2.8 MODA and MODB (MODA/LIR and MODB/VSTBY
參數(shù)資料
型號: MC68HC11F1CFN4R2
廠商: Freescale Semiconductor
文件頁數(shù): 72/158頁
文件大小: 0K
描述: IC MCU 1K RAM 4MHZ 68-PLCC
標準包裝: 1
系列: HC11
核心處理器: HC11
芯體尺寸: 8-位
速度: 4MHz
連通性: SCI,SPI
外圍設(shè)備: POR,WDT
輸入/輸出數(shù): 30
程序存儲器類型: ROMless
EEPROM 大?。?/td> 512 x 8
RAM 容量: 1K x 8
電壓 - 電源 (Vcc/Vdd): 4.75 V ~ 5.25 V
數(shù)據(jù)轉(zhuǎn)換器: A/D 8x8b
振蕩器型: 內(nèi)部
工作溫度: -40°C ~ 85°C
封裝/外殼: 68-LCC(J 形引線)
包裝: 剪切帶 (CT)
其它名稱: MC68HC11F1CFN4RCT
PIN DESCRIPTIONS
MC68HC11F1
2-6
TECHNICAL DATA
2.8 MODA and MODB (MODA/LIR and MODB/VSTBY)
During reset, MODA and MODB select one of the four operating modes. Refer to SEC-
After the operating mode has been selected, the LIR pin provides an open-drain output
to indicate that execution of an instruction has begun. The LIR pin is configured for
wired-OR operation (only pulls low). A series of E-clock cycles occurs during execution
of each instruction. The LIR signal is asserted (drives low) during the first E-clock cycle
of each instruction (opcode fetch). This output is provided for assistance in program
debugging.
The VSTBY pin is used to input RAM standby power. The MCU is powered from the
VDD signal unless the difference between the level of VSTBY and Vdd is greater than
one MOS threshold (about 0.7 volts). When these voltages differ by more than 0.7
volts, the internal 768-byte RAM and part of the reset logic are powered from VSTBY
rather than VDD. This allows RAM contents to be retained without VDD power applied
to the MCU. Reset must be driven low before VDD is removed and must remain low
until VDD has been restored to a valid level.
2.9 VRH and VRL
These pins provide the reference voltage for the analog-to-digital converter. Bypass
capacitors should be used to minimize noise on these signals. Any noise on VRH and
VRL will directly affect A/D accuracy.
2.10 R/W
In expanded and test modes, R/W indicates the direction of transfers on the external
data bus. A logic level one on this pin indicates that a read cycle is in progress. A logic
zero on this pin indicates that a write cycle is in progress and that no external device
should drive the data bus.
The E-clock can be used to enable external devices to drive data onto the data bus
during the second half of a read bus cycle (E clock high). R/W can then be used to
control the direction of data transfers. R/W drives low when data is being written to the
external data bus. R/W will remain low during consecutive data bus write cycles, such
as when a double-byte store occurs.
2.11 Port Signals
For the MC68HC11F1, 54 pins are arranged into six 8-bit ports: A, B, C, E, F, and G,
and one 6-bit port (D). Each of these seven ports serves a purpose other than I/O, de-
pending on the operating mode or peripheral functions selected. Note that ports B, C,
and F are available for I/O functions only in single-chip and bootstrap modes. The pins
of ports A, C, D, and G are fully bidirectional. Ports B and F are output-only ports. Port
E is an input-only port. Refer to Table 2-1 for details about the 54 port signals’ func-
tions within different operating modes.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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