1-wire and Dallas DS18b20

blink38

Hi,

I would like to interact with a therm device as Dallas DS18b20 using 1-wire interface. I am using raspbian for banana pi and there is only the 1-wire module (wire), not the w1-therm neither w1-gpio.

Will be these two module (w1-therm and w1-gpio) included in futur release of raspbian image for banana pi ? or where can I found the kernel header to be able to compile only these two module ?

Cordialy.

tony_zhang

The new image has include it, we will release it on later this month

blink38

It seems that wire, w1-therm and w1-gpio are not available on Raspbian 3. Am I right? must I wait for next release ?

Thanks

tony_zhang

I didn't test any w1 device. But I am sure that the w1 driver has ported into the kernel

zippetto

I've done several tests with a DS18B20 on 1-wire bus.

Last release of Raspbian modified for banana, kernel 3.4.90: unstable results;
Ubuntu core 14.04 with bananapi-bsp, kernel 3.4.90: unstable results;

For unstable results mean that sometimes w1_slave reads the value correctly, sometimes CRC error, sometimes the device disappears automagically.
I've used CON3-P07 and other pins for signal wire, changes to the fex but nothing.
I tried with other DS18B20 sensors, same results, while on the Raspberry board everything works perfectly.
Kernel module sunxi-w1 problem on A20?

pieter

Dear,

Am interested to see this work - with the new raspbian 3.1.  On a raspberry PI, it went OK, but still, cannot get it working on banana PI with raspbian 3.0:  in the /sys/bus... nothing appears and in dmesg I get the complaint that the GPIO's are malconfigured (after adding the extra section for w1).

Any help is welcome.

kind regards,
Pieter

pieter

Hello,

Got this working yesterday

connected pin 2 of the DS1820 to CON3 pin 16 (GPIO 4) of the BPI. (and a 4.7 KOhm resistor between pin 2 and 3 of the DS1820, connector between pin 1 and GND).

In software using the Raspbian V3.1, adapted script.bin with the sunxi tools:

[gpio_para]
...
gpio_pin_16 = portH01<1><default><default><default>
gpio_pin_23 = portH20<1><default><default><default>
...

[w1_para]
gpio = 23

put the new script.bin in place, reboot
and look at /sys/bus/w1 - :-)

enjoy,
Pieter

ucmaniac

Reply 7# pieter
With the official BananaPi kernel 3.4.90 1-wire only works as long as the CPU frequency is not dropping below approx. 500MHz. It seems, udelay is not properly scaled with CPU frequency. As a consequence the bus master misses the window when it should detect the slaves.
Test results for the 480us reset pulse (logic analyser):
1008MHz: 459us, 720MHz: 641us, 528us: 874us, 336MHz: 1372us (does not recognize slave)
This is clearly a bug in the kernel.
I have already a suspicion what the root cause for the strange udelay behaviour is, but I first need to check whether I am right.
Until the timing bug is resolved, keep the CPU frequency in the "safe" region.

tony_zhang

Reply 8# ucmaniac

Thanks for your mention. Could you check it from the source code on Github. https://github.com/LeMaker/linux-bananapi ?

FLED

Reply 8# ucmaniac

Thanks! Thanks! Thanks!

I already got crazy.... tried to control wireless outlets via 433MHz but it always failed.

Now it is clear... if the udelay doesn´t work properly it can´t work.

Hopefully this will be fixed in the next version