cancel
Showing results for 
Search instead for 
Did you mean: 

Hyper Flash

4867226
New Contributor

 

 

hyperbus DQ wave is abnormal,why? Please help analyse。

circuit:

circuit.PNGDQ1-DQ6-Write.jpgDQ1-DQ6-REDA.jpg

0 Likes
7 Replies
AS_36
Moderator
Moderator

Hi

  • S26HS01GT datasheet mentions the recommended drive strength settings. Can you please confirm whether the setting is matching with your PCB trace impedance values?
  • Can you tell us what is the command for which the waveform has been captured?
  • Is the signal captured from the flash pins or from the microcontroller pins? If the signal is captured from microcontroller side, can you please try to capture from flash side?
  • Is it possible for you to provide the clock signal coming from the microcontroller as well?
  • Please go through the 'Decoupling Capacitors Recommendations' mentioned in this Application Note about HyperFlash™ and HyperRAM™ Layout Guide and make sure your design follows it.
  • We also recommend performing IBIS model simulations. Could you please tell me whether you have registered for the Semper Early Access Program or not? If you have not yet registered, you can go and register here. Once you have registered, you will have complete access to all Semper related documentation and models. After successful registration, you can get the IBIS model for S26HS01GT from this link.

 

Thank you and Regards.

0 Likes
4867226
New Contributor

hi

Thanks very much for replay.

We have sim, result is OK, drive strength setting is same as sim setting.

when read, the test point is SoC side, clk and DQ1 wave  as below.

readread

When write, the test point is flash side, clk an DQ2 wave as below. 

writewrite

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CLK is 196MHz.Wave(zoom) as below.

clk zoomclk zoom

SoC is CYT4DN(Cypress).

 

Best Regards.

 

0 Likes
Roy_Liu
Moderator
Moderator

1)     如果把频率降低( 80MHz 50MHz),波形有无改善?还是有~1V的半波吗?

If the frequency is reduced (such as 80MHz or 50MHz), is the waveform improved? Is there still a half wave of ~ 1V?

2)     请问flash在不操作的时候DQ的状态是floating的吗?对于写操作的这个图来说,当差分时钟不跳变时(主控对flash无操作)flash不会工作,此时为什么DQ线上会被拉高?另外在写的过程中flash不会输出只是被动输入要写的命令地址数据,但是此时主控的信号是~1V左右的半波,这个有些奇怪。

Is the state of DQ floating when flash is not in operation? For the graph of write operation, when the differential clock does not jump (the master control has no operation on the flash), the flash will not work. Why is the DQ line pulled up at this time? In addition, in the process of writing, flash will not output but passively input the command address data to be written, but at this time, the main control signal is about 1V half wave, which is strange.

Roy_Liu_0-1612407362783.jpeg

3)  对于读操作波形,也存在很多差分时钟不跳变时DQ依然为高电平的情况,会不会存在多个master同时访问同一slave的情况?这样可能会产生波形叠加及半波的可能性。

For the read operation waveform, there are many cases where DQ is still high when the differential clock does not jump. Will there be multiple masters accessing the same slave at the same time? This may result in the possibility of waveform superposition and half wave.

Roy_Liu_1-1612407387775.jpeg

 

Roy Liu
0 Likes
4867226
New Contributor

hi, Roy

1) 我正在尝试让软件帮忙修改,试看看。

2)不操作时,都是低电平。

       对的,就是奇怪。会不会跟flash或SOC误进入什么状态有关?

3)我们目前就是一对一。SoC 是CYT4DN(Cypress),有哪里需设置吗?

 

以上  谢谢。

0 Likes
Roy_Liu
Moderator
Moderator

Flash本身是Slave设备,全靠主控拉CSSCK+SCK#来进行操作,如果状态异常也是在读取状态寄存器时才会输出,目前来看至少对于写操作本身flash不会有任何输出动作。

这个问题是个例还是很多板都有问题?之前有成功读写过HyperFlash吗?只是修改配置之后不能访问还是始终都不能访问?上面Apurva发过一个HyperFlashlayout guide,里面提到了等线长等问题,不知道是否遵从了里面的一些规范?

另外,这个项目背景能不能大概介绍一下?

Roy Liu
0 Likes
4867226
New Contributor

hi, Roy

这批板都是这样的问题。

layout是按照guide来,等长和阻抗匹配50Ω都有遵守。

昨天有抓取了,write,SCK/#CS/DQ1/DS一开始的信号波形及局部扩大图。write:sck/#CS/DQ1/DSwrite:sck/#CS/DQ1/DSZOOM1ZOOM1ZOOM2ZOOM2

 

 

 

 

 

背景:

目前其实senmper flash这个功能,软件还没实现。

因为硬件要先检证,所以软件帮忙做了测试软件,如下:

Flash                     //  Launch Semper Flash mode.
Flash_EWR_Random          //      Flash Erase-Write-Read(verify) for random data
Flash_EWR_55              //      Flash Erase-Write-Read(verify) for all AA data
Flash_EWR_AA              //      Flash Erase-Write-Read(verify) for all 55 data
Flash_Erase               //      Comming soon!!
Flash_Write               //      Comming soon!!
Flash_Read                //      Comming soon!!

发一个简单命令,会有数据产生,这样抓取波形检证,这个时候发现的问题。

 

以上 谢谢。

 

0 Likes
AS_36
Moderator
Moderator

Hi,

  • Were you able to get rid of the half wave in your application? Since the half wave is present in the write and read operation both, we suspect it may be occurring due to some issue in the layout.
  • How many devices are showing this behavior? Are there any flash devices which are working fine?
  • Did you try to replace this flash device with another flash and check whether the issue persists?

Thank you. 

0 Likes