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嗨，在数据表中有MCLR连接的例子。有一个电容器和两个电阻器连接到这个引脚。电容器必须通过跳线连接（当程序员连接时需要断开它）。在这个板上没有电容器连接到MCLR引脚，但是有嵌入式调试器。我的问题是：我用这个微控制器设计我的板。是否需要在我的板上使用这个电容器，哪里没有嵌入式调试器？
以上来自于百度翻译 以下为原文 Hi, In datasheet there is example of MCLR connection. There are a capacitor and two resistors connected to this pin. A capacitor must be connected via a jumper (there is need to disconnect it when programmer is connected). I have MPLAB Starter Kit for Digital Power (DM330017-2). On this board there is no capacitor connected to MCLR pin but there is embedded debugger. My question is: I'm designing my board with this microcontroller. Is it necessary to use this capacitor on my board, where is no embedded debugger? 
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8个回答
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MCLR的电容器有助于提高电磁抗扰度。如果您没有遇到任何有关EMI的问题，就不需要提供电容器。OTHH，如果需要电容器，请确保在调试器/编程工具访问期间可以断开它。（哦，是的，当调试器或程序员连接时，可能需要断开连接，但这取决于单个工具RESP。它有一个集成的调试器，它将（最有可能）主动地驱动MCLR。因此，不需要电容器（因为它不能比调试程序的活动驱动器更有效地提高EMI）。希望这有帮助。
以上来自于百度翻译 以下为原文 A capacitor at MCLR may help to improve EM immunity. If you do not experience any issues regarding EMI, there is no need to provide a capacitor. OTOH, if you need a capacitor, make sure you can disconnect it during debugger/programming tool access. (Oh yes - there might be a need to disconnect it when a debugger or programmer is attached, But this depends on the individual tool resp. its timing.) Where there is an integrated debugger, this will (most likely) drive MCLR all the time actively. Thus there is no need for a capacitor (as this cannot improve EMI more than the active drive from the debugger). Hope this helps |
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此外，电阻器/电容器组合用于在短时间内保持MMCRPIN低，使得电源在MCU开始工作之前可以变得稳定。没有电容器（即只是一个上拉电阻），MCU可以从VCC线路开始仍然有点低（或者随着PSU稳定等振荡），这可能导致MCU启动、复位、重新启动并最终开始。确切地说，这有什么影响取决于你的代码在开始广告上的正确性，在重置之前执行多少。当然这只是一个关于加电的问题。稍后的重置（使用MCLR 线）将使VCC线稳定（或者可以假设）。
以上来自于百度翻译 以下为原文 Also the resistor/capacitor combination is used to hold the MCLR pin low for a short time so that the power supply can become stable before the MCU starts to operate. Without the capacitor (i.e. just a pull-up resistor) the MCU can start with the Vcc line still a little low (or oscillating as the PSU stabilises etc.) which may cause the MCU to start, reset, start again and finally get going. Exactly what effect this has depends on what you code does right at the start ad how much gets executed before the reset. Of course this is only an issue on power-up - later resets (using the MCLR line) will have the Vcc lines stable (or so one can assume). Susan |
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这假设上电复位延迟和BOR不活跃。CAP仅在有限数量的应用中才需要。如果你不确定，把它放在黑板上，不要填充它。
以上来自于百度翻译 以下为原文 This assumes the Power on reset delay and BOR are not active. The cap is only needed in a limited number of applications. If you are not sure put it on the Board and do not populate it. |
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@澳元SUSAN与所有的POR/BOR片上电路，您可以轻松地生活没有/MCLR。这是对“好时光”的回忆。我曾经决定不使用这个输入来在启动过程中获得一些时间优势。这导致了一些“挑战”（部分芯片外周边有不同的最低电压要求），但最终我们得到了一个优越的系统，付出了努力。
以上来自于百度翻译 以下为原文 @ Aussie Susan With all that POR / BOR on-chip circuitry you can easily live without /MCLR. This is some reminiscence to the 'good old times'. I once decided against using this input to gain some timing advantage during startup. This caused a number of "challenges" (part of the off-chip peripherals had differing minimum-voltages requirements), but in the end we got a superior system and the efforts paid out. |
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谢谢你的回答。在我的申请中不需要快速启动，但是有一个高噪音的环境。由于EMI，我会把这个电容放在我的板上。
以上来自于百度翻译 以下为原文 Thanks for answers. In my application there is no need for a quick start, but there is a high noise environment. I will put this capacitor on my board due to EMI. |
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我做一些相当可怕的电磁干扰，我从来没有把电容器上的MCLR线，除非董事会是单面的。曾经在PIC16C的单面板上有一个闩锁问题…微控制器埋在RF感应加热器逆变器内部，用该方法进行分选。如果你不确定的话，我会随身带着垫，如果你不确定的话，我就可以在5V和3.3V的UC上离开。
以上来自于百度翻译 以下为原文 I make some pretty horrible EMI and I've never had to put a capacitor on the MCLR line, unless the board is single sided. Once had a bit of a latch up problem on a single sided board with pic16c... microcontroller buried deep inside a RF induction heater inverter floating on the mains that was sorted by that method . Would go with the putting the pads down and leaving unpopulated if you are not sure, but I've always got away with it on 5V and 3.3V uC's. |
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谢谢你提供的信息。顺便说一句：我的应用也是一个感应加热器。
以上来自于百度翻译 以下为原文 Thanks for the info. BTW: My application is also an induction heater. |
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