PIC18F I2C总线电容MSSP与Bit-Banging通信错误

PIC18F25K40，我公司使用的主要I2C通信是很差的选择/设计，几年后，我试图解决由于噪声问题导致的I2C通信错误，所以很有趣。我们不应该使用I2C进行板外通信，并且我们超过总线电容规格很多。我有很多硬件解决方案，但我的公司（很小）非常不愿意重新设计我们的硬件/通信。我尝试了主软件（TEMP）解决方案，当I2C线被锁上时，它复位（症状，而不是实际原因），但是我不能在嘈杂的Env中得到任何可靠的工作。熨斗。我决定将I2C转换为使用MSSP来敲击（在启动硬件更改之前耗尽所有的软件[TEMP]解决方案）。我只是在初始阶段，但我注意到总线电容很容易在规格内，现在我有点撞击I2C。使用相同的硬件设置（6FT电缆），我可以看到时钟线上的上升时间是122Ns，总线电容在108PF，与使用MSSP W相比。6FT电缆和相同的上拉电阻在1530pF，总线电容在1330pF。是否存在MSSP和BIT的母线电容差的原因？MSSP有内部过滤，这可能是原因吗？非常感谢您的任何建议或帮助。谢谢，Brad。



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    First time poster here;

Pic: PIC18f25k40

The main I2C communication my company uses was poorly selected/designed and years later I'm trying to fix I2C communication errors due to noise issues, so fun. We shouldn't be using I2C for off-board communication, and we exceed the bus capacitance spec by a lot. I have many hardware solutions, but my company (being small) is very reluctant for redesigning our hardware/communication.

I've attempted main software (temp) solutions for resetting the I2C lines when they get locked up (symptom, not actual cause) but I cant get anything reliable to work in noisy environments. I've decided to convert our I2C from using the MSSP to bit-banging (exhausting all my software [temp] solutions before we start hardware changes....) . I am only in the initial stages, but right away I noticed that the bus capacitance is easily within spec now that I'm bit-banging I2C.  Using the same hardware set-up (6ft cable), I can see that the raise time on the clocking lines is 122ns with bus capacitance at 108pF, compared to using the MSSP with 6ft cable and same pull-up resistors at 1.5us with bus capacitance at 1330pF.

Is there a reason for the bus capacitance difference between MSSP and Bit-banging? Is the MSSP have internal filtering that could be the reason for this? Any suggestions or help would be greatly appreciated.

Thanks,

Brad