参数资料
型号: ST7PL35F2MCXXXRE
厂商: STMICROELECTRONICS
元件分类: 微控制器/微处理器
英文描述: 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO20
封装: 0.300 INCH, ROHS COMPLIANT, PLASTIC, SOP-20
文件页数: 144/168页
文件大小: 2955K
代理商: ST7PL35F2MCXXXRE
Obsolete
Product(s)
- Obsolete
Product(s)
ST7L34, ST7L35, ST7L38, ST7L39
77/168
SERIAL PERIPHERAL INTERFACE (cont’d)
11.4.3.2 Slave Select Management
As an alternative to using the SS pin to control the
Slave Select signal, the application can choose to
manage the Slave Select signal by software. This
is configured by the SSM bit in the SPICSR regis-
ter (see Figure 51).
In software management, the external SS pin is
free for other application uses and the internal SS
signal level is driven by writing to the SSI bit in the
SPICSR register.
In Master mode:
–SS internal must be held high continuously
In Slave Mode:
There are two cases depending on the data/clock
timing relationship (see Figure 50):
If CPHA = 1 (data latched on second clock edge):
–SS internal must be held low during the entire
transmission. This implies that in single slave
applications the SS pin either can be tied to
VSS, or made free for standard I/O by manag-
ing the SS function by software (SSM = 1 and
SSI = 0 in the in the SPICSR register)
If CPHA = 0 (data latched on first clock edge):
–SS internal must be held low during byte
transmission and pulled high between each
byte to allow the slave to write to the shift reg-
ister. If SS is not pulled high, a Write Collision
error will occur when the slave writes to the
shift register (see Section 11.4.5.3).
Figure 50. Generic SS Timing Diagram
Figure 51. Hardware/Software Slave Select Management
MOSI/MISO
Master SS
Slave SS
(if CPHA = 0)
Slave SS
(if CPHA = 1)
Byte 1
Byte 2
Byte 3
1
0
SS internal
SSM bit
SSI bit
SS external pin
1
相关PDF资料
PDF描述
ST7PL35F2UA/XXXE 8-BIT, MROM, 8 MHz, MICROCONTROLLER, QCC20
ST7L35F2UA/XXXRE 8-BIT, MROM, 8 MHz, MICROCONTROLLER, QCC20
ST7L35F2UC/XXXRE 8-BIT, MROM, 8 MHz, MICROCONTROLLER, QCC20
ST7L39F2MC/XXXE 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PDSO20
ST7L39F2UC/XXXRE 8-BIT, MROM, 8 MHz, MICROCONTROLLER, QCC20
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