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AT90S8414
Preliminary
The SRAM Data Memory - Internal and External” for description of the External SRAM pin functions. When the SRE
bit is cleared (zero), the external data SRAM is disabled, and the normal pin and data direction settings are used.
Bit 6 - SRW : External SRAM Wait State:
When the SRW bit is set (one), a one cycle wait state is inserted in the external data SRAM access cycle. When the SRW
bit is cleared (zero), the external data SRAM access is executed with the normal two cycle scheme. See Figure 23
External Data SRAM Memory Cycles without Wait State and Figure 24: External Data SRAM Memory Cycles with
Wait State.
Bit 5 - SE : Sleep Enable:
The SE bit must be set (one) to make the MCU enter the sleep mode when the SLEEP instruction is executed. To avoid
the MCU entering the sleep mode unless it is the programmers purpose, it is recommended to set the Sleep Enable SE bit
just before the execution of the SLEEP instruction.
Bit 4 - SM : Sleep Mode:
This bit selects between the two available sleep modes. When SM is cleared (zero), Idle Mode is selected as Sleep Mode.
When SM is set (one), Power Down mode is selected as sleep mode. For details, refer to the paragraph “Sleep Modes”
below.
Bit 3, 2 - ISC11, ISC10 : Interrupt Sense Control 1 bit 1 and bit 0:
The External Interrupt 1 is activated by the external pin INT1 if the SREG I-flag and the corresponding interrupt mask in
the GIMSK is set. The level and edges on the external INT1 pin that activate the interrupt are defined in the following
table:
Table 4: Interrupt 1 Sense Control
ISC11
ISC10
Description
0
0
The low level of INT1 generates an interrupt request.
0
1
Reserved
1
0
The falling edge of INT1 generates an interrupt request.
1
1
The rising edge of INT1 generates an interrupt request.
Note: When changing the ISC11/ISC10 bits, INT1 must be disabled by clearing its Interrupt Enable bit in the GIMSK
Register. Otherwise an interrupt can occur when the bits are changed.
Bit 1, 0 - ISC01, ISC00 : Interrupt Sense Control 0 bit 1 and bit 0:
The External Interrupt 0 is activated by the external pin INT0 if the SREG I-flag and the corresponding interrupt mask is
set. The level and edges on the external INT0 pin that activate the interrupt are defined in the following table:
Table 5: Interrupt 0 Sense Control
ISC01
ISC00
Description
0
0
The low level of INT0 generates an interrupt request.
0
1
Reserved
1
0
The falling edge of INT0 generates an interrupt request.
1
1
The rising edge of INT0 generates an interrupt request.
Note: When changing the ISC10/ISC00 bits, INT0 must be disabled by clearing its Interrupt Enable bit in the GIMSK
Register. Otherwise an interrupt can occur when the bits are changed.
Sleep Modes
To enter the sleep modes, the SE bit in MCUCR must be set (one) and a SLEEP instruction must be executed. If an
enabled interrupt occurs while the MCU is in a sleep mode, the MCU awakes, executes the instruction following SLEEP,
Содержание AT90S8414
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