Device
General-purpose interface
Column
channels
Row
channels
Interrupt
generation
D
V
DD
Keyboard matrix
....
....
I/O
pads
L4
interconnect
gpif-003
Public Version
www.ti.com
General-Purpose Interface Environment
Figure 25-3. General-Purpose Interface Used as a Keyboard Interface
When a keyboard matrix key is pressed, the corresponding row and column lines are shorted together and
a low-level is driven on the corresponding row channel. This generates an interrupt based on the proper
configuration (see
, Interrupt and Wakeup).
When the keyboard interrupt is received, the processor (the MPU and/or IVA2.2 subsystem) can disable
the keyboard interrupt and scan the column channels for the key coordinates.
•
The scanning sequence has as many states as column channels: For each step in the sequence, the
processor drives one column channel low and the others high.
•
The processor reads the values of the row channels and thus detects which keys in the column are
pressed.
At the end of the scanning sequence, the processor establishes which keys are pressed. The keyboard
interface can then be reconfigured in the interrupt waiting state.
3467
SWPU177N – December 2009 – Revised November 2010
General-Purpose Interface
Copyright © 2009–2010, Texas Instruments Incorporated
Содержание OMAP36 Series
Страница 174: ...174 List of Tables SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 692: ...692 MPU Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 1084: ...1084 IVA2 2 Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 1990: ...1990 2D 3D Graphics Accelerator SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2334: ...2334 Memory Subsystem SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2700: ...2700 Memory Management Units SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2868: ...2868 HDQ 1 Wire SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 2974: ...2974 UART IrDA CIR SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3054: ...3054 Multichannel SPI SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3462: ...3462 MMC SD SDIO Card Interface SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3508: ...3508 General Purpose Interface SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3584: ...3584 Initialization SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...
Страница 3648: ...3648 Debug and Emulation SWPU177N December 2009 Revised November 2010 Copyright 2009 2010 Texas Instruments Incorporated ...