Why delay is different?

[li kai]

Posted on March 20, 2017 at 15:23

First, to do a show, the green line is SPI_DIN,the red is PG6, the blue is PA2, the yellow is trigger.When we make a 

 data acquisition system, we use the stm32f405zgt6 as mcu and ADS131E08 as analog-digital converter. In the project, we use the SPI2 to transmit data via DMA1, use FSMC to control the external SRAM. During the practice, we found that there is a abnormal point after 

some interval

of

time

, which is not constant. Using the

leCroy oscilloscope catch the abnormal CS signal liker the blue line. After that, configure the PG6(GPIOG,GPIO_Pin_6), which have the same 

configuration compared to PA2(GPIOA,GPIO_Pin_2). But from the figure we can find the two signals are distinct. The red is normal which is we want to be and the blue one is not.

[li kai]

Posted on March 20, 2017 at 15:41

First, to do a show, the green line is SPI_DIN,the red is PG6, the blue is PA2, the yellow is trigger.When we make a 

 data acquisition system, we use the stm32f405zgt6 as MCU and ADS131E08 as analog-digital converter. In the project, we use the SPI2 to transmit data via DMA1, use FSMC to control the external SRAM. During the practice, we found that there is a abnormal point after 

some interval

of

time

, which is not constant. Using the

leCroy oscilloscope catch the abnormal CS signal liker the blue line. After that, configure the PG6(GPIOG,GPIO_Pin_6), which have the same 

configuration compared to PA2(GPIOA,GPIO_Pin_2). But from the figure we can find the two signals are distinct. The red is normal which is we want to be and the blue one is not. It is certain that we do not reuse the PA2 in other parts of program. I want to know the possibilities to lead the phenomenon. This phenomenon is same with the chapter 2.1.10 in STM32F40x and STM32F41x Errata sheet? I am looking forward your reply. If your have some good idea for me, 

I will be eternally grateful. My Wechat number is 15108305872, and my mail is

mailto:likaitoturing@163.com

. At last i want to say i am a die-hard fans of STM32 series products.

[li kai]

Posted on March 21, 2017 at 15:18

First, to do a show, the green line is SPI_DIN,the red is PG6, the blue is PA2, the yellow is trigger.When we make a 

 data acquisition system, we use the stm32f405zgt6 as MCU and ADS131E08 as analog-digital converter. In the project, we use the SPI2 to transmit data via DMA1, use FSMC to control the external SRAM. During the practice, we found that there is a abnormal point after 

some interval

of

time

, which is not constant. Using the

leCroy oscilloscope catch the abnormal CS signal liker the blue line. After that, configure the PG6(GPIOG,GPIO_Pin_6), which have the same 

configuration compared to PA2(GPIOA,GPIO_Pin_2). But from the figure we can find the two signals are distinct. The red is normal which is we want to be and the blue one is not. It is certain that we do not reuse the PA2 in other parts of program. I want to know the possibilities to lead the phenomenon. This phenomenon is same with the chapter 2.1.10 in STM32F40x and STM32F41x Errata sheet? I am looking forward your reply. If your have some good idea for me, 

I will be eternally grateful. My Wechat number is 15108305872, and my mail is

mailto:likaitoturing@163.com

. At last i want to say i am a 

die-hard fans of STM32 series products.

[Chris1]

Posted on March 21, 2017 at 19:42

What is driving PA2?

[Tesla DeLorean]

Posted on March 22, 2017 at 00:46

Hard to say, this definitely needs the code to understand what is supposed to be happening. Assuming the expectation that the SPI is driving the CS signal, but really don't think the SPI peripheral works like that (ie doesn't assert -CS byte-to-byte)

Or is the CS an FSMC signal, really not sufficiently clear.