STMPE2403 datasheet(46/63 Pages) STMICROELECTRONICS

46 / 63 page

Keypad controller

STMPE2403

46/63

Keypad controller

The keypad controller consists of: 1) four dedicated key controllers that support up to four

simultaneous dedicated key presses; 2) a key scan controller and two normal key controllers

that support a maximum of 12x8 key matrix with detection of three simultaneous key

presses; 3) eight special function key controllers that support up to eight simultaneous

special function key presses.

Four of the column inputs can be configured as dedicated keys through the setting of

Dkey0~3 bits of KPC_ctrl register.

The normal key matrix size is configurable 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 1x1 to 12x8. It is allowed to have

another eight 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 ScanCount0~3 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

Input 0-7

Output 0-11

Keypad Matrix

STMPE2403 数据表(PDF) 46 Page - STMicroelectronics