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Z8F082ASH020SC 参数 Datasheet PDF下载

Z8F082ASH020SC图片预览
型号: Z8F082ASH020SC
PDF下载: 下载PDF文件 查看货源
内容描述: Z8喝采XP -R F08xA系列与扩展外设 [Z8 Encore XP-R F08xA Series with eXtended Peripherals]
分类和应用: 微控制器和处理器外围集成电路光电二极管时钟
文件页数/大小: 244 页 / 2750 K
品牌: ZILOG [ ZILOG, INC. ]
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Z8 Encore! XP® F08xA Seriess  
Product Specification  
91  
devices on the multi-node network. The following three MULTIPROCESSOR modes are  
available in hardware:  
Interrupt on all address bytes  
Interrupt on matched address bytes and correctly framed data bytes  
Interrupt only on correctly framed data bytes  
These modes are selected with MPMD[1:0]in the UART Control 1 Register. For all mul-  
tiprocessor modes, bit MPENof the UART Control 1 Register must be set to 1.  
The first scheme is enabled by writing 01bto MPMD[1:0]. In this mode, all incoming  
address bytes cause an interrupt, while data bytes never cause an interrupt. The interrupt  
service routine must manually check the address byte that caused triggered the interrupt. If  
it matches the UART address, the software clears MPMD[0]. Each new incoming byte  
interrupts the CPU. The software is responsible for determining the end of the frame. It  
checks for the end-of-frame by reading the MPRXbit of the UART Status 1 Register for  
each incoming byte. If MPRX=1, a new frame has begun. If the address of this new frame  
is different from the UART’s address, MPMD[0] must be set to 1 causing the UART inter-  
rupts to go inactive until the next address byte. If the new frame’s address matches the  
UART’s, the data in the new frame is processed as well.  
The second scheme requires the following: set MPMD[1:0] to 10B and write the UART’s  
address into the UART Address Compare Register. This mode introduces additional hard-  
ware control, interrupting only on frames that match the UART’s address. When an  
incoming address byte does not match the UART’s address, it is ignored. All successive  
data bytes in this frame are also ignored. When a matching address byte occurs, an inter-  
rupt is issued and further interrupts now occur on each succesive data byte. When the first  
data byte in the frame is read, the NEWFRMbit of the UART Status 1 Register is asserted.  
All successive data bytes have NEWFRM=0. When the next address byte occurs, the hard-  
ware compares it to the UART’s address. If there is a match, the interrupts continues and  
the NEWFRMbit is set for the first byte of the new frame. If there is no match, the UART  
ignores all incoming bytes until the next address match.  
The third scheme is enabled by setting MPMD[1:0] to 11band by writing the UART’s  
address into the UART Address Compare Register. This mode is identical to the second  
scheme, except that there are no interrupts on address bytes. The first data byte of each  
frame remains accompanied by a NEWFRMassertion.  
External Driver Enable  
The UART provides a Driver Enable (DE) signal for off-chip bus transceivers. This fea-  
ture reduces the software overhead associated with using a GPIO pin to control the trans-  
ceiver when communicating on a multi-transceiver bus, such as RS-485.  
Driver Enable is an active High signal that envelopes the entire transmitted data frame  
including parity and Stop bits as illustrated in Figure 13. The Driver Enable signal asserts  
when a byte is written to the UART Transmit Data register. The Driver Enable signal  
PS024705-0405  
P R E L I M I N A R Y  
UART