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3.18.3 HID

The reference design implements basic HID controls. The call to

vendor_ReadHidButtons()

simply reads from buttons A and B and returns their

state in the relevant bits depending on the desired functionality (play/pause/skip

etc). Note the buttons are active low, the HID controls active high. The buttons are

therefore read and then inverted.

/* Write HID Repor t Data into hidDat a array

* Bits are as follows :

* 0: Play / Pause

* 1: Scan Next Trac k

* 2: Scan Prev Trac k

* 3: Volume Up

* 4: Volime Down

* 5: Mute

void Ven d o r _Rea d H I DButt o n s ( unsigned char hidData [])

{

# ifndef MIDI

unsigned a , b ;

p_but_a :> a;

p_but_b :> b;

a = (~ a ) & 1;

b = (~ b ) & 1;

/* Assign buttons A and B to Vol Up / D own */

hidData [0] = ( a << 3) | ( b << 4);

# endif

}

In the example above the buttons are assigned to volume up/down.

3.18.4 Validated Build Options

The reference design can be built in several ways by changing the build options.

These are described in §5.1.

The design has only been fully validated against the build options as set in the

application as distributed. See §3.1 for details and binary naming.

In practise, due to the similarities between the U-Series and L-Series feature set, it

is fully expected that all listed U-Series conﬁgurations will operate as expected on

the L-Series and vice versa.

REV 6.1

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