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Hithesh
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Hi team,

We are facing an issue regarding changing an MCU from  XMC1403Q040X0200AAXUMA1 to XMC4108Q48K64BAXUMA1.

In XMC1403Q040X0200AAXUMA1 , We have SPI chip select  of 4 numbers. But in new XMC4108Q48K64BAXUMA1, We have only 2 chip select pins available as per XMC Pinout Tool and DAVE IDE. Can we use GPIO's as a Chip select pins?

Hithesh_1-1672037165557.png                                                                                                      

XMC1403Q040X0200AAXUMA1 PIN OUT Tool 

Hithesh_0-1672037060724.png

XMC4108Q48K64BAXUMA1 PIN OUT Tool 

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1 Solution
LinglingG_46
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1: If you use the device which offer 4 slave select signals which you need, you can config it directly.

LinglingG_46_0-1672196646208.png

2: If you want to use the xmc4108-48pin chip which don't have dedicated four SSC slave select signals, you can use the GPIO to control. 

3: I don't think GPIO control is far better, but as you said, it can create the communication. You can set up a test project to test it.

 

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LinglingG_46
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The XMC4108Q48K64BAXUMA1 SPI SS pin numbers can only be configured as 2. Because of the hardware restriction.

Your GPIO pins can't be used to act as the ss pin. But if you want to use the GPIO to emulate the SPI, it is another thing.

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Thank you @LinglingG_46 for your response. We are not trying to emulate SPI but only changing CS pin since we have 4+ slaves sharing the same SPI. Normally in Controllers It's possible to implement the same. Can you explain in detail why it is not possible in XMC4108Q48K64BAXUMA1

Hithesh_1-1672058019491.png

 

 

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LinglingG_46
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XMC4108Q48K64BAXUMA  only supports one CS (chip select) pin.

Just like the pinout tool, it has two choices, one is P0.7 and another is P1.0.

If you want to have 4 slaves, it is recommended that you can choose another part of device which support the feature.

 

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@LinglingG_46 

Once we give a low voltage at CS pin of any slave device, it enables the communication between master and Slave. GPIO could be far better for that operation right? What makes you to say only dedicated pin works?

We already have this part in bulk stock and would like to get a very detailed explanation from your Firmware experts too. 

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LinglingG_46
Moderator
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10 questions asked 5 questions asked 250 sign-ins

1: If you use the device which offer 4 slave select signals which you need, you can config it directly.

LinglingG_46_0-1672196646208.png

2: If you want to use the xmc4108-48pin chip which don't have dedicated four SSC slave select signals, you can use the GPIO to control. 

3: I don't think GPIO control is far better, but as you said, it can create the communication. You can set up a test project to test it.

 

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