根据datasheet 见图1上面说的,XT1 外接的是32.768K的晶振,XT2接的是8M的晶振。 测试晶振是否起振用的是官网的例程,如下:
// MSP-FET430P430 Demo - FLL+, Output 32kHz Xtal + HF Xtal + Internal DCO
//
// Description: This program demonstrates using an external 32kHz crystal to
// supply ACLK, and using a high speed crystal or resonator to supply SMCLK.
// MLCK for the CPU is supplied by the internal DCO. The 32kHz crystal
// connects between pins Xin and Xout. The high frequency crystal or
// resonator connects between pins XT2IN and XT2OUT. The DCO clock is
// generated internally and calibrated from the 32kHz crystal. ACLK is
// brought out on pin P1.5, SMCLK is brought out on P1.4, and MCLK is
// brought out on pin P1.1.
// ACLK = LFXT1 = 32768Hz, MCLK = SMCLK = default DCO = 32 x ACLK = 1048576Hz
// //* An external watch crystal between XIN & XOUT is required for ACLK *//
//
// NOTE: External matching capacitors must be added for the high
// speed crystal or resonator as required.
//
// MSP430F449
// -----------------
// /| | XIN|-
// | | | 32kHz
// ---|RST XOUT|-
// | |
// | |
// | XT2IN|-
// | | HF XTAL or Resonator (add capacitors)
// | XT2OUT|-
// | |
// | P1.5|--> ACLK = 32kHz Crystal Out
// | |
// | P1.4|--> SMCLK = High Freq Xtal or Resonator Out
// | |
// | P1.1|--> MCLK = Default DCO Frequency
// | |
// | |
//
// G. Morton
// Texas Instruments Inc.
// Feb 2005
// Built with CCE Version: 3.2.0 and IAR Embedded Workbench Version: 3.21A
//*****************************************************************************
#include <msp430x43x.h>
void main(void)
{
unsigned int i;
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
FLL_CTL0 |= XCAP18PF; // Set load capacitance
FLL_CTL1 &= ~XT2OFF; // Turn on XT2
// Loop until 32kHz crystal stabilizes
do
{
IFG1 &= ~OFIFG; // Clear oscillator fault flag
for (i = 50000; i; i--); // Delay
}
while (IFG1 & OFIFG); // Test osc fault flag
FLL_CTL1 = SELS; // Select SMCLK source as XT2CLK
P1DIR = 0x32; // Set P1.1,4,5 as outputs
P1SEL = 0x32; // Select P1.1,4,5 as clocks
while(1); // Loop in place
}
但是晶振一直不起振,我用内部的DCO就可以实现需要实现的功能,实在是无法解决了,希望大家帮忙解决下!
经过实际测试发现JTAG口的TD0、TD1、TMS 却出来的是8M的晶振。上传我自己画的原理图见图2
,板子是我自己焊的!
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