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USB superspeed peripherals Forum Discussions

Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

Dear community,

First of all, I'd like to know if it is possible to use CyU3PDebugPrint API while SPI peripheral has been activated. As the pins are shared, I can see with the USBSpiRegMode example that nothing is printed on Tera Term. However, there is a debugprint statement in the main thread (and it is executed in step by step mode).

On the other hand, I encounter an issue with the SPI peripheral on the MOSI signal. I attached a picture of the capture (in analog mode) and I can see that this signal toggles between 1.3-1.4V & 3V3. I'd like to know if someone has encountered a similar issue and how to solve this problem.

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello,

Please find the attached capture at our end using an Explorer kit.

JayakrishnaT_76_0-1658825959891.png

We were not able to reproduce the issue using explorer kit at our end. It looks like there could be an issue with the ground connection in your analyzer. Please check the analyzer settings too. If you still find the issue, then can you please check on a different explorer kit?

Best Regards,
Jayakrishna

View solution in original post

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello,

Firstly, as you might be knowing,  FX3 IOs are multiplexed. So, the mapping of IOs to peripherals are done through firmware. You can refer to the API CyU3PDeviceConfigureIOMatrix () to understand this better. For the default USBSpiRegMode, FX3 makes use of the IO configuration 16 bit data bus + UART + SPI + I2S. Please refer to the Table 7 of FX3 datasheet to understand the pin mapping in this configuration. The reason for not obtaining the prints could be that the UART-USB bridge used on your board might be connected to GPIO[53:56] but the UART in this configuration is at GPIO[46:49]. Please check and correct this so that you will be able to get the prints.

Regarding the MOSI signal, we have not seen such a behavior before. Please share the following details so that we can understand the problem better:

1. Do the signal toggles showing the same behavior always? Or does it occur only at some specific time?

2. Do all the boards show the same behavior or is it only for a few boards? What is the failure rate?

3. Can you please share the schematics of your board for us to check?

Best Regards,
Jayakrishna
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Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

So if I understand correctly, in the mentioned example, I'm in the configuration where UART, SPI, I2S are activated (I2C also but its pins never changes). Because I use CY_U3P_IO_MATRIX_LPP_DEFAULT.

So SPI pins are GPIO53 to 56 (D4, C1, C2, D5) and UART pins are GPIO46 to 49 (F5, E1, E5, E4). So it is not possible for me (without modifications of the board) to use CyU3PDebugPrint API as they are not connected to chip Cy7C65215 (UART to virtual COM port over USB).

Okay, however this isn't my main issue here.

Response to 1) Yes, the signal toggles showing the same behavior always.

Response to 2) I have only one board so I can't compare with other.

Response to 3) The schematic has been attached to this response.

Some more details :

What I see with the scope when I use my program and when I use the example is that the MOSI pin toggle always between 1.3-1.4V and 3V3.

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Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

Would it be possible that U3 (CY7C65215 - UART to virtual COM port over USB) causes the issue ? With some pullup / pulldown configuration of the input pin ?

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hi,

Based on my understanding, you are using FX3 Superspeed Explorer kit. Please confirm if my understanding is correct or not. If my understanding is correct, then we will check and try to reproduce the issue at our end to debug the issue faster.

Also, can you please test by not connecting the USB cable to J8 (USB receptacle) on the board? This will not power the U3 component. Thereby we can check if it is due to U3 or not.

Best Regards,
Jayakrishna
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Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

Yes, I'm using FX3 Superspeed Explorer kit.

I tried to unplug J8 and I also unplugged MISO & MOSI signals from my chip.

Unfortunately, the signal still toggles between 1.3 & 3.3V.

Best regards, von Siebenthal Christophe

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello,

Have you connected any SPI slave to the SPI bus? Or have you just left it open?

Best Regards,
Jayakrishna
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Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

SSN is left unconnected. MOSI is left unconnected. MISO is still connected. SCK is still connected.

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello,

Please find the attached capture at our end using an Explorer kit.

JayakrishnaT_76_0-1658825959891.png

We were not able to reproduce the issue using explorer kit at our end. It looks like there could be an issue with the ground connection in your analyzer. Please check the analyzer settings too. If you still find the issue, then can you please check on a different explorer kit?

Best Regards,
Jayakrishna
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Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

I also measured the signals with an oscilloscope : same behavior so it's not my Saleae connections.

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello,

Can you please try to test with a different explorer kit? Also, how was the data transferred? You can use the following settings in control center to perform the data transfer:

JayakrishnaT_76_0-1658826332849.png

 

Best Regards,
Jayakrishna
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Christophe
Level 3
10 replies posted 5 questions asked 5 replies posted
Level 3

I unplugged everything from my board and the signal toggles between 0 & 3V3 now. Thank you for your help, I have something wrong on my side. I have to understand what and why.

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JayakrishnaT_76
Moderator
Moderator First question asked 1000 replies posted 750 replies posted
Moderator

Hello,

We are glad to hear that the issue is resolved.

Best Regards,
Jayakrishna
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