MEC1322 Datasheet, PDF (314/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
FIGURE 27-4:
DUAL FAST READ FLASH COMMAND
MCLK
BIOEN
TX_DATA
Write TX_Data
TX_DATA Buffer Empty (TxBE)
Rx_DATA Buffer Full (RxBF)
Read RX_Data
RX_DATA
SPDOUT Pin
SPDIN1
SPDIN2
SPCLKO
Comm
and
Address
23:16
Address
15:8
Address
7:0
Dummy Byte
Byte 1
Command Byte
Address [23:16]
Driven by Master
Address Byte
[16:8]
76543210765432107654321076543210
Address Byte
[7:0]
7654321076543210765432107654321076543210
MCLK
BIOEN
TX_DATA
Write TX_Data
TX_DATA Buffer Empty (TxBE)
Rx_DATA Buffer Full (RxBF)
Read RX_Data
RX_DATA
SPDOUT Pin
SPDIN1
SPDIN2
SPCLKO
Byte 2
Byte 3
Byte 4
Dummy Byte
BYTE 1
BYTE 2
BYTE 3
Driven by Slave
6 4 2 0 6 4 2 0 6 4 2 06 4 2 0
75 3 1 75 3 1 75 3 175 3 1
6 4 2 0 6 4 2 0 6 4 2 06 4 2 0
BYTE 4
Note: When the SPI core is used for flash commands, like the Dual Read command, the host discards the bytes
received during the command, address, and dummy byte portions of the transaction.
27.10.4 HOW BIOEN BIT CONTROLS DIRECTION OF SPDOUT BUFFER
When the SPI is configured for Half Duplex mode or Dual Mode the SPDOUT pin operates as a bi-directional signal.
The BIOEN bit is used to determine the direction of the SPDOUT buffer when a byte is transmitted. Internally, the BIOEN
bit is sampled to control the direction of the SPDOUT buffer when the TX_DATA value is loaded into the transmit shift
register. The direction of the buffer is never changed while a byte is being transmitted.
Since the TX_DATA register may be written while a byte is being shifted out on the SPDOUT pin, the BIOEN bit does
not directly control the direction of the SPDOUT buffer. An internal DIRECTION bit, which is a latched version of the
BIOEN bit determines the direction of the SPDOUT buffer. The following list summarizes when the BIOEN bit is sam-
pled.
DS00001719D-page 314
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