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Linux/Documentation/smsc_ece1099.txt

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

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