问题描述
我工作的一个项目，我需要用USB PHY芯片进行通信。我使用的是STM32 microcontoller。 （stm32f446ret6，的)
要在 USB PHY 芯片沟通，我需要使用 ULPI接口。这是一并行通信。此接口为60MHz的clockfrequenty。
我的 STM32控制器的频率是 180MHz的的（他的最大的，我查了一下这两次）。所以对于ULPI接口的每一个时钟脉冲，单片机有3个时钟脉冲。
要使用USB-PHY芯片的沟通，我需要首先让设备知道，巫寄存器我想调整。当USB-PHY芯片接收到该命令好，他会设置NXT行高。
我觉得这是我的问题。我需要检查或者这是高（offcourse使用if语句）。而这正是我的问题是，我想。难道if语句需要很多时钟周期？有没有办法解决这个问题？
我的code：
布尔UPLI_setRegister_FunctionControl（无效）
{ 如果（（GPIOA - ＆GT;＆IDR放大器; 0×01））{//检查DIR高
返回false;
}其他{
GPIOB - ＆GT; ODR = 4;
// INT J = 0; 如果（（GPIOA - ＆GT; IDR及（uint16_t）×0020））{//等到NXT控制线为高
GPIOB - ＆GT; ODR = 0b0000000001000000;
/ *
注册设置
LMP让 - ＆GT; 0
SuspendM - ＆GT; 1
复位 - ＆GT; 0
OPMODE - ＆GT; 00
TermSelect - ＆GT; 0
XcrvSelect - ＆GT; 00
* / 如果（GPIOA - ＆GT; IDR及（uint16_t）×0020）{
// NXT仍然很高
GPIOA - ＆GT; ODR | = 0×0002; // STP高
的for（int i = 0;我== 1;我++）; //浪费一些时间
//设置输出回0;
GPIOB - ＆GT; ODR = 0×0000;
GPIOA - ＆GT; ODR = 0×0000;
返回true;
}其他{
GPIOA - ＆GT; ODR | = 0×0002; // STP高
的for（int i = 0;我== 1;我++）; //浪费一些时间
GPIOB - ＆GT; ODR = 0x0000000;
GPIOA - ＆GT; ODR = 0x000000处;
返回false;
}
} 其他{
GPIOA - ＆GT; ODR | = 0×0002; // STP高
的for（int i = 0;我== 1;我++）; //浪费一些时间
GPIOB - ＆GT; ODR = 0x0000000;
GPIOA - ＆GT; ODR = 0x000000处;
返回false;
}
}}
您需要使用您的微控制器的USB_HS外设与此硬件交互，而不是它的GPIO。该GPIO都没有能力满足时序要求。
在硬件接口上的信息，在第35章（OTG_HS）提供的，以及从ST其他文档。
I'm working on a project where I need to communicate with an USB PHY chip. I am using a STM32 microcontoller. (stm32f446ret6, http://www.st.com/web/en/resource/technical/document/datasheet/DM00141306.pdf)
To communicate with the USB PHY chip, I need to use the ULPI interface. This is an parallel communication. This interface has a clockfrequenty of 60MHz.
The frequency of my STM32-controller is 180MHz(his maximum, I checked this twice). So for every clock pulse of the ULPI interface, the microcontroller had 3 clockpulses.
To communicate with the USB-PHY chip, I need first to let the device know, witch register I want to adjust. When the USB-PHY chip received this command good, he will set the NXT line high.
I think this is my problem. I need to check or this is high (offcourse with an if-statement). And that is where my problem is, I think. Is it possible that the if-statement takes to many clock-cycles? Is there a way to fix this problem?
My code:
bool UPLI_setRegister_FunctionControl(void)
{
if( (GPIOA -> IDR & 0x01)) {//check if the dir is high
return false;
} else {
GPIOB -> ODR = 4;
//int j =0;
if((GPIOA -> IDR & (uint16_t)0x0020)) { // wait until the nxt control line is high
GPIOB -> ODR = 0b0000000001000000;
/*
Register settings
LMP enable -> 0
SuspendM -> 1
Reset -> 0
Opmode -> 00
TermSelect -> 0
XcrvSelect -> 00
*/
if(GPIOA -> IDR & (uint16_t)0x0020) {
//NXT still high
GPIOA ->ODR |= 0x0002; //stp high
for(int i =0; i==1; i++); //waste some time
//set outputs back to 0;
GPIOB -> ODR = 0x0000;
GPIOA ->ODR = 0x0000;
return true;
} else {
GPIOA ->ODR |= 0x0002; //stp high
for(int i =0; i==1; i++); //waste some time
GPIOB -> ODR = 0x0000000;
GPIOA ->ODR = 0x000000;
return false;
}
}
else {
GPIOA ->ODR |= 0x0002; //stp high
for(int i =0; i==1; i++); //waste some time
GPIOB -> ODR = 0x0000000;
GPIOA ->ODR = 0x000000;
return false;
}
}
}
You need to use your microcontroller's USB_HS peripheral to interact with this hardware, not its GPIOs. The GPIOs will be incapable of meeting timing requirements.
Information on the hardware interface is available in chapter 35 ("OTG_HS") of the STM32F4 reference manual, as well as in other documentation from ST.
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