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修改时间 04-14-2017 06:33 PM
04-16-2017 11:04 AM - 编辑日期 04-16-2017 11:16 AM
修改时间 04-17-2017 09:28 AM
1.从我提供的图片，可以看到SMBus SDA、SCL信号已经通Crossbar分配到 P1.2 和 P2.0上了。
3.我们知道P2.0同时也是C2D，与C2编程接口的数据线复用。并现在的问题是同样的程序，只是将SMBus SDA、SCL信号通Crossbar分别配到的引脚不同，分配到其它引脚上通信没有问题，但是分配到P1.2 和 P2.0引脚上就有问题，并且程序都是烧录到MCU后，拔掉Debug线后观察程序现象的。
04-19-2017 12:33 PM - 编辑日期 04-19-2017 02:24 PM
We only suggest to put a pullup resistor on C2CK pin.
But I did not heard of the issue that C2 will be broken when adding a pullup on C2D. But please follow the suggestion from FAE, the C2 should work without external pull-up on C2D.
My views are my own and do not necessarily represent the views of Silicon Labs
修改时间 04-19-2017 02:39 PM
I corrected the previous post. "I did not heard of any issue to use the external pullup resistor on C2D".
if you use the GPIO as pushpull (output), usually you don't need the external pullup circuit. But I don't think the external pullup will damage the GPIO with a 100k ohm resistor.
If you use the GPIO as open drain or digital input, there is an internal weak pullup you could enabled. there is no problem for the MCU to detect the input level. an external pullup will help to support higher speed (rising time of the open drain mode). for example if you use the open drain mode for the SMBus/I2C, we suggest you use an external pull up because sometimes the internal pullup is a little weak.
Maybe below KB helps: