26 lines
1.0 KiB
Plaintext
26 lines
1.0 KiB
Plaintext
|
w1_ds2406 kernel driver
|
||
|
|
=======================
|
||
|
|
|
||
|
|
Supported chips:
|
||
|
|
* Maxim DS2406 (and other family 0x12) addressable switches
|
||
|
|
|
||
|
|
Author: Scott Alfter <scott@alfter.us>
|
||
|
|
|
||
|
|
Description
|
||
|
|
-----------
|
||
|
|
|
||
|
|
The w1_ds2406 driver allows connected devices to be switched on and off.
|
||
|
|
These chips also provide 128 bytes of OTP EPROM, but reading/writing it is
|
||
|
|
not supported. In TSOC-6 form, the DS2406 provides two switch outputs and
|
||
|
|
can be provided with power on a dedicated input. In TO-92 form, it provides
|
||
|
|
one output and uses parasitic power only.
|
||
|
|
|
||
|
|
The driver provides two sysfs files. state is readable; it gives the
|
||
|
|
current state of each switch, with PIO A in bit 0 and PIO B in bit 1. The
|
||
|
|
driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to
|
||
|
|
work with. output is writable; bits 0 and 1 control PIO A and B,
|
||
|
|
respectively. Bits 2-7 are ignored, so it's safe to write ASCII data.
|
||
|
|
|
||
|
|
CRCs are checked on read and write. Failed checks cause an I/O error to be
|
||
|
|
returned. On a failed write, the switch status is not changed.
|