24C512GP202与MCC v3.1.5和PLL的UARTx问题

大家好，我在MPLABX v3.45中使用MCC v3.1.5配置24EP512GP202（带有16MHz外部晶体）。我看到，如果设置：Primary OSC:16000000PLL:.soFosc=16000000，UART1可以正常工作。但是如果设置：Primary OSC:16000000PLL:enableconfiguring PLL以获得Fosc=140000000000，UART1将运行。错误的字符。在详细信息中，例如“TEST”，它打印“Txxx”，其中xxx是错误的符号。我还看到，配置PLL以获得较低的Fosc，例如Fosc=64000000，还正确地传输了第二符号……例如，它传输“TExx”而不是“TEST”。16000000或更低的传输字符都可以。我想有一个定时计算问题，对于PLL，对于外部晶体频率，增加Fosc变得越来越重要。我已经尝试使用不同的UARTx波特率（从2400到115200，但是它具有相同的行为w.我也尝试了以下两种传输方式：-用MCC启用“重定向打印到UARTx”并使用printf(“测试”)直接编写UARTx TX寄存器，但我总是得到相同的结果。



      以下为原文

    Hi all,
I'm configuring 24EP512GP202 (with 16MHz external crystal) using MCC v3.1.5 in MPLABX v3.45.
I saw that if I set:

Primary OSC: 16000000
PLL: disable

so Fosc = 16000000 the UART1 works properly.

but if I set:

Primary OSC: 16000000
PLL: enable

configuring PLL to obtain Fosc = 140000000, the UART1 prints out wrong chars. In the detail if I tx, for example, "TEST" it prints "Txxx" where xxx are wrong symbols.

I also saw that configuring PLL to obtain a lower Fosc, for example Fosc = 64000000, also the 2nd symbol is trasmitted properly...for example it trasmits "TExx" instead "TEST".

If I configure PLL to obtain Fosc = 16000000 or lower the trasmitted chars are all ok.

I suppose there is a timing calculation issue that becomes increasingly critical increasing Fosc with PLL respect to the external crystal frequecy.

I already tried to use different UARTx baud rate (from 2400 to 115200 but it has the same behaviour with all of them) and both using UART1 and UART2.
I also tried the following 2 ways to transmit:
- enabling "redirect printf to UARTx" with MCC and using printf("TEST")
- writing the UARTx TX register directly

but I had always the same result.

Thanks in advance,
Nicola