67

As you can see from the below photos they fit perfectly on both the A+ and B+.

: RPI3v2-Amed.jpg (47.79 KiB) Viewed 3174 times

: RPI3v2-Bmed.jpg (44.77 KiB) Viewed 3174 times

Paul

repton

AndrewS wrote:Apologies for the "intrusion".

No apology needed, I'm always up for constructive suggestions

Paul

repton

However in that case, why are you using a USB A socket (which is used by host devices, i.e. the ones normally supplying the power) rather than a USB B socket (which is used by slave devices, i.e. the ones normally consuming the power) :?: No reason really other than I guess that I happened to have ...

repton

I've just built up the first of the PCBs for my 8 Channel 1-Wire Master for the B+. It's electrically identical to my existing RPI3 board with physical changes to fit the B+ format. Please forgive the 26way GPIO connector as I don't have any 40way ones yet.

Paul

repton

I got one from Farnell.

Just need to redesign the PCBs for the expansion boards I make to suit it now...

Paul

repton

I have a Banana Pi (so they definitely do exist) and for what it's worth they are very definitely NOT 100% physically compatible with a Raspberry Pi. I've not got as far as plugging it in yet as I'm waiting for an SD card to arrive so I can't comment on if it actually works or not. For a start the b...

repton

I would say it is almost certainly your wiring. Replace all the cables with a twisted pair cable (i.e. cat5/cat6) and it should work.

You should not need a resistor anywhere on the network with the host adapter you're using.

Paul

repton

rmp wrote:Take a look at this project for example : http://raspberrypi.homelabs.org.uk/i2c- ... e-masters/

We are selling DS2482-x00 based masters for the RasPi.

See http://www.sheepwalkelectronics.co.uk/RPI2.shtml and http://www.sheepwalkelectronics.co.uk/RPI3.shtml for more information.

Paul

repton

paddyjoy wrote:I managed to get this working reliably tonight by using a 1K pull up resistor

Well that's me having learnt something today then, I wouldn't have expected that to work!

Paul

repton

I have also learned that the star configuration is the worst topology to use and that I probably should have put the data and gnd in the same twisted pair. Does anyone have any what I can do other than rewiring the network, which will take me 2 days :-( As you've already worked out the issue is tha...

repton

This sounds to me like a perfect application for a 1-Wire network. You are probably looking at a bigger network that you could reliably work with the kernel based driver but with a DS9490R USB host adapter or an I2C based host adapter such as my RPI2 (http://www.sheepwalkelectronics.co.uk/RPI2.shtml...

repton

Oddly enough I’m in the middle of creating a pcb add on board for the pi to provide 1-wire support over RJ45. Like this: http://www.sheepwalkelectronics.co.uk/RPI1.shtml or this: http://www.sheepwalkelectronics.co.uk/RPI2.shtml The first one connects to GPIO4 to use the kernel 1-Wire driver, the se...

repton

- can a sensor (on stubbed topology) be on a cable (Currently, I have a sensor on 1m cable) or should be only sensor connected directly on bus cable? You can have stubs but the shorter the better. Maxim's own guides suggest a maximum of 3m but if you have a big network keeping them much shorter tha...

repton

Additional info: * 7 x DS18B20 cables are different length (min: 5m, max: 12m). I don't know if it's just the way you worded it but from that it sounds like you have each sensor wired individually back to your Pi in a star topology. It might well not be the cause of your problems but you should bea...

repton

No it won't work, the main difference between the B and the A is that the USB hub IC is missing off the model A so those pins aren't connected to anything. If you want two USB ports get a model B.

Paul

repton

Are there actually other One-Wire sensors that are supported by Linux? E.g. a humidity sensor, etc? Almost every 1-Wire device is supported by Linux given the right software. I think the kernel 1-Wire driver is a little limited as to what it supports but if you're using a USB or I2C connected maste...

repton

saltydog wrote:
Code: Select all
sudo nano /etc/modules
Then adding:
Code: Select all
w1-gpio
w1-therm

This is what I would consider the "correct" way of doing it although all the other options mentioned in this thread should also work.

Paul

repton

Has anyone managed to get the DS18B20 sensor working on a pin other than GPIO4? Not directly, no. The kernel 1-Wire driver is hard coded to GPIO4 so it won't work on any other. If you want a 1-Wire sensor without using GPIO4 you will need to use a hardware based master such as a USB connected DS949...

repton

fcara wrote:DS18b20 sensors are connected to +5v and ground and their data lines have been pulled-up with 3 resistors (4.7kohm) .

If you're using a DS2482 as your bus master then you don't need any pull up resistors on the data lines, it's only if you're using the kernel/GPIO driver that you need those.

Paul

repton

I dont see why you are trying to do something un-necessary I don't think it is unnecessary. The OP's point is that with many people offering add-on boards that sit over the I2C pins on the GPIO connector and given the very nature of I2C that multiple devices can be connected to the bus we could do ...

repton

Either option 1 or 2 should work fine, I would recommend against 3 as it is unlikely to be able to supply enough power.

HTH,
Paul

repton

dm314 wrote:Btw, why did the tutorial added just only "rtc-1307" to /etc/modules instead of "rtc-ds1307"?
Just curious, but rtc-1307 worked for me when I didn't have my current problem.

I suspect that is simply a bug in the tutorial as the module on mine seems to be rtc-ds1307 too.

Paul

repton

The reason I ask is that i tried to do it that way but because WPA_Supplicant is preinstalled, if I changed the wlan0 to static it wouldn't do anything because it still wanted to get the settings from wpa_supplicant,conf. Unless you also removed the line wpa-roam /etc/wpa_supplicant/wpa_supplicant....

repton

what version of debian are you using? It's whatever the latest Raspbian was about 2 or 3 weeks ago. The file I used to make the SD card is "2012-12-16-wheezy-raspbian.img". The other thing with doing it that way is that you'd have to reconfigure the /etc/network/interfaces file every time you used ...

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