61 lines
2.5 KiB
ReStructuredText
61 lines
2.5 KiB
ReStructuredText
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Msc Keyboard Scan Expansion/GPIO Expansion device
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What is smsc-ece1099?
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The ECE1099 is a 40-Pin 3.3V Keyboard Scan Expansion
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or GPIO Expansion device. The device supports a keyboard
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scan matrix of 23x8. The device is connected to a Master
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via the SMSC BC-Link interface or via the SMBus.
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Keypad scan Input(KSI) and Keypad Scan Output(KSO) signals
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are multiplexed with GPIOs.
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Interrupt generation
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--------------------
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Interrupts can be generated by an edge detection on a GPIO
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pin or an edge detection on one of the bus interface pins.
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Interrupts can also be detected on the keyboard scan interface.
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The bus interrupt pin (BC_INT# or SMBUS_INT#) is asserted if
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any bit in one of the Interrupt Status registers is 1 and
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the corresponding Interrupt Mask bit is also 1.
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In order for software to determine which device is the source
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of an interrupt, it should first read the Group Interrupt Status Register
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to determine which Status register group is a source for the interrupt.
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Software should read both the Status register and the associated Mask register,
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then AND the two values together. Bits that are 1 in the result of the AND
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are active interrupts. Software clears an interrupt by writing a 1 to the
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corresponding bit in the Status register.
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Communication Protocol
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- SMbus slave Interface
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The host processor communicates with the ECE1099 device
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through a series of read/write registers via the SMBus
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interface. SMBus is a serial communication protocol between
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a computer host and its peripheral devices. The SMBus data
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rate is 10KHz minimum to 400 KHz maximum
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- Slave Bus Interface
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The ECE1099 device SMBus implementation is a subset of the
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SMBus interface to the host. The device is a slave-only SMBus device.
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The implementation in the device is a subset of SMBus since it
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only supports four protocols.
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The Write Byte, Read Byte, Send Byte, and Receive Byte protocols are the
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only valid SMBus protocols for the device.
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- BC-LinkTM Interface
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The BC-Link is a proprietary bus that allows communication
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between a Master device and a Companion device. The Master
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device uses this serial bus to read and write registers
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located on the Companion device. The bus comprises three signals,
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BC_CLK, BC_DAT and BC_INT#. The Master device always provides the
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clock, BC_CLK, and the Companion device is the source for an
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independent asynchronous interrupt signal, BC_INT#. The ECE1099
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supports BC-Link speeds up to 24MHz.
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