weUSBscan.c File Reference

USB 1D / 2D scanners mimicking keyboards on Raspberry Pi. More...

#include "weUSBscan.h"

Variables
char const	deRawCoDisAltGrph [120]
	Key position number to character, AltGr, German keyboard. More...
char const	deRawCoDisNoShift [90]
	Key position number to character, no shift, German keyboard. More...
char const	deRawCoDisShifted [90]
	Key position number to character, shifted, German keyboard. More...
wchar_t	raw2wcharAltGrph [102]
	Key position number to character, with AltGR. More...
wchar_t	raw2wcharNoShift [60]
	Key position number to character, no shift. More...
wchar_t	raw2wcharShifted [60]
	Key position number to character, with shift. More...
unsigned char	scanKeyAction [32]
	The one keystroke read buffer. More...
int	scanKeybLang
	The keyboard language. More...
wchar_t	scanResult [162]
	The result of one scan. More...
char const	usRawCoDisNoShift [90]
	Key position number to character, no shift, US keyboard. More...
char const	usRawCoDisShifted [90]
	Key position number to character, shifted, US keyboard. More...

Detailed Description

USB 1D / 2D scanners mimicking keyboards on Raspberry Pi.

Copyright  (c)   2020     Albrecht Weinert
weinert-automation.de     a-weinert.de
 
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Revision history

Rev. 234 20.01.2021
Rev. 232 03.09.2020 : new (extracted from testOnPi.c)

This is a supplementary basic library to handle USB barcode and QR code scanners. By plug'n play such scanner would normally appear as device

/dev/hidraw0  

. To make this usable for scanner application programs run without sudo apply

sudo chmod  664 /dev/hidraw0  

before.

Variable Documentation

usRawCoDisNoShift

char const usRawCoDisNoShift[90]

Key position number to character, no shift, US keyboard.

This utf-8 or multibyte character array respectively string describes the translation of key number to character for a US keyboard.
It will have to be transfered as wide character array to raw2wcharNoShift.

usRawCoDisShifted

char const usRawCoDisShifted[90]

Key position number to character, shifted, US keyboard.

See the explanation at usRawCoDisNoShift.

See also

raw2wcharShifted

deRawCoDisNoShift

char const deRawCoDisNoShift[90]

Key position number to character, no shift, German keyboard.

This utf-8 or multibyte character array respectively string describes the translation of key number to character for a US keyboard.
It will have to be transfered as wide character array to raw2wcharNoShift.

Remarks on non US keyboard emulations by the "USB Wired 2D Barcode Scanner" <MJ-8200> and consorts:
We strongly recommend not to use them and refrain from applications using more than primitive USASCII. As "German keyboard", e.g., the scanner does neither recognise nor send ÇÏÇôǬÇ?Ç?Ç?Ç?. Besides being called German without umlauts [sic!] the scanner is ignorant to some other characters on every German keyboard (which are probably there because of being used in Western Europe). Additionally the scanner when set to German inserts additional strings of characters with no obvious sense or system.
In the end we consider everything beyond factory reset (except low beeper volume) as not functional.
Without the hard bug of inventing characters and string not contained in the QR-code, the so called German keyboard would give us some extra characters — but not umlauts.

deRawCoDisShifted

char const deRawCoDisShifted[90]

Key position number to character, shifted, German keyboard.

See the explanation at usRawCoDisNoShift.

See also

raw2wcharShifted deRawCoDisNoShift

deRawCoDisAltGrph

char const deRawCoDisAltGrph[120]

Key position number to character, AltGr, German keyboard.

See the explanation at usRawCoDisNoShift.

See also

raw2wcharShifted deRawCoDisNoShift

raw2wcharNoShift

wchar_t raw2wcharNoShift[60]

Key position number to character, no shift.

The length is 60. Valid characters are in the 4..56 key number range; there may be gaps. 0..3 are errors.

See also

usRawCoDisNoShift

raw2wcharShifted

wchar_t raw2wcharShifted[60]

Key position number to character, with shift.

The length is 60. Valid characters are in the 4..56 key number range; there may be gaps. 0..3 are errors.

See also

usRawCoDisShifted

raw2wcharAltGrph

wchar_t raw2wcharAltGrph[102]

Key position number to character, with AltGR.

The length is 60. Valid characters are in the 4..56 key number range; there will be many gaps. 0..3 are errors.

See also

usRawCoDisShifted

scanKeybLang

int scanKeybLang

The keyboard language.

The language of the USB keyboard (see scanKeyAction) emulated by the scanner is stored here as: 0=US (default), 10=DE

scanResult

wchar_t scanResult[162]

The result of one scan.

The result of consecutive keystrokes (see scanKeyAction) is stored here as array respectively string of wide characters.

scanKeyAction

unsigned char scanKeyAction[32]

The one keystroke read buffer.

Keyboard input comes in blocks of 8 bytes each. Hence a length of 8 would be sufficient. Hence, 32 is a reserve for device errors or the driver not recognising the gap between blocks.

The 8 bytes are:

              Bit/Value:  0/1 1/2   2/4 3/8         4/16 5/32  6/64  7/128
[0]  Modifier keys Left: cntl shift Alt Win  Right: cntl shift AltGr Win
[1]  Reserved field                  always 0
[2]  Keypress 1                      in a funny code (4 is a)
[3]  2nd simultaneously pressed key
[4..7]  Keypress 3..6

As scanners won't "press" more than one key at a time only bytes [0] and [1] will contain information.
Byte[2] will be a crazy key code for a..z1..90... athwart to any utf or unicode. In the end the semantic of that "code" is a mixture of key value and key position on the keyboard. In the end few scanners get more than an American (and a Chinese?) keybord right. When setting the scanner to German keyboard you may miss one or two of ÇÏ Çô Ǭ Ç? Ç? Ç? Ç?.

On byte [0] one should see only three values: /code 0 : no modifier, no shift 2 : shift, that means a->A 64: altGr