如何用pic16f145x通用IO引脚模拟I2c

在我的应用程序中，我计划使用通用的Io管脚来模拟i2c……与我的i2c芯片（如PCF8574、ADS7828）通信……我已经成功地在一些C51系列单片机上实现了i2c，但我相信在微芯片上会有所不同，或者基本上，在PIC16F上可以做到吗？它将达到的最大速度是多少？对于I2c总线，我们需要io管脚作为开路漏极输出，但是在PIC16F上似乎不可能。但是我相信我们可以通过控制Io管脚的输入/输出方向来实现这一点：如果我们将管脚配置成输入，那么实际上在管脚输出上会出现高电平的输出，因为我们有定义为上拉电阻器的上拉电阻。根据I2c规范，如果我们想把引脚设置为低输出，我们可以把引脚设置为输出，写0，这是安全的，因为我们有上拉电阻。但是，如果我们把这个PIC的引脚设置为输出，写1，会发生什么呢？如果I2C芯片对应引脚设置为0，是否危险？在这种情况下，VCC将直接引导到地面？？！如果有人能给出一些示例代码，那将是很大的帮助，谢谢！



      以下为原文

    In my application,i'm planning to use general Io pins to simulate i2c...to communicate with my i2c chips like PCF8574,or ADS7828...;
i've implemented i2c on some C51 series mcu successfully,but i believe it would be different on microchip,or basically,is it possible to do it on PIC16F? what is the max speed it will reach at?
for I2c bus,we need io pins to act as open drain outputs,but seems impossible on PIC16F.
but i believe we could do it by controlling Io pins input/output directions:if we configure the pin as input,actually high level ouput will appear on the pin's out ,since we have pull-up resistors which is defined by I2c spec;if we want to set pin to low output,we can set ths pin as output,and write 0,it is safe because we have pull up resistor.
but what will happen if we set this PIC's pin as output,and write 1? is it dangerious if i2c chips corresponding pin setting to 0?under this situation,the VCC will direct led to ground??!
it will be great help if anyone could give some example code,thanks in advance!
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