1================================================= 2Msc Keyboard Scan Expansion/GPIO Expansion device 3================================================= 4 5What is smsc-ece1099? 6---------------------- 7 8The ECE1099 is a 40-Pin 3.3V Keyboard Scan Expansion 9or GPIO Expansion device. The device supports a keyboard 10scan matrix of 23x8. The device is connected to a Master 11via the SMSC BC-Link interface or via the SMBus. 12Keypad scan Input(KSI) and Keypad Scan Output(KSO) signals 13are multiplexed with GPIOs. 14 15Interrupt generation 16-------------------- 17 18Interrupts can be generated by an edge detection on a GPIO 19pin or an edge detection on one of the bus interface pins. 20Interrupts can also be detected on the keyboard scan interface. 21The bus interrupt pin (BC_INT# or SMBUS_INT#) is asserted if 22any bit in one of the Interrupt Status registers is 1 and 23the corresponding Interrupt Mask bit is also 1. 24 25In order for software to determine which device is the source 26of an interrupt, it should first read the Group Interrupt Status Register 27to determine which Status register group is a source for the interrupt. 28Software should read both the Status register and the associated Mask register, 29then AND the two values together. Bits that are 1 in the result of the AND 30are active interrupts. Software clears an interrupt by writing a 1 to the 31corresponding bit in the Status register. 32 33Communication Protocol 34---------------------- 35 36- SMbus slave Interface 37 The host processor communicates with the ECE1099 device 38 through a series of read/write registers via the SMBus 39 interface. SMBus is a serial communication protocol between 40 a computer host and its peripheral devices. The SMBus data 41 rate is 10KHz minimum to 400 KHz maximum 42 43- Slave Bus Interface 44 The ECE1099 device SMBus implementation is a subset of the 45 SMBus interface to the host. The device is a slave-only SMBus device. 46 The implementation in the device is a subset of SMBus since it 47 only supports four protocols. 48 49 The Write Byte, Read Byte, Send Byte, and Receive Byte protocols are the 50 only valid SMBus protocols for the device. 51 52- BC-LinkTM Interface 53 The BC-Link is a proprietary bus that allows communication 54 between a Master device and a Companion device. The Master 55 device uses this serial bus to read and write registers 56 located on the Companion device. The bus comprises three signals, 57 BC_CLK, BC_DAT and BC_INT#. The Master device always provides the 58 clock, BC_CLK, and the Companion device is the source for an 59 independent asynchronous interrupt signal, BC_INT#. The ECE1099 60 supports BC-Link speeds up to 24MHz. 61