STMPE1601 STMicroelectronics, STMPE1601 Datasheet - Page 41

• Manufacturer Part Number: STMPE1601
• Description: 16-bit Enhanced Port Expander With Keypad And Pwm Controller Xpander Logic
• Manufacturer: STMicroelectronics

STMPE1601
12
Keypad controller
The keypad controller consists of:
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.
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
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4 dedicated key controllers that support up to 4 simultaneous dedicated key
presses;
a keyscan controller and two normal key controllers that 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.
Keypad controller
Input 0-7
Keypad Matrix
Output 0-7
Keypad controller
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