Based on kernel version 6.8
. Page generated on 2024-03-11 21:26 EST
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 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. |