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Documentation / smsc_ece1099.txt




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Based on kernel version 3.9. Page generated on 2013-05-02 23:14 EST.

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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