STMPE1601 datasheet(42/61 Pages) STMICROELECTRONICS

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Keypad controller

STMPE1601

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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 8 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.

Four of the column 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 output and column input can be

enabled or masked to support a key matrix of variable size from 1 x 1 to 8 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 will be de-bounced for a period set by the DB_0~7 bits of

KPC_CTRL register before a key press or key release is confirmed and updated into the

output FIFO. 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_ROW_MSB register). An interrupt will be 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 will be generated while the FIFO will continue to hold its

content but forbid loading of new key data set.

Figure 8.

Keypad controller

The keypad column inputs enabled by the KPC_col register are normally 'high', with the

corresponding input pins pulled up by resistors internally. After reset, all the keypad row

outputs enabled by the KPC_row register are driven 'low'. If a key is pressed, its

Input 0-7

Output 0-7

Keypad Matrix

STMPE1601 데이터시트(PDF) 42 Page - STMicroelectronics