One Wire interface and Display issue

[cameron.devine]

I am working on a project where both the Raspberry Pi touchscreen, and several DS18B20 One Wire temperature sensors are used. I have gotten both of these parts working separately, but have not been able to get them to work together.

With the Device Tree off I am able to use the DS18B20 temperature sensors, but the touch functionality of the touchscreen is missing. When the Device Tree is on I am able to use the Touchscreen, but the DS18B20 isn't working.

I tried moving the temperature sensor to a different pin with the Device Tree off, but that didn't help.

Is there a way to get either the touch functionality of the touchscreen working without the Device Tree, or the One Wire interface working with the Device Tree on?

Any help on this issue would be greatly appreciated.

Cameron Devine

[rpdom]

Have you tried using the correct device tree line to activate the one-wire interface?

I haven't got a touch screen, but all my DS18B20s work using device tree.

[cameron.devine]

That was the issue. I had dtoverlay=1w-gpio not dtoverlay=w1-gpio.

Thank you for your help.

Cameron

[joeacamb]

Hi Cameron,

I am working in a project quite similar to yours. I have a 8 Temperature sensor system working 100% OK. Lately I've adquired a touchscreen and now I want to work with them together. The touchscreen is a JOY-IT with Item number = RB-TFT3.2-V2 and the Temperature sensors are Dallas 18B20P (ones that work in parasite mode). The main problem is that my touchscreen is making use of the first 26 Raspberry's Pins therefore taking all power PINS and also the w1-gpio PIN that is number 4. I've tried to change the w1-gpio PIN but without success. I've tried everything I've found in forums, for instance:

-Add to the /boot/config.txt the dtoverlay=w1-gpio,gpio=XX line
-Add to the /boot/cmdline.txt the bcm2708.w1_gpio_pin=XX ( with XX =16 in my case)

Anyways if I could be able to change the w1-gpio PIN I have no power PIN to work with. I've attended to make some parallel connections but afterwards it seems to be that I cannot get the enough current to work with the Touchscreen and the sensors.

If you have already solved your problem I'd be very thankful if you could give me some advices.

Thanks in advanced,

[texy]

Hi Cameron,

I am working in a project quite similar to yours. I have a 8 Temperature sensor system working 100% OK. Lately I've adquired a touchscreen and now I want to work with them together. The touchscreen is a JOY-IT with Item number = RB-TFT3.2-V2 and the Temperature sensors are Dallas 18B20P (ones that work in parasite mode). The main problem is that my touchscreen is making use of the first 26 Raspberry's Pins therefore taking all power PINS and also the w1-gpio PIN that is number 4. I've tried to change the w1-gpio PIN but without success. I've tried everything I've found in forums, for instance:

-Add to the /boot/config.txt the dtoverlay=w1-gpio,gpio=XX line
-Add to the /boot/cmdline.txt the bcm2708.w1_gpio_pin=XX ( with XX =16 in my case)

Anyways if I could be able to change the w1-gpio PIN I have no power PIN to work with. I've attended to make some parallel connections but afterwards it seems to be that I cannot get the enough current to work with the Touchscreen and the sensors.

If you have already solved your problem I'd be very thankful if you could give me some advices.

Thanks in advanced,

Hi and welcome to the forum.
I would ditch that display and choose another - one that has a GPIO 'pass-through' connector. Although your display has a 26-way connector, it probably isn't using all of those pins. Most GPIO based display boards use the SPI bus plus 2 or 3 other general GPIO lines.
Texy