Electronic Interface Between Baseband And Keypad - Nokia 301 Service Manual

RM-839; RM-840; RM-841
System Module
• Hardware acceleration for standard and antialiased bitmap fonts (color expansion)
• Hardware acceleration for image processing (rotation/mirroring, resize and bilinear up/downscaling)
• Hardware acceleration for YCbCr 4:4:4/4:2:2/4:2:0 to RGB conversion
• Hardware acceleration for overlay with alpha blending/chromakeying
• Hardware acceleration for directed or periodic display update (full or partial)
• Supported framebuffer cache formats: ARGB4444, ARGB1555, ARGB8888, RGB565
Figure 48 LCD interface

Electronic interface between Baseband and keypad

The Keypad Interface is a peripheral controller, which can be used for scanning external keypad matrices
with up to 8 rows and 8 columns (that is 64 standard keys). By adding an additional row of keys connected
to ground the number of keys can be extended by up to 8 keys. This results in a maximum number of 72 keys
to by identified by the Keypad Interface Controller.
The Keypad Scan Module reduces the number of interrupts and polling through the processor and therefore
reduces the power consumption. The module is able to debounce and scan the external keypad matrix
automatically without any software intervention. After debouncing it generates an interrupt. The interface
controller contains information about the key (or key combination) that was pressed and how long it was
pressed.
Features of the Keypad Interface Controller:
• Synchronous to bus
• 32 bit AHB bus interface
• 32.768 kHz sample clock
• Debouncing process (0 to 100 ms, 10 ms resolution) duration programmable by controller
• Module sends an interrupt, whenever a change occurs
• Up to 8 rows and 8 columns of a standard keypad matrix possible
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