ds28e17iic(4) - NetBSD Manual Pages

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DS28E17IIC(4)           NetBSD Kernel Interfaces Manual          DS28E17IIC(4)


NAME

     ds28e17iic -- Driver for Maxim DS28E17 1-Wire to I2C bridge


SYNOPSIS

     ds28e17iic* at onewire?


DESCRIPTION

     The ds28e17iic driver provides a 1-Wire to I2C bridge with a iic(4) bus
     at the far end using the DS28E17 bridge chip.

     The DS28E17 will automatically detect and deal with a end device that
     uses I2C clock stretching.


SYSCTL VARIABLES

     The following sysctl(3) variables are provided:

     hw.ds28e17iic0.readycount

     hw.ds28e17iic0.readydelay
             When the driver sends a transaction down the 1-Wire bus, these
             variables are how long to delay before reading the status on
             whether or not the conversion is done and the number of times to
             perform this read back.  In general, these values should be as
             short as possible, but if there are too short, a EAGAIN timeout
             will occur when the end device is just taking a longer than
             expect amount of time to respond.  This may be particularly
             noticed if end device is doing clock stretching.

     hw.ds28e17iic0.reportreadnostop
             If set to 1, report that an attempt to do a Read without a Stop
             occured.  The chip does not support that operation.  Read without
             Stop will be treated as a Read with a Stop with the hope that the
             end device will be able to deal with that.

     hw.ds28e17iic0.reportzerolen
             If set to 1, report that an attempt to perform a zero length read
             or zero length write occured.  The chip does not support zero
             length reads or writes.

     hw.ds28e17iic0.debug
             If the driver is compiled with DS28E17IIC_DEBUG, this node will
             appear and can be used to set the debugging level.


SEE ALSO

     onewire(4), iic(4), sysctl(8)


HISTORY

     The ds28e17iic driver first appeared in NetBSD 11.0.


AUTHORS

     The ds28e17iic driver was written by Brad Spencer
     <brad@anduin.eldar.org>.


BUGS

     While this may not be considered a bug, the DS28E17 chip will detach
     itself from the onewire(4) bus if there is not a device connected to its
     SDA and SCL pins.

     The i2cscan(8) command will not function entirely correctly when run
     against a DS28E17 chip.  The default mode of doing a I2C Write with Stop
     that is zero length is not supported by the DS28E17 chip.  When the
     i2cscan(8) command is used with its one byte read mode it will find
     devices as long as the device does not NACK on a I2C read.


NetBSD 10.99                   January 12, 2025                   NetBSD 10.99