Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
Input: walkera0701 - convert documentation into ReST format
This file require minimum adjustments to be a valid ReST file.
Do it, in order to be able to parse it with Sphinx.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
authored by
Mauro Carvalho Chehab
and committed by
Dmitry Torokhov
de3d27fc
730518f2
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Documentation/input/walkera0701.txt
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Documentation/input/walkera0701.txt
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===========================
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Walkera WK-0701 transmitter
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===========================
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Walkera WK-0701 transmitter is supplied with a ready to fly Walkera
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helicopters such as HM36, HM37, HM60. The walkera0701 module enables to use
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cg-clone http://zub.fei.tuke.sk/GIT/walkera0701-joystick
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Connecting to PC:
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Connecting to PC
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================
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At back side of transmitter S-video connector can be found. Modulation
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pulses from processor to HF part can be found at pin 2 of this connector,
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Cable: (walkera TX to parport)
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Walkera WK-0701 TX S-VIDEO connector:
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Walkera WK-0701 TX S-VIDEO connector::
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(back side of TX)
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__ __ S-video: canon25
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/ |_| \ pin 2 (signal) NPN parport
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------- 3 __________________________________|________________ 25 GND
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E
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I use green LED and BC109 NPN transistor.
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Software:
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Software
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========
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Build kernel with walkera0701 module. Module walkera0701 need exclusive
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access to parport, modules like lp must be unloaded before loading
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Technical details:
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Technical details
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=================
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Driver use interrupt from parport ACK input bit to measure pulse length
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using hrtimers.
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Based on walkera WK-0701 PCM Format description by Shaul Eizikovich.
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(downloaded from http://www.smartpropoplus.com/Docs/Walkera_Wk-0701_PCM.pdf)
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Signal pulses:
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(ANALOG)
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SYNC BIN OCT
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+---------+ +------+
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| | | |
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--+ +------+ +---
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Signal pulses
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-------------
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Frame:
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::
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(ANALOG)
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SYNC BIN OCT
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+---------+ +------+
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| | | |
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--+ +------+ +---
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Frame
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-----
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::
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SYNC , BIN1, OCT1, BIN2, OCT2 ... BIN24, OCT24, BIN25, next frame SYNC ..
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pulse length:
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pulse length
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------------
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::
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Binary values: Analog octal values:
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288 uS Binary 0 318 uS 000
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(Warning, pulses on ACK are inverted by transistor, irq is raised up on sync
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to bin change or octal value to bin change).
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Binary data representations:
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Binary data representations
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---------------------------
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One binary and octal value can be grouped to nibble. 24 nibbles + one binary
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values can be sampled between sync pulses.
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software driver. Some details about this magic numbers can be found in
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Walkera_Wk-0701_PCM.pdf.
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Checksum calculation:
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Checksum calculation
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--------------------
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Summary of octal values in nibbles must be same as octal value in checksum
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nibble (only first 3 bits are used). Binary value for checksum nibble is
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calculated by sum of binary values in checked nibbles + sum of octal values
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in checked nibbles divided by 8. Only bit 0 of this sum is used.
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