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ADP5587 数据表(PDF) 11 Page - Analog Devices |
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ADP5587 数据表(HTML) 11 Page - Analog Devices |
11 / 24 page ADP5587 Rev. B | Page 11 of 24 Keypad Lock/Unlock Feature The ADP5587 has a locking feature that allows the user to lock the keypad or GPIs (configured to be part of the event table). When enabled, the keypad lock can prevent generation of key event interrupts and prevent key events from being recorded in the key event table. This feature comprises the Unlock Key 1 and Unlock Key 2 registers (Register 0x0F and Register 0x10, respectively), the keypad lock interrupt mask and keypad unlock timers (Register 0x0E), and the LCK1, LCK2, and keylock enable (K_LCK_EN) bits (Register 0x03). The unlock keys can be programmed with any value of the keys in the keypad matrix or any GPI event values that are part of the key event table. When the keypad lock interrupt mask timer is enabled, the user must press two specific keys before a keylock interrupt is generated or keypad events are recorded. After the keypad is locked (set Bit 6, Register 0x03, to enable the lock), the first time that the user presses any key, a key event interrupt is generated. No additional interrupt is generated unless both unlock key sequences are correct. If the correct unlock keys are not pressed before the mask timer expires, the state machine starts over. The first key event inter- rupt is generated to allow the software to see that the user has pressed a key so that the host can turn on the LCD and display the unlock message. The host then reads the lock status register to see if the keypad is unlocked. After the first key event interrupt, the state machine does not interrupt the processor again unless the correct sequence is keyed. The state machine is reset if the correct sequences are not keyed before the keypad lock interrupt mask timer expires. The state of the keypad lock interrupt mask bit (Register 0x01, Bit 2) in the configuration register determines whether the interrupt pin is asserted when the keylock interrupt status bit (Register 0x02, Bit 2) is set. Setting the keylock interrupt mask bit causes the INT pin to be asserted when the keylock interrupt status bit is set in Register 0x02; clearing that bit masks the interrupt, causing the interrupt pin not to respond to the keylock interrupt status bit. The mask interrupt timer should be set for the time that it takes for the LCD to dim or turn off so that, if a key is pressed, the backlight is set to bright mode again or reset to turn on the LCD. When the unlock mask interrupt timer equals 0, only the correct unlock sequence can generate an interrupt. Disabling the unlock mask interrupt timer allows the processor to remain undisturbed for situations in which the user, for example, has the phone in a pocket or purse and the keys are constantly pressed. The flowchart in Figure 11 shows the interaction of interrupt enable, key event counter, key event interrupt status, and interrupt generation. KEY EVENT INTERRUPT KEYLOCK INTERRUPT OVERFLOW INTERRUPT GPIO INTERRUPT INT OR INTERRUPT CONFIGURATION OVR_FLOW_ IEN K_LCK_IM GPI_IEN KE_IEN GPIEM_ CFG KEYPAD LOCK INTERRUPT MASK TIMER K_LCK_EN INT LOGIC VCC Figure 13. INT Pin Drive |
类似零件编号 - ADP5587_1 |
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类似说明 - ADP5587_1 |
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