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ADP5588 数据表(PDF) 9 Page - Analog Devices |
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ADP5588 数据表(HTML) 9 Page - Analog Devices |
9 / 28 page ADP5588 Rev. A | Page 9 of 28 Autoincrement The ADP5588 features automatic increment during I2C read access. This allows the user to increment the address pointer without having to send a read command for subsequent addresses. This minimizes processor intervention and, therefore, saves processor bandwidth and current drain. Bit 7 of Register 0x01 must be set to initiate autoincrement (see Figure 16 for the full write and read sequence). Key Event Interrupt On a key event (KE) interrupt, the processor reads the interrupt register to determine the cause of the interrupt. If the KE_INT bit in Register 0x02 is the cause of the interrupt, the state machine sets the KE_INT bit and reads the key event count from the KEC[3:0] field in Register 0x03 to determine the number of events. It then reads the INT_STAT register (Register 0x02) to make sure that no new events have come in. After all the events are read, the KEC field is decremented to zero (KEC =0) and the KE_INT bit can be cleared by writing a 1 to it. Both key presses and key releases are capable of generating key event interrupts. The KE_INT bit cannot be cleared, and the INT pin cannot be deasserted, until the FIFO is cleared of all events. KP_MODE KEC REG. 0x1D THROUGH 0x1F REG. 0x03 READ KE(s) TO CLEAR INT DRIVE KE_INT REG. 0x02 WRITE 1 TO CLEAR KE_IEN REG. 0x01 AND Figure 6. Key Event Interrupt Generation Keypad Lock/Unlock Feature The ADP5588 has a locking feature that allows the user to lock the keypad or GPIs (configured to be part of the event table). Once enabled, the keypad lock can prevent generation of key event interrupts and key events to be recorded in the key event table. This feature comprises the Unlock Key 1 and Unlock Key 2 registers (Register 0x0F and Register 0x10), the keypad lock interrupt mask, the keypad unlock timers (Register 0x0E), and the LCK1 and LCK2 bits, and the keylock enable bit (Register 0x03). The unlock keys can be programmed with any value of the keys in the keypad matrix or any GPI 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; then a keylock interrupt is generated. If the correct unlock keys are not pressed before the mask timer expires, the state machine starts over. The first key event interrupt 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 resets 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 has the phone in a pocket or purse and the keys are constantly pressed. The flow chart in Figure 6 shows the interaction of the interrupt mask timer and interrupt generation. GENERAL-PURPOSE INPUTS AND OUTPUTS The ADP5588 supports up to 18 programmable GPIOs that can be configured to address a variety of uses. Figure 7 shows the makeup of a typical GPIO block where GPIOx represents any of the 18 I/O lines. DEBOUNCE VCC Dx_DIR Dx_OUT Dx_IN Dx_IN_DBNC Dx_PULL VCC GPIOx Figure 7. Typical GPIO Block General Purpose Inputs (GPI) The ADP5588 allows the user to configure all or some of its GPIOs into GPIs (general-purpose inputs). After the GPIOs are configured as GPIs, the user can opt to also turn on pull-up resistors and interrupt generation capability, thus reducing the amount of software monitoring and processor interaction and saving power. The programmed level of the GPI interrupt determines the active level of the GPI pin. For example, if a GPI interrupt level |
类似零件编号 - ADP5588 |
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类似说明 - ADP5588 |
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