使用PIC18F47 K40I/MV的EUSAT奇异问题

Heloi最近遇到了一个奇怪的问题，我有一个通过EASART发送字符串的自定义函数，函数如下：ValeSerialWrrad（const char *x）{（*x）{easART1x编写（*x++）；}其中，EasART1x写是MPLAB的默认函数。问题是我能够。使用此功能在PIC18F47 K40浸印足迹，但不UQFN40足迹。（顺便说一下，我上传了完全相同的程序，在两个脚印，DIP工作，但不是另一个）我试图做SerialWrand（“Hello”）；在我的主程序，在我的笔记本电脑串口上看不到任何东西。然而，我发现我只能从UQFN40足迹中发送单个字符，例如EUARTAR1X写（'H'）；我还用示波器检查了TX线，当我使用UQFN40足迹的函数SyralWrad时，看不到任何下拉，但是看到了单字符信号。EUARTAR1X写的好。UART连接对于我的PCB上的DIP足迹芯片和UQFN40芯片来说是简单和相同的：PIC18F47 K40TX-& GT；MCP2221 RXPIC18F47 K40RX——& McP2221 TXONE概念，问题可能是什么？
                    
                    
               
                                                                                      以下为原文

                                                                            Hello

I have recently encountered a weird problem, I have a self-defined function for sending string through EUSART, function as follow:
void serialWrite(const char *x)
{
      while(*x)
      {
             EUSART1_Write(*x++);
       }
}

Where EUSART1_Write is the default function from mplab.

The problem is that I was able to use this function in PIC18F47k40 DIP footprint but not UQFN40 footprint. (By the way, I uploaded the exact same program in both footprint, DIP worked but not the other) Where I tried to do serialWrite("Hello"); in my main program and could not see anything on my laptop serial port. However I found out that I was only able to send out single character from the UQFN40 footprint, e.g. EUSART1_Write('H');.

I have also checked the TX line with oscilloscope, I could not see any pull down when I use the function serialWrite with UQFN40 footprint, but saw single character signal with EUSART1_Write alright.

The UART connection is simple and identical for the DIP footprint chip and UQFN40 chip on my PCB:
PIC18F47k40 Tx --> MCP2221 RX
PIC18F47k40 Rx --> MCP2221 TX

Any idea what the problem could be?