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I want to use a USB mouse through a USB to PS/2 converter to interface to a microcontroller. Does the PS/2 protocol support scrolling wheel movement?

K_Trenholm
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Ganesh S
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1 Answers1

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The PS/2 interface does support wheel scrolling. If the mouse itself supports PS/2 interface (most USB mice still do, for use with passive adapters), and has a scroll wheel, then yes, scroll wheel support should be present through the converter. Mouse wheel data in the PS/2 protocol is sent in the 4th byte of data.

Byte 1: Flags and Button States

Byte 2: X Movement

Byte 3: Y Movement

Byte 4: Z Movement (Scroll Wheel)

Even then it only occupies the bottom 4 bits of the 4th byte (+7 to -7). The top 4 bits contain data for buttons 4 and 5 for Microsoft Intellimouse compatible devices.

More information on the PS/2 mouse protocol can be found Here.

K_Trenholm
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