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ADP5587 Arkusz danych(PDF) 8 Page - Analog Devices |
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ADP5587 Arkusz danych(HTML) 8 Page - Analog Devices |
8 / 24 page ADP5587 Rev. B | Page 8 of 24 THEORY OF OPERATION CONTROL REGISTERS CONTROL INTERFACE C9 C8 A0 A1 A2 A3 A4 A5 A6 A7 B0 B1 B2 B3 B4 B5 B6 B7 C0 C1 C2 C3 C4 C5 C6 C7 D0 D1 D2 D3 D4 D5 D6 D7 E0 E1 E2 E3 E4 E5 E6 E7 F0 F1 F2 F3 F4 F5 F6 F7 G0 G1 G2 G3 G4 G5 G6 G7 H0 H1 H2 H3 H4 H5 H6 H7 I0 I1 I2 I3 I4 I5 I6 I7 J0 J1 J2 J3 J4 J5 J6 J7 SCL SDA RST INT VCC GND VCC SCL SDA 19 21 23 22 18 17 20 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ADP5587 RST INT Figure 9. Typical Operating Circuit The ADP5587 is a GPIO expander that can be configured either as an 18 I/O port expander or as a 10 column × 8 row keypad matrix (80 keys maximum). It is ideal for cellular phone designs and other portable devices that require a large extended keypad and/or expanded I/Os. When smaller size keypads are required, unused GPIOs in the keypad matrix can be used as I/Os (GPOs and GPIs). All GPIOs (rows and columns) default to GPIs at power-up with pull-ups and debounce enabled. KEYPAD OPERATION Any number of rows and columns, up to 10 columns × 8 rows, can be configured to be part of the keypad matrix. The rows and columns that make up the keypad matrix must be configured by setting the corresponding bits in Register 0x1D to Register 0x1F. Key presses and releases appear in the key event table/registers with a decimal value of 1 (0x01 hexadecimal or 0000001 binary) through a decimal value of 80 (0x50 hexadecimal or 1010000 binary). See Table 9 for key event number assignments. The keypad, in idle mode, is configured with columns driven low and rows as inputs configured high with pull-up resistors. Table 9. Key Event Number Assignment Table Row C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 R0 1 2 3 4 5 6 7 8 9 10 R1 11 12 13 14 15 16 17 18 19 20 R2 21 22 23 24 25 26 27 28 29 30 R3 31 32 33 34 35 36 37 38 39 40 R4 41 42 43 44 45 46 47 48 49 50 R5 51 52 53 54 55 56 57 58 59 60 R6 61 62 63 64 65 66 67 68 69 70 R7 71 72 73 74 75 76 77 78 79 80 When one key press or multiple key presses (short between column and row) occur, the internal state machine checks the row pins to determine which one is driven low and then triggers an internal interrupt. The state machine then starts a key scan cycle to determine which columns are involved in the key press. After a key has been pressed for 25 ms, the state machine sets the appropriate key number in the key event status register with the key-pressed bits set (the MSB in the key event register) in the order detected. The state machine then sets the KE_INT bit in Register 0x02. If the KE_IEN field in Register 0x01 is set, an interrupt is sent to the host processor. |
Podobny numer części - ADP5587_1 |
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Podobny opis - ADP5587_1 |
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