COP8SBR9 NSC [National Semiconductor], COP8SBR9 Datasheet - Page 60

• Manufacturer Part Number: COP8SBR9
• Description: 8-Bit CMOS Flash Based Microcontroller with 32k Memory, Virtual EEPROM and Brownout
• Manufacturer: NSC [National Semiconductor]

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17.0 MICROWIRE/PLUS
17.1.2.1 Alternate SK Phase Operation and SK Idle
Polarity
The device allows either the normal SK clock or an alternate
phase SK clock to shift data in and out of the SIO register. In
both the modes the SK idle polarity can be either high or low.
The polarity is selected by bit 5 of Port G data register. In the
normal mode data is shifted in on the rising edge of the SK
clock and the data is shifted out on the falling edge of the SK
clock. The SIO register is shifted on each falling edge of the
SK clock. In the alternate SK phase operation, data is shifted
SK Phase
Alternate
Alternate
Normal
Normal
FIGURE 30. MICROWIRE/PLUS SPI Mode Interface Timing, Normal SK Mode, SK Idle Phase being Low
G6 (SKSEL)
Config. Bit
TABLE 25. MICROWIRE/PLUS Shift Clock Polarity and Sample/Shift Phase
0
1
0
1
Port G
FIGURE 29. MICROWIRE/PLUS Application
(Continued)
G5 Data
Bit
0
0
1
1
SO Clocked Out On:
SK Falling Edge
SK Falling Edge
60
SK Rising Edge
SK Rising Edge
in on the falling edge of the SK clock and shifted out on the
rising edge of the SK clock. Bit 6 of Port G configuration
register selects the SK edge.
A control flag, SKSEL, allows either the normal SK clock or
the alternate SK clock to be selected. Refer to Table 25 for
the appropriate setting of the SKSEL bit. The SKSEL is
mapped into the G6 configuration bit. The SKSEL flag will
power up in the reset condition, selecting the normal SK
signal provided the SK Idle Polarity remains LOW.
SI Sampled On:
SK Falling Edge
SK Falling Edge
SK Rising Edge
SK Rising Edge
10138936
10138935
SK Idle
Phase
High
High
Low
Low