RT1050 LPI2C问题

[haifeng_jin]

hi  在使用LPI2C的时候遇到一个问题，我下面的器件读一次是258个字节，但是目前LPI2C最大一次只能256字节，按照普通的I2C来说不应该有这种设置，比较奇怪目前的LPI2C，LPI2C_MasterReceive(EXAMPLE_I2C_MASTER, g_master_rxBuff, LPI2C_DATA_LENGTH);

RM手册上如下描述，上面说repeat的话可以从新读一次，但是下面的器件不能支持在发起一次start信号，这个LPI2C感觉挺奇怪。有什么办法解决吗？

MTDR寄存器：

[kerryzhou]

Hi haifeng jin ,

    楼主你好。

   你的意思是，你的从机超过256的部分，是需要重新发START还是不需要？

   如果需要，可以直接用CMD 100b,如果不需要，可以用000b。

   这个是可以灵活控制的。

   如果你还有问题，欢迎继续交流！

Have a great day,
Kerry

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[haifeng_jin]

hi 从机需要一次性读完258个字节，000b的话一次不是255个字节？

[kerryzhou]

hi haifeng,

   你RT1050是主机还是从机，从你描述像是主机，你从机是什么？

  从机一次读258个字节， 可以分两批读，第一批255，第二批剩下3字节，只要保证不发START，只发时钟和数据，从机就可以接着读下去。

  如果还有问题，欢迎继续交流。

Have a great day,
Kerry

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[haifeng_jin]

RT1050是主机，这样的话就是不发start，然后连续读两次，现在测试下来有问题，当I2C时钟高的时候，会漏掉后面的三个数据，我觉得LPI2C模块功能做的有点不合情理

[kerryzhou]

楼主你好！

你有没有用逻辑分析仪测试下I2C总线的波形？ 可以把你的i2c波形发出来我看看，尤其是问题的部分。

以及你测试的详细结果，这样便于我分析。

Have a great day,
Kerry

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[haifeng_jin]

hi Kerry：

        抓了数据，但是比较难找到，数据太多了，因为那个255字节后需要C语言执行以下在次读取的，但是这个时候clk正在发生，所以会导致执行C语言的时候，数据已经过了，所以最后几个字节就出错了，这个好像LPI2C没法解决的

[kerryzhou]

楼主你好！

是这样的，你那边有逻辑分析仪吗？通道深度调搞点，一般抓上千个byte都没有问题的，你可以debug下，然后只发258个字节出来，发之前进入trigger模式，这样一发送，就会抓取总线上所有的通信数据，而且你知道是最后几个字节，就能直接定位过去了。

抓到之后，把I2C波形分享给我，我仔细查看下。

Have a great day,
Kerry

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[haifeng_jin]

没搞定，感觉还是有风险，有IO模拟了IIC

[kerryzhou]

感谢你的信息更新。

没搞定，是遇到什么具体问题了呢？

现在问题比较多，所以没有太多时间测试，后面我有时间的时候，也会去测测你这个问题。

Have a great day,
Kerry

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