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參數資料
| 型號： | W77IE58 |
| 廠商： | WINBOND ELECTRONICS CORP |
| 元件分類： | 微控制器/微處理器 |
| 英文描述： | 8-BIT MICROCONTROLLER |
| 中文描述： | 8-BIT, FLASH, 25 MHz, MICROCONTROLLER, PDIP40 |
| 封裝： | DIP-40 |
| 文件頁數： | 74/90頁 |
| 文件大小： | 409K |
| 代理商： | W77IE58 |
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Preliminary W77IE58
- 74 -
Framing Error Detection
A Frame Error occurs when a valid stop bit is not detected. This could indicate incorrect serial data
communication. Typically the frame error is due to noise and contention on the serial communication
line. The W77IE58 has the facility to detect such framing errors and set a flag which can be checked by
software.
The Frame Error FE(FE_1) bit is located in SCON.7(SCON1.7). This bit is normally used as SM0 in the
standard 8051 family. However, in the W77IE58 it serves a dual function and is called SM0/FE
(SM0_1/FE_1). There are actually two separate flags, one for SM0 and the other for FE. The flag that is
actually accessed as SCON.7(SCON1.7) is determined by SMOD0 (PCON.6) bit. When SMOD0 is set
to 1, then the FE flag is indicated in SM0/FE. When SMOD0 is set to 0, then the SM0 flag is indicated
in SM0/FE.
The FE bit is set to 1 by hardware but must be cleared by software. Note that SMOD0 must be 1 while
reading or writing to FE or FE_1. If FE is set, then any following frames received without any error will not
clear the FE flag. The clearing has to be done by software.
Multiprocessor Communications
Multiprocessor communications makes use of the 9th data bit in modes 2 and 3. In the W77IE58, the RI
flag is set only if the received byte corresponds to the Given or Broadcast address. This hardware feature
eliminates the software overhead required in checking every received address, and greatly simplifies the
software programmer task.
In the multiprocessor communication mode, the address bytes are distinguished from the data bytes by
transmitting the address with the 9th bit set high. When the master processor wants to transmit a block
of data to one of the slaves, it first sends out the address of the targeted slave (or slaves). All the slave
processors should have their SM2 bit set high when waiting for an address byte. This ensures that they
will be interrupted only by the reception of a address byte. The Automatic address recognition feature
ensures that only the addressed slave will be interrupted. The address comparison is done in hardware
not software.
The addressed slave clears the SM2 bit, thereby clearing the way to receive data bytes. With SM2 = 0,
the slave will be interrupted on the reception of every single complete frame of data. The unaddressed
slaves will be unaffected, as they will be still waiting for their address. In Mode 1, the 9th bit is the stop
bit, which is 1 in case of a valid frame. If SM2 is 1, then RI is set only if a valid frame is received and the
received byte matches the Given or Broadcast address.
The Master processor can selectively communicate with groups of slaves by using the Given Address.
All the slaves can be addressed together using the Broadcast Address. The addresses for each slave
are defined by the SADDR and SADEN SFRs. The slave address is an 8bit value specified in the
SADDR SFR. The SADEN SFR is actually a mask for the byte value in SADDR. If a bit position in
SADEN is 0, then the corresponding bit position in SADDR is don't care. Only those bit positions in
SADDR whose corresponding bits in SADEN are 1 are used to obtain the Given Address. This gives the
user flexibility to address multiple slaves without changing the slave address in SADDR.
The following example shows how the user can define the Given Address to address different slaves.
Slave 1:
SADDR 1010 0100
SADEN 1111 1010
Given
1010 0x0x
相關PDF資料 |
PDF描述 |
|---|---|
| W77L32 | 8-BIT MICROCONTROLLER |
| W77LE532 | 8 BIT MICROCONTROLLER |
| W77LE58 | 8 BIT MICROCONTROLLER |
| W77LE58-25 | 8 BIT MICROCONTROLLER |
| W77LE58F-25 | 8 BIT MICROCONTROLLER |
相關代理商/技術參數 |
參數描述 |
|---|---|
| W77IE58_06 | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
| W77J_1G WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| W77J_2GST WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| W77J_3G WAF | 制造商:Fairchild Semiconductor Corporation 功能描述: |
| W77L032A | 制造商:WINBOND 制造商全稱:Winbond 功能描述:8-BIT MICROCONTROLLER |
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