Hi has anyone successfully connect a 1wire device that uses the DS28E17 to the 1 wire pi ?

Hi

We have not tested the DS28E17 on the 1 Wire Pi. In theory, it should be compatible with the DS2482-100 1-Wire controller used on the 1 Wire Pi but the problem you will have is finding software drivers to communicate between the DS2482-100 and the DS28E17.

The DS28E17 is not listed as a compatible device on the OWFS website so you will not be able to use OWFS to talk to the device. You may have to write a custom Linux kernel driver to make the DS28E17 appear as an I2C bus within Linux. I don't have any experience with writing kernel drivers so this is not something I could help you with.

The DS28E17 is supported by the kernel although that's for the gpio 1wire do you know if the existing kernel drivers can use this hardware instead of gpio ?

If you enable the DS2482 kernel module to work with the "w1" subsystem using the steps below you should be able to use the w1_ds28e17 kernel driver.

sudo modprobe ds2482
sudo sh -c "echo ds2482 0x18 > /sys/bus/i2c/devices/i2c-1/new_device"
sudo modprobe wire

Any 1-wire devices connected to the 1 Wire Pi will be available in the /sys/bus/w1/devices directory.

The GitHub repository for the w1_ds28e17 driver has more information on getting it working. It does say that the w1_ds28e17 driver is compatible with the DS2482 so it should work with the 1 Wire Pi but as I have not tested it myself I can not give you any guarantees that it will be compatible.

One issue you will find is the DS28E17 only works at 3.3V and the 1 Wire Pi is designed to work at 5V. You can change the 1 Wire Pi to work at 3.3V by removing the jumper J1 on the 1 Wire Pi Plus or the POWER solder bridge on 1 Wire Pi Zero to isolate it from the 5V supply and connect a wire between the 3.3V pin on the Raspberry Pi GPIO header and the 5V pin next to the RJ12 connector on the 1 Wire Pi. The photo below shows where the wire needs to connect. This should convert the 1 Wire bus to 3.3V making it compatible with the DS28E17.

Be careful not to accidentally short the jumper pins once you have connected the 3.3V to the 1 Wire Pi as this will feed 5 volts directly into the 3.3V pin on the GPIO header and damage the Raspberry Pi.



If you need to use other 5V 1 Wire devices on the same bus as the DS28E17 there is a circuit in section "2.3 Interfacing the DS28E17 with a 5V 1-wire bus and/or 5V I2C device" of the w1_ds28e17 GitHub repository which will level shift the 5V bus to 3.3V.