the wifi board based on *** module (based on CYW43340 ) can not scan any SSID

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daniel_qian1991
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Hi gays

There is a random problems (about 2% percent ) that the wifi board can not scan any SSID in the mass production.Now ,based on the phenomenon,three expericements are conducted.

Step 1,  i make non-signaling RF test for the "fail" board  and the results is OK compared to the datasheet of module manufacturer(based on CYW43340) ,and so it  is proved to be OK for the hardware with the wifi bord.

Step 2, strangely, when i exchange the ***module(based on CYW43340)  between PASS board and FAIL board,the phenomenon can not scan any SSID is bond with the *** module,not the board.The result seems to be proved the opposite conclusion with the step1.Namely,the module(based on CYW43340) is damaged.

Step3, i take the module(based on CYW43340) from the  FAIL board into the producre of testing  with module, and the producre consists of two parts including load the wifi firmware and scan the SSID,Finally ,the result makes me feel confused because of the module(based on CYW43340) of the  FAIL board can pass the  producre of test.

So,i can not get a conclusion if the wifi board is OK or damaged.Please give me helpful advice to shot on the strange problem,tks.

Best wishes for you!

 

PS: the wifi board consists of ***  module and the module includes CYW43340,   **** indicates a the manufacturer of module based on CYW43340.

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Zhengbao_Zhang
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建议这样做:

1.  有问题的板子用非信令扫一遍,看是否有频偏,EVM啥的是否临界, 我记得EVM和频偏都会影响到scan。

2. 如果第一步没有问题,  可以考虑拿夹具和你们产线的转接板到同一环境下做对比, 只有一致的环境才能说明问题。

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Zhengbao_Zhang
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Hello:

First one:

the phenomenon can not scan any SSID is bond with the *** module , Do you mean the failed issue is following the module which is tested failed in production line, not in the big board in production line. 

And the fail is  "signaling RF test"  , but non-signal test is correct . 

Second one:

   Even the board failed in RF test in first stage , it can scan the ssid also , is that right ?

I think you can get the signal test results from the failed module and have a compare,   even the data is low than normal , it can scan also . And adding another factor,  the rate of scan may not the failed rates in your production line,  that is why scan can be executed successfully . 

 

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daniel_qian1991
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Firstly, thank you very much for reply on time,Mr zhang.

Regarding to 2 of your question, my answer as follows,

First one:

The answer is YES,failed phenomenon is bond with the *** module(based on CYW43340),not the WiFi board except for ***module. At the same time,the failed wifi board can not pass the procedure of scan SSID in mass production line and this test we can call  it is a singnaling way,not non-signaling way with the RF test includes conducted TX and RX measurement. Finally, i believe it is helpful to you that have a  look for the attachment,  it is a picture of Wifi board consists of *** module and other electrical components.

Second one:

First, i want to  clarify  my prior presentation (Step 3) for much deeper understanding. 

"When i take the ***module of failed Wifi board (can not scan any SSID) by air gun  into the fixture test of  module' manufacturer,and the test  is consist of two program including load the wifi firmware firstly and scan the SSID secondly, but the result  indicates the ***module of failed Wifi board can pass the the fixture test of  module' manufacturer and it seems to be proved the *** module is OK ,not damaged.SO, this conclusion is totally opposite with prior step2 called the "cross validation",because step2  has proved to a fact that the *** module on the wifi board is damaged.

In addition , i am sorry to understand your opinion about signal test,can you provide more information for  it ?

Tks sincerely.

Daniel qian

 

 

"

 

 

 

 

 

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Zhengbao_Zhang
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Hello:

   我用中文描述下吧:

1.  产线上发现有2%失败的案例, 用烘枪取下来后到模组的夹具上面测试都是正常的, 是这个意思吗?

   产线上的问题是跟着图中的小板子(包含wifi模组)走的, 板子换到哪里问题到哪里。

那么这些实验做过吗:

a.  板子之间的模组交叉实验

b.  坏的板子有没有产线上面检查过焊接,因为是模组,还不能直接算到芯片侧的问题, 你得先证明模组有问题,才能够怀疑到芯片问题。

c.  可以检查一下module的PA相关的电源的电压是否正常, 如果是internal PA的话, 如果是external PA 请模组厂帮忙分析。

  

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嗯,是这个意思。不良现象是一直跟着模组在走。

a、模组的交叉验证也做过了,不良现象是跟着模组在走;

b、焊接检查过,也照过X光机,都是正常的;

c、目前只验证了模组的电源引脚和SDIO接口,通过和好的模组对比量测上电时序、SDIO时钟等参数,没有发现不良模组和PASS的模组有区别。至于张工说的PA电源,我不确定已经量测了模组引脚上的电源能不能直接等同?

 

现在的问题难点是,因为这个不良模组拆下来在模组厂商的夹具上测试加载WiFi固件和扫描SSID都是正常的,所以模组厂商不认为他们的模组有问题,而是把问题推给我们自己做的转接板board。但实际上我对调模组,不良现象又是跟着模组在走,这说明模组硬件确实存在问题。所以这两个自相“矛盾”的现象,还希望张工指点帮忙,多谢。

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Zhengbao_Zhang
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模组从你们的板子拆下来以后的非信令测试和你们产线是一模一样的吗?  比如产线11n tx Channel 11 失败, 你换到夹具上面就ok了?  

 如果仅仅是TX power方面的问题,而driver load MFG firmware这些一直都没有问题, 我建议从电源和接地的对比方面看看。

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额,是这样的,张工。

我们产线测试和把模组吹下来放到模组厂商的夹具测试,都是信令测试,不是非信令测试。

我们产线只是测试能不能扫描出我们在产线设定好的SSID并连接上,模组厂商的夹具测试主要是加载WiFi固件和扫描SSID测试(包括扫描出SSID,信号强度,连接速率等)两大项,需要说明的是,模组厂商的夹具测试是顶针来完成的,天线都没上,但可以扫描出极其微弱的SSID(信号强度-80左右)。

现在奇怪的地方就是为什么模组拆下来就可以在供应商的夹具上扫描出SSID,在我们转接板board装配上整机里面就扫不到?同时,这种现象在我们好坏机器上交叉验证又是跟着不良模组在走,跟我们整机以及WiFi转接板board没关系。

WiFi转接板board上的电源以及纹波都测试过,是正常的。

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Zhengbao_Zhang
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建议这样做:

1.  有问题的板子用非信令扫一遍,看是否有频偏,EVM啥的是否临界, 我记得EVM和频偏都会影响到scan。

2. 如果第一步没有问题,  可以考虑拿夹具和你们产线的转接板到同一环境下做对比, 只有一致的环境才能说明问题。

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daniel_qian1991
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好的,谢谢张工的建议,因为暂时有问题的板子已经寄给模组厂商了,回头在我们产线验证有结果了再沟通。

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