W681308
XXXX PRODUCT DESCRIPTION
14.
14.1
Serial Peripheral Interface
Overview
W681308 built in a serial peripheral interface (SPI) port which is a 4-pin (SCLK, CS, SDI, SDO) SPI Interface. This SPI
interface makes W681308 an easy to control 4-pin SPI device including SPI data flash, SPI LCM, Nuvoton Pro-X SLIC
CODEC etc. This device has various clock speed and data format by setting relative control registers. The SPI module can
be operated at clock rates of up to MCU clock rate.
Figure 12 SPI Block Diagram
14.2
Data and Signal Format of SPI
There are 5 control bits (CSN_ADD, CSN_MORE, CK_MORE, CP and CI) to decide the SPI control signal format. Register
0x14AB has detail description of the control bits.
The packet and page data format is separated to 2 fields: Command field and the Data field. Command field (0 ~ 5 bytes)
consists of control instruction/code and access address (TX only). Data field (0 ~ 256 bytes) consists of write and read data
of serial data flash (TX/RX). All Command and Data bytes are send MSB first. Command and Data field length can be
programmed in CMD_LEN (0x14A1[2:0]) and DATA_LEN (0x14A2[7:0]) register fields. It can be bypassed to write control bit
CMD_BYPASS or disable the DATA_ENB. The max command field length is 5 bytes. The max data field length is 256 bytes
in unidirectional mode, and 128 bytes in bidirectional mode. Thirteen examples are provided for reference.
14.3
FSM of SPI
There are 3 states in the SPI Finite State Machine (FSM) module. The initial state is IDLE when power on.
IDLE
After enable the SPI function (write 0x14A0[7] =1), the FSM start to wait for MCU control (write 0x14A1) to change to next
state. If the CMD BYPASS flag (0x14A1[5]) is true, the FSM will change to DATA state, then force control logic to shift in/out
the data bytes sequentially. If the CMD BYPASS flag ( 0x14A1[5]) is false, the FSM will change to the CMD state, then force
control logic to shift out the command bytes sequentially to external SPI device.
Command (CMD)
47
Rev1.2
NUVOTEM TALEMA [ NUVOTEM TALEMA ]
