參數(shù)資料
型號(hào): ST52F514F3M6
英文描述: IC MAX 7000 CPLD 256 256-FBGA
中文描述: 微控制器
文件頁數(shù): 100/106頁
文件大?。?/td> 648K
代理商: ST52F514F3M6
ST52F510/F513/F514
100/106
Figure 15.5 Clearing the WCOL bit (Write Collision Flag) Software Sequence
15.4.6 Overrun Condition.
An overrun condition occurs when the master
device has sent several data bytes and the slave
device hasn’t cleared the SPIF bit issued from the
previous data byte transmitted.
In this case, the receiver buffer contains the byte
sent after the SPIF bit was last cleared. A read to
the SPI_IN register returns this byte. All other
bytes are lost.
This
condition is not
peripheral.
detected by the SPI
15.4.7 Single Master and Multimaster Configu-
rations.
There are two types of SPI systems:
– Single Master System
– Multimaster System
Single Master System
A typical single master system may be configured,
using an ICU as the master and four ICUs as
slaves (see Figure 15.6).
The master device selects the individual slave
devices by using four pins of a parallel port to
control the four SS pins of the slave devices.
The SS pins are pulled high during reset since the
master device ports will be forced to be inputs at
that time, thus disabling the slave devices.
Note:
In order to prevent a bus conflict on the
MISO line the master allows only one active slave
device during a transmission.
For moresecurity, theslave device mayrespond to
the master with the data byte received. Then the
master willreceive the previous byte back from the
slave device if all MISO and MOSI pins are
connected and the slave has not written its
SPI_OUT register.
Other transmission securitymethods canuse ports
for handshake lines or data bytes with command
fields.
Multi-master System
A multi-master system may also be configured by
the user. Transfer of master control could be
implemented using a handshake method through
the I/O ports or by an exchange of code messages
through the serial peripheral interface system.
The multi-master system is principally handled by
the MSTR bit in the SPI_CR register and the
MODF bit in the SPI_STATUS_CR register.
Clearing sequence after SPIF = 1 (end of a data byte transfer)
1st Step
Read SPI_STATUS_CR
Read SPI_IN
Write SPI_IN
2nd Step
SPIF =0
WCOL=0
SPIF =0
WCOL=0
if no transfer has started
WCOL=1
if a transfer has started
before the 2nd step
Clearing sequence before SPIF = 1 (during a data byte transfer)
1st Step
2nd Step
WCOL=0
Read SPI_STATUS_CR
Read SPI_IN
Note:
Writing in SPI_OUT regis-
ter instead of reading in SPI_IN
do not reset WCOL bit
Read SPI_STATUS_CR
OR
THEN
THEN
THEN
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ST52F514FMB6 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:8-BIT INTELLIGENT CONTROLLER UNIT ICU Two Timer/PWMs, ADC, I2C, SPI, SCI
ST52F514FMM6 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:8-BIT INTELLIGENT CONTROLLER UNIT ICU Two Timer/PWMs, ADC, I2C, SPI, SCI
ST52F514G0B6 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Microcontroller
ST52F514G0M6 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Microcontroller
ST52F514G1B6 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Microcontroller