Rainbow-electronics W90P710CDG Manual de usuario descargar pdf (Pagina 482)

100

101

W90P710CD/W90P710CDG

Publication Release Date: September 19, 2006

- 483 - Revision B2

6.19 Universal Serial Interface

The USI is a synchronous serial interface performs a serial-to-parallel conversion on data characters

received from the peripheral, and a parallel-to-serial conversion on data characters received from

CPU. This interface can drive one external peripherals and is seen as the master. It can generate an

interrupt signal when data transfer is finished and can be cleared by writing 1 to the interrupt flag. The

active level of device/slave select signal can be chosen to low active or high active, which depends on

the peripheral it’s connected. Writing a divisor into DIVIDER register can program the frequency of

serial clock output. This master core contains four 32-bit transmit/receive buffers, and can provide

burst mode operation. The maximum bits can be transmitted/received is 32 bits, and can

transmit/receive data up to four times successive.

The USI (Microwire/SPI) Master Core includes the following features:

• AMBA APB interface compatible

• Support USI (Microwire/SPI) master mode

• Full duplex synchronous serial data transfer

• Variable length of transfer word up to 32 bits

• Provide burst mode operation, transmit/receive can be executed up to four times in one transfer

• MSB or LSB first data transfer

• Rx and Tx on both rising or falling edge of serial clock independently

• 1 slave/device select lines

• Fully static synchronous design with one clock domain

6.19.1 USI Timing Diagram

The timing diagram of USI is shown as following.

MSB

(Tx[7])

LSB

(Tx[0])

MSB

(Rx[7])

LSB

(Rx[0])

mw_ss_o

mw_sclk_o

mw_so_o

mw_si_i

CNTRL[LSB]=0, CNTRL[Tx_NUM]=0x0, CNTRL[Tx_BIT_LEN]=0x08,

CNTRL[Tx_NEG]=1, CNTRL[Rx_NEG]=0, SSR[SS_LVL]=0

Tx[6] Tx[5] Tx[4] Tx[3] Tx[2] Tx[1]

Rx[6] Rx[5] Rx[4] Rx[3] Rx[2] Rx[1]

Fig. 6.19.1.1 USI Timing

1 2 ... 477 478 479 480 481 482 483 484 485 486 487 ... 551 552

Rainbow-electronics W90P710CDG Manual de usuario Pagina 482

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Rainbow-electronics W90P710CDG Manual de usuario Pagina 482

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