UM0851 Datasheet, PDF(178/245 Page) STMicroelectronics – SPEAr is a family of highly customizable ARM-based embedded

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UM0851 Datasheet, PDF (178/245 Pages) STMicroelectronics – SPEAr is a family of highly customizable ARM-based embedded

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Human interface device (HID) drivers

UM0851

Table 46. Configuration options (continued)

Configuration option

Comment

CONFIG_TOUCHSCREEN_SPEAR

CONFIG_TOUCHSCREEN_SPEAR_DEBUG

This option enables the SPEAr touchscreen

device.

This option enables debug prints for the SPEAr

touchscreen device.

CONFIG_INPUT_EVDEV

This option make input device events be

accessible under char device 13:64+ -

/dev/input/eventX in a generic way

Note:

7.1.5

Both CONFIG_INPUT_TOUCHSCREEN and CONFIG_TOUCHSCREEN_SPEAR must be

defined.

â CONFIG_TOUCHSCREEN_SPEAR is visible only if

CONFIG_INPUT_TOUCHSCREEN is defined.

â CONFIG_INPUT_TOUCHSCREEN selects the touchscreen.

â CONFIG_TOUCHSCREEN_SPEAR selects the SPEAr device for touchscreen.

References

â Linux-2.6.27/Documentation/input/input.txt

â Linux-2.6.27/Documentation/input/input-programming.txt

7.2

7.2.1

Keypad driver

This section describes the keypad controller driver. This controller and driver are present on

SPEAr300 only.

Hardware overview

SPEAr300 has a GPIO/keypad block which is a two-mode input and output port.

In summary, it provides:

â 18-bit general-purpose parallel port with input or output single pin programmability

â 81-key keypad (9x9 matrix)

The selection between the two modes is a programmable bit. The mode control bits in the

mode control register must be set to [00] to enable the keypad mode.

When the keypad mode is selected, it is possible to read the value of the externally

connected keyboard, scanned at programmed rate.

The keypad may contain up to 81 keys. Eighteen (18) port pins provide a 9x9 scanning

matrix. Nine (9) of the pins are strobes and nine (9) of the pins are inputs.

The circuitry scans the keys at a rate of 10, 20, 40 or 80 ms, controlled by the software. Two

successive cycles are needed to validate a key. Only one key is allowed to be down in a

scan cycle. Each valid key condition causes the value of the key to be written to a register

and an interrupt to be set. The key value is coded on eight bits. The lower nibble refers to the

column number (0, 1,2â¦8) while the higher nibble gives the row number (0,1, 2â¦8) of the

pressed key.

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Doc ID 16604 Rev 2

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