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diff --git a/Documentation/w1/slaves/w1_ds2413.rst b/Documentation/w1/slaves/w1_ds2413.rst new file mode 100644 index 0000000000..c15bb5b919 --- /dev/null +++ b/Documentation/w1/slaves/w1_ds2413.rst @@ -0,0 +1,59 @@ +======================= +Kernel driver w1_ds2413 +======================= + +Supported chips: + + * Maxim DS2413 1-Wire Dual Channel Addressable Switch + +supported family codes: + + ================ ==== + W1_FAMILY_DS2413 0x3A + ================ ==== + +Author: Mariusz Bialonczyk <manio@skyboo.net> + +Description +----------- + +The DS2413 chip has two open-drain outputs (PIO A and PIO B). +Support is provided through the sysfs files "output" and "state". + +Reading state +------------- +The "state" file provides one-byte value which is in the same format as for +the chip PIO_ACCESS_READ command (refer the datasheet for details): + +======== ============================================================= +Bit 0: PIOA Pin State +Bit 1: PIOA Output Latch State +Bit 2: PIOB Pin State +Bit 3: PIOB Output Latch State +Bit 4-7: Complement of Bit 3 to Bit 0 (verified by the kernel module) +======== ============================================================= + +This file is readonly. + +Writing output +-------------- +You can set the PIO pins using the "output" file. +It is writable, you can write one-byte value to this sysfs file. +Similarly the byte format is the same as for the PIO_ACCESS_WRITE command: + +======== ====================================== +Bit 0: PIOA +Bit 1: PIOB +Bit 2-7: No matter (driver will set it to "1"s) +======== ====================================== + + +The chip has some kind of basic protection against transmission errors. +When reading the state, there is a four complement bits. +The driver is checking this complement, and when it is wrong then it is +returning I/O error. + +When writing output, the master must repeat the PIO Output Data byte in +its inverted form and it is waiting for a confirmation. +If the write is unsuccessful for three times, the write also returns +I/O error. |