MSP430-I2C 硬件模块的时钟设置问题

Hi zheng,

  应该是你对UCB1CTL0和UCB1CTL1两个寄存器赋值的操作有问题，试着按下面的格式改一下试试：

UCB0CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB0CTL1 = UCSSEL_1 + UCSWRST; 

谢谢

ken

谢谢您的答复，我修改为以下设置了，单结果没有变化。

UCB1CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB1CTL1 = UCSSEL_1 + UCSWRST; 

谢谢您的回复，我修改为以下设置了，单结果没有改变。

UCB1CTL0 = UCMST + UCMODE_3 + UCSYNC; // I2C Master, synchronous mode
UCB1CTL1 = UCSSEL_1 + UCSWRST; 

Hi Zheng,

  你的系统能正常工作了吗？I2C有没有建立通信呢？同时在硬件上面I2C总线的SCL和SDA两个管脚有没有才去电阻上拉的操作？

谢谢

ken

Hi zheng，

   另外由于PIN8.5和PIN8.6是多功能复合的管脚，针对他们的功能选择寄存器，你是怎么配置的呢？有没有正确的配置？

谢谢

ken

谢谢您回复，我的系统能正常工作，SPI和UART的功能都能正常运行。

现在只是I2C无法建立通信，因为tmp112需要的时钟至少是1Khz。

在硬件上面I2C总线的SCL和SDA两个管脚的电压为3.3v，没有问题。

您好，端口是这样设置的

GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P8,GPIO_PIN5 + GPIO_PIN6);

这个应该也没有问题，我用这个方法设置的SPI和UART都能正常工作。

Hi zheng，

  不好意思，问一下。你描述的这个函数是自己定义的吗？以前没有用到类似的函数，想请教一下。

能看一下这个函数具体的定义吗？

谢谢

ken

您好，这个函数用的是TI的Drivelib，定义是：

void GPIO_setAsPeripheralModuleFunctionInputPin(
uint8_t selectedPort,
uint16_t selectedPins
)
{
assert((GPIO_PORT_P1 == selectedPort) || (GPIO_PORT_P2 == selectedPort) ||
(GPIO_PORT_P3 == selectedPort) || (GPIO_PORT_P4 == selectedPort) ||
(GPIO_PORT_P5 == selectedPort) || (GPIO_PORT_P6 == selectedPort) ||
(GPIO_PORT_P7 == selectedPort) || (GPIO_PORT_P8 == selectedPort) ||
(GPIO_PORT_P9 == selectedPort) || (GPIO_PORT_P10 == selectedPort) ||
(GPIO_PORT_P11 == selectedPort) || (GPIO_PORT_PA == selectedPort) ||
(GPIO_PORT_PB == selectedPort) || (GPIO_PORT_PC == selectedPort) ||
(GPIO_PORT_PD == selectedPort) || (GPIO_PORT_PE == selectedPort) ||
(GPIO_PORT_PF == selectedPort) || (GPIO_PORT_PJ == selectedPort)
);

assert(0x00 != (selectedPins & (GPIO_PIN0 + GPIO_PIN1 + GPIO_PIN2 +
GPIO_PIN3 + GPIO_PIN4 + GPIO_PIN5 +
GPIO_PIN6 + GPIO_PIN7 + GPIO_PIN8 +
GPIO_PIN9 + GPIO_PIN10 + GPIO_PIN11 +
GPIO_PIN12 + GPIO_PIN13 + GPIO_PIN14 +
GPIO_PIN15
)));

uint32_t baseAddress = privateGPIOGetBaseAddress(selectedPort);

assert((0xFFFF != baseAddress) );
if (0xFFFF == baseAddress)
return;

switch (selectedPort) {
case GPIO_PORT_P1:
case GPIO_PORT_P3:
case GPIO_PORT_P5:
case GPIO_PORT_P7:
case GPIO_PORT_P9:
HWREG8(baseAddress + OFS_P1SEL) |= (uint8_t)selectedPins;
HWREG8(baseAddress + OFS_P1DIR) &= (uint8_t) ~selectedPins;
break;
case GPIO_PORT_P2:
case GPIO_PORT_P4:
case GPIO_PORT_P6:
case GPIO_PORT_P8:
case GPIO_PORT_P10:
HWREG8(baseAddress + OFS_P2SEL) |= (uint8_t)selectedPins;
HWREG8(baseAddress + OFS_P2DIR) &= (uint8_t) ~selectedPins;
break;
case GPIO_PORT_PA:
case GPIO_PORT_PB:
case GPIO_PORT_PC:
case GPIO_PORT_PD:
case GPIO_PORT_PE:
case GPIO_PORT_PF:
case GPIO_PORT_PJ:
case GPIO_PORT_P11:
HWREG16(baseAddress + OFS_PASEL) |= selectedPins;
HWREG16(baseAddress + OFS_PADIR) &= ~selectedPins;
break;
}
}

Hi zheng，

  谢谢你的信息，它的作用和设置P6DIR + P8SEL是一样的。(P8SEL = 0x60; P8DIR = 0x60)

如果都是这样的话，这在软件配置方面，应该是没有问题的啊。因为我们的实例代码就是这样测试的。

其余的只能是检查I2C的硬件连接了，如果SDA和SCL上面都有上拉电阻的话，整个通信应该是能正常工作。

谢谢

ken

谢谢您的回复，我用了TI的例程msp430f665x_uscib0_i2c_07试了试，发现结果没有变化。

您看看还有什么原因能影响I2C时钟频率呢。

Hi zheng，

   现在感觉还真没什么办法测了。要不你试试用芯片上的另外一组IIC的接口来通信看看。试着排除一下芯片功能的问题。

谢谢

ken

你好,

IIC时钟是1HZ是不可能的，你有尝试把ACK做输出看其频率是否是32768HZ吗?

