STMPE2401TBR STMicroelectronics, STMPE2401TBR Datasheet - Page 41

• Manufacturer Part Number: STMPE2401TBR
• Description: IC I/O EXPANDER I2C 24B 36TFBGA
• Manufacturer: STMicroelectronics

Specifications of STMPE2401TBR

• Interface: I²C
• Number Of I /o: 24
• Interrupt Output: Yes
• Frequency - Clock: 400kHz
• Voltage - Supply: 1.65 V ~ 1.95 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-TFBGA
• Includes: Keypad, POR, PWM
• For Use With: 497-6426 - BOARD EVAL BASED ON STMPE2401
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6133-2

STMPE2401
13.1
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
corresponding column input will become ‘LOW’ after making contact with the ‘LOW’ voltage
on its corresponding row output.
Once the key scan controller senses a ‘LOW’ input on any of the column inputs, the
scanning cycles will then start to determine the exact key that has been pressed. The twelve
row outputs will be driven ‘LOW’ one by one (if the row output is enabled) during each
scanning cycle. While one row is driven ‘LOW’, the other rows are driven ‘HIGH’. (The pull-
ups and pull-downs of row outputs are always disabled). If there is any column input sensed
as ‘LOW’ when a row is driven ‘LOW’, the key scan controller will then decode the key
coordinates (its corresponding row number and column number), save the key data into a
de-bounce buffer if available, confirm if it is a valid key press after de-bouncing, and update
the key data into output data FIFO if valid.
Registers in keypad controller
Table 37. Register in keypad controller
Address
0x6A
0x60
0x61
0x62
0x63
0x64
0x68
0x69
KPC_col
KPC_row_msb
KPC_row_lsb
KPC_ctrl_msb
KPC_ctrl_lsb
KPC_data_byte0
KPC_data_byte1
KPC_data_byte2
Register name
Keypad column scanning register
Keypad row scanning register
Keypad control register
Keypad data register
Description
Keypad controller
(during sequential
Auto-Increment
R/W)
Yes
Yes
Yes
Yes
Yes
No
No
No
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