ADI 公司的ADP5588是移动I/O扩展器和QWERTY(标准打字机键盘)手机键盘控制器. QWERTY手机需要大的键盘阵列和扩展的I/O线,而ADP5588有足够的能力来处理所有键扫描,译码和标识按压键,并通过I2C接口告知和中断,释放了主微处理器监视键盘的工作量,从而最小化电流消耗和增加了处理器带宽. ADP5588猪主要用在需要大键盘阵列的QWERTY手机.本文介绍了ADP5588的主要特性,方框图以及典型工作电路和详细的ADP5588应用方框图.
Mobile I/O Expander and QWERTY Keypad Controller ADP5588
The ADP5588 is an I/O port expander and keypad matrix designed for QWERTY type phones that require a large keypad matrix and expanded I/O lines. I/O expander ICs are used in mobile platforms as a solution to the limited number of GPIOs available in the main processor. In its small 4 mm × 4 mm package, the ADP5588 contains enough power to handle all key scanning and decoding and flag the processor of key presses and releases via the I2C interface and interrupt. It frees the main microprocessor from having to monitor the keypad, thereby minimizing current drain and increasing processor bandwidth. It is also equipped with a buffer/FIFO and key event counter to handle and keep track of up to 10 unprocessed key or GPI events with overflow wrap and interrupt capability. The ADP5588 has a keylock capability with an option to trigger or not trigger an interrupt at key presses and releases. All com- munication to the main processor is done using one interrupt line and two I2C-compatible interface lines. The ADP5588 can be configured to have a keypad matrix of up to 8 rows × 10 columns (a maximum of 80 keys). When used for smaller keypad matrices, unused row and column pins can be reconfigured to act as general-purpose inputs, outputs, or light sensor inputs. R0, R1, R2, R3, R4, R5, R6, and R7 denote the row pins of the matrix, while C0, C1, C2, C3, C4, C5, C6, C7, C8, and C9 denote the column pins. At power-up, all rows and columns default as GPIs and must be programmed to function as part of the keypad matrix, GPOs, or light sensor inputs. In addition to keypad and GPIO functionalities, C8 and C9 can also be configured as light sensor inputs. When configured as keypad lines, the function of the C8 and C9 lines is straightforward: the control interface disconnects these lines from the comparator inputs, disables the light sensor comparator, and connects them to the keypad columns of the keypad matrix. When used as light sensor comparator inputs, the control interface disconnects these pins from the keypad, enables the comparators, and connects these lines to the com- parator inputs. Two external capacitors (0.1 μF) are required when these pins are configured as light sensor inputs. When used as GPIOs, these pins are removed from the keypad and the light sensor interface, and the light sensor comparators are disabled, along with the logic for the sensors.
ADP5588主要特性:
18-GPIO port expander or 10 × 8 keypad matrix
GPIOs configurable to GPIs, GPOs, and keypad rows or columns
Dual light sensor inputs (C8 and C9)
I2C interface
I2C register read autoincrement
1.8 V to 3.0 V operation
Keypad lock capability
Open-drain interrupt output
Key press and key release interrupts GPI interrupt with level programmability
Programmable pull-ups Key event counter with overflow interrupt
50 μs debounce on the reset line and GPIs
1 μA typical idle current, 55 μA typical polling current drain for one key press
Small 4 mm × 4 mm LFCSP package
ADP5588应用:
Keypad and I/O expander designed for QWERTY type phones that require a large keypad matrix
图1.ADP5588功能方框图
图2.ADP5588典型工作电路
图3.详细的ADP5588应用方框图
图4.综合方框图