你是如何测量IIC时钟频率的，写一帧数据然后测量CLK周期？

可以把你的波形贴出来吗？SDA和SLK的。

您好，谢谢您的回复。

ACLK输出32768HZ我测量过没有问题，

我把IIC的波形发给您看看。。

SDA是CH2，SLC是CH1.

谢谢您的回复。

ACK输出是32768HZ，我用示波器确认了。

我把I2C的波形发给您看看。

CH1是SLK，CH2是SDA。。

你好，

你截图的是IIC寻地址的波形吗?

可能是带宽不够的原因，我看你一帧完整波形没有截取下来，我本来打算看一下ACK回复信号和一帧完整的寻地址波形。

1.出现你这个原因我有点疑惑，在用SMCLK作为IIC时钟源的时候，能不能尝试改变一下波特率设置寄存器的值，我看你给的是1，改UCBxBR0的值。看输出是否还是16HZ。

2.检查是不是其他硬件模块,SPI,UART和IIC共用了同一个模块？可能性比较小

3.GPIO设置问题，能否尝试一下，单独写一个测试用例，用drive lib测试IIC模块，其他东西我都不加，用于诊断问题点。

测试代码如下，或者你在drive lib里面找：

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#include "inc/hw_memmap.h"
#include "usci_b_i2c.h"
#include "ucs.h"
#include "wdt_a.h"
#include "gpio.h"

//*****************************************************************************
//! This example shows how to configure the I2C module as a master for
//! single byte reception in interrupt driven mode. The address of the slave
//! module that the master is communicating with also set in this example.
//!
//! This example uses the following peripherals and I/O signals. You must
//! review these and change as needed for your own board:
//! - I2C peripheral
//! - GPIO Port peripheral (for I2C pins)
//! - SCL2
//! - SDA
//!
//! This example uses the following interrupt handlers. To use this example
//! in your own application you must add these interrupt handlers to your
//! vector table.
//! - USCI_B0_VECTOR.
//!
//
//*****************************************************************************
//*****************************************************************************
//
//Set the address for slave module. This is a 7-bit address sent in the
//following format:
//[A6:A5:A4:A3:A2:A1:A0:RS]
//
//A zero in the "RS" position of the first byte means that the master
//transmits (sends) data to the selected slave, and a one in this position
//means that the master receives data from the slave.
//
//*****************************************************************************
#define SLAVE_ADDRESS 0x48

uint8_t receivedData;

void main (void)
{
//Stop WDT
WDT_A_hold(WDT_A_BASE);

//Assign I2C pins to USCI_B0
GPIO_setAsPeripheralModuleFunctionInputPin(
GPIO_PORT_P3,
GPIO_PIN0 + GPIO_PIN1
);

//Initialize Master
USCI_B_I2C_masterInit(USCI_B0_BASE,
USCI_B_I2C_CLOCKSOURCE_SMCLK,
UCS_getSMCLK(UCS_BASE),
USCI_B_I2C_SET_DATA_RATE_400KBPS
);

//Specify slave address
USCI_B_I2C_setSlaveAddress(USCI_B0_BASE,
SLAVE_ADDRESS
);

//Set Master in receive mode
USCI_B_I2C_setMode(USCI_B0_BASE,
USCI_B_I2C_RECEIVE_MODE
);

//Enable I2C Module to start operations
USCI_B_I2C_enable(USCI_B0_BASE);

//Enable master Receive interrupt
USCI_B_I2C_clearInterruptFlag(USCI_B0_BASE,
USCI_B_I2C_RECEIVE_INTERRUPT
);
USCI_B_I2C_enableInterrupt(USCI_B0_BASE,
USCI_B_I2C_RECEIVE_INTERRUPT
);

while (1)
{
//Initiate command to receive a single character from Slave
USCI_B_I2C_masterSingleReceiveStart(USCI_B0_BASE);

//Enter low power mode 0 with interrupts enabled.
//Wait until character is received.
__bis_SR_register(LPM0_bits + GIE);
__no_operation();
}
}

//******************************************************************************
//
//This is the USCI_B0 interrupt vector service routine.
//
//******************************************************************************
#pragma vector = USCI_B0_VECTOR
__interrupt void USCI_B0_ISR (void)
{
switch (__even_in_range(UCB0IV,12)){
//Vector 10: Data received - RXIFG
case USCI_I2C_UCRXIFG:
{
//Grab data from data register
receivedData = USCI_B_I2C_masterSingleReceive(
USCI_B0_BASE);

//Exit low power mode 0 and disable GIE on interrupt exit
__bic_SR_register_on_exit(LPM0_bits + GIE);

break;
}

default: break;
}
}

出差回来，看到您的回复，谢谢您。

>1.出现你这个原因我有点疑惑，在用SMCLK作为IIC时钟源的时候，能不能尝试改变一下波特率设置寄存器的值，我看你给的是1，改UCBxBR0的值。看输出是否还是>16HZ。

我把UCBxBR0改成其他值（例如2），结果不出波形了。

还有我用ACLK作时钟源后结果输出波形为0.5Hz

>2.检查是不是其他硬件模块,SPI,UART和IIC共用了同一个模块？可能性比较小

我用CCS的例程做的测试，这块应该不会有问题。

>3.GPIO设置问题，能否尝试一下，单独写一个测试用例，用drive lib测试IIC模块，其他东西我都不加，用于诊断问题点。

这个我试过了输出为USCI_B0的端口了，但是没有波形。程序卡死在

USCI_B_I2C_masterSingleReceive(
USCI_B0_BASE);函数里的

//Poll for transmit interrupt flag.
while (!(HWREG8(baseAddress + OFS_UCBxIFG) & UCTXIFG)) ;