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Commit de3d27fc authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab Committed by Dmitry Torokhov
Browse files

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: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
parent 730518f2

Documentation/input/walkera0701.txt

+35 −16
Original line number Diff line number Diff line 
===========================

Walkera WK-0701 transmitter

===========================



Walkera WK-0701 transmitter is supplied with a ready to fly Walkera

helicopters such as HM36, HM37, HM60. The walkera0701 module enables to use
@@ -10,7 +13,8 @@ or use cogito: 
cg-clone http://zub.fei.tuke.sk/GIT/walkera0701-joystick





Connecting to PC:

Connecting to PC

================



At back side of transmitter S-video connector can be found. Modulation

pulses from processor to HF part can be found at pin 2 of this connector,
@@ -19,7 +23,8 @@ modulation pulses to PC, signal pulses must be amplified. 


Cable: (walkera TX to parport)



Walkera WK-0701 TX S-VIDEO connector:

Walkera WK-0701 TX S-VIDEO connector::



 (back side of TX)

     __   __              S-video:                                  canon25

    /  |_|  \             pin 2 (signal)              NPN           parport
@@ -30,10 +35,10 @@ Walkera WK-0701 TX S-VIDEO connector: 
     -------        3 __________________________________|________________ 25 GND

                                                          E





I use green LED and BC109 NPN transistor.



Software:

Software

========



Build kernel with walkera0701 module. Module walkera0701 need exclusive

access to parport, modules like lp must be unloaded before loading
@@ -44,7 +49,8 @@ be changed by TX "joystick", check output from /proc/interrupts. Value for 






Technical details:

Technical details

=================



Driver use interrupt from parport ACK input bit to measure pulse length

using hrtimers.
@@ -53,17 +59,29 @@ Frame format: 
Based on walkera WK-0701 PCM Format description by Shaul Eizikovich.

(downloaded from http://www.smartpropoplus.com/Docs/Walkera_Wk-0701_PCM.pdf)



Signal pulses:

Signal pulses

-------------



::



                     (ANALOG)

      SYNC      BIN   OCT

    +---------+      +------+

    |         |      |      |

  --+         +------+      +---



Frame:

Frame

-----



::



 SYNC , BIN1, OCT1, BIN2, OCT2 ... BIN24, OCT24, BIN25, next frame SYNC ..



pulse length:

pulse length

------------



::



   Binary values:		Analog octal values:



   288 uS Binary 0		318 uS       000
@@ -80,7 +98,8 @@ pulse length: 
(Warning, pulses on ACK are inverted by transistor, irq is raised up on sync

to bin change or octal value to bin change).



Binary data representations:

Binary data representations

---------------------------



One binary and octal value can be grouped to nibble. 24 nibbles + one binary

values can be sampled between sync pulses.
@@ -100,10 +119,10 @@ binary value can be sampled. This bit and magic number is not used in 
software driver. Some details about this magic numbers can be found in

Walkera_Wk-0701_PCM.pdf.



Checksum calculation:

Checksum calculation

--------------------



Summary of octal values in nibbles must be same as octal value in checksum

nibble (only first 3 bits are used). Binary value for checksum nibble is

calculated by sum of binary values in checked nibbles + sum of octal values

in checked nibbles divided by 8. Only bit 0 of this sum is used.