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MCP2515数据手册中的振荡器起振定时器（OST）值出错怎么解决？

嗨，我用的是MCP2515 CAN控制器，在125kHz可以从20MHz的CRATSTAR波特率。在数据表DS2000 1801H页55和59，它写道，振荡器启动时间（OST）被定义为128toSC。因为我运行在20MHz，我期待唤醒时间是6.4。而不是那样，我经历了一个大于1ms后发送唤醒命令。（ReqOP＝000在CuxTrl）是否可能是真正的ToSC值是128×TbAdRead，而不是128×Tosc？？？？有人经历过同样的行为吗？当做，

以上来自于百度翻译


      以下为原文

    Hi,

I'm using a MCP2515 CAN controller at 125kHz CAN baud rate from a 20MHz cristal.

In Datasheet DS20001801H-pages 55 and 59, it's written that the Oscillator Start-up time (OST) is defined as 128Tosc. Since I'm running at 20MHz, i'm expecting that the wakeup time is 6.4µs. Instead of that, I'm experiencing a OST greater than 1ms after sending the wakeup command. (REQOP = 000 in CANCTRL)

Is it possible that the real Tosc value is 128*TBaudRate instead of 128*Tosc???

Anybody experiencing the same behavioral?

Regards,
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赵文娜

2018-9-17 17:02:37
我刚才看到一个有趣的行为比较WaKIF中断有关晶体振荡。它似乎有两个阶段的唤醒。功率晶体，但不振荡（ChanSTAT= 0x24睡眠+ WAKIF）晶体振荡（ChanSTAT＝0x64侦听+WAKIF）正常模式（CANSTAT＝0x00正常）也许128个ToSC只在唤醒的第二阶段有效吗？？？？我希望这能帮助你帮助我！！！！当做，

以上来自于百度翻译


      以下为原文

    I just saw an interesting behavior when comparing the WAKIF interrupt related to the crystal oscillation. It seems to have two stage in Wake Up.

  • Power to crystal but not oscillating (CANSTAT = 0x24 Sleep + WAKIF)
  • Crystal oscillating (CANSTAT = 0x64 Listen Only + WAKIF)
  • Normal mode (CANSTAT = 0x00 Normal)
Maybe the 128 Tosc is only valid in the second stage of the wakeup???
 
I hope that will help you to help me!!!
 
Regards,
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赵文娜

2018-9-17 17:10:37
嗨，这是Microchip支持团队的第一个答案。我在等待更多的细节。---------------嗨，贾景晖，你好。你说得对。128ToSc适用于振荡器开始振荡的时刻。

以上来自于百度翻译


      以下为原文

    Hi,
Here is the first answer from the Microchip support team. I'm waiting for more details.
-------------------
Hi Marc, 
Good Day. 
You're right. The 128Tosc applies at the moment the oscillator starts oscillating. 
Regards, 
MJ
-------------------
Regards,
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蒋喜玲

2018-9-17 17:28:44
感谢您报告您的支持票的结果。对于一个20MHz的振荡器来说，毫秒似乎有点长——我本来期望几百微秒最大。什么连接到复位引脚？是否有一个可以解释延迟的RC复位电路？

以上来自于百度翻译


      以下为原文

    Thanks for reporting the results of your support ticket. A millisecond does seem a bit long for a 20MHz oscillator to get going - I would have expected a couple hundred microseconds max. What's connected to the Reset pin? Is there an RC reset circuit that could explain the delay?
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赵文娜

2018-9-17 17:36:06
谢谢你的回答，复位引脚直接连接到C的GPIO，当C准备就绪时它被强制高。在我的用例中，（总线活动唤醒中断），C已经准备好，模块永远不会复位（通过复位引脚或SPI复位命令EIDER）。

以上来自于百度翻译


      以下为原文

    Thank you mbrowning for your answer,
 
The reset pin is directly connected to a GPIO of the µC and it's forced high when the µC is ready.
 
In my use case, (Bus Activity Wake-up Interrupt), the µC is ready and the module is never reset (eider by the reset pin or by SPI reset command)
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