STMPE1801 datasheet(35/60 Pages) STMICROELECTRONICS

35 / 60 page

STMPE1801

Keypad controller

Doc ID 17884 Rev 3

35/60

Keypad controller

The keypad controller consists of:

–

4 dedicated key controllers that support up to 4 simultaneous dedicated key

presses;

–

a keyscan controller support a maximum of 10 x 8 key matrix with detection of

three simultaneous key presses;

–

8 special function key controllers that support up to 8 simultaneous “special

function” key presses.

The key detection priority is dedicated, special function and normal keys.

Four of the row inputs can be configured as dedicated keys through the setting of Dkey0~3

bits of the KPC_CTRL register. The normal key matrix size can be configured through the

setting of KPC_ROW and KPC_COL registers. The scanning of each individual row input

and column output can be enabled or masked to support a key matrix of variable size from 1

x 1 to 10 x 8. It is allowed to have other 8 special function keys incorporated in the key

matrix.

The operation of the keypad controller is enabled by the SCAN bit of KPC_CTRL register.

Every key activity detected is de-bounced for a period set by the DB_1~7 bits of KPC_CTRL

The key data, indicating the key coordinates and its status (up or down), is loaded into the

FIFO at the end of a specified number of scanning cycles (set by SCAN_COUNT0~3 bits of

KPC_CTRL_MID register). An interrupt is generated when a new set of key data is loaded.

The FIFO has a capacity for ten sets of key data. Each set of key data consists of 5 bytes of

information when any of the four dedicated keys is enabled. It is reduced to 4 bytes when no

dedicated key is involved. When the FIFO is full before its content is read, an overflow signal

is generated while the FIFO will continue to hold its content but forbid loading of new key

data set.

STMPE1801 데이터시트(PDF) 35 Page - STMicroelectronics