44-Pin Qfp Mc68Hc908Jb8 Features; Hardware Descriptions - Motorola M68HC08 Designer Reference Manual

USB and PS/2 Multimedia Keyboard Interface

1.3 44-pin QFP MC68HC908JB8 Features

1.4 Hardware Descriptions

Designer Reference Manual
8
Freescale Semiconductor, Inc.
The 44-pin QFP MC68HC908JB8 is targeted for USB and PS/2 interface
keyboard applications with minimum external components needed.
Features include:
• USB D+ and D– pins shared with PS/2 data and clock pins
• 27 out of 37 I/O pins with internal pull-up supports up to 8x19 key
matrix
• 10mA direct drive pins for the Num Lock, Caps Lock and Scroll
Lock LEDs
• Internal 1.5K pull-up for USB D– data line
• Internal 5K pull-ups for PS/2 data and clock pins
Scroll LED
Caps LED
Num LED
8 x 18
Key Matrix
USB to PS/2
USB Plug
Converter
Figure 1-2. USB and PS/2 Connections
USB and PS/2 Multimedia Keyboard Interface
For More Information On This Product,
Go to: www.freescale.com
MC68HC908JB8
Figure 1-1. Block Diagram
6
5
3
1 2
PS/2 Plug
USB Plug
6-pin PS/2 Plug
1 – Data (USB D– pin)
2 – NC
4
3 – Ground (USB Ground)
4 – + 5V (USB +5V)
5 – Clock (USB D + pin)
6 – NC
DRM014 — Rev 0
MOTOROLA