SAMD21J18A, external Crystal for UART and USB?

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#1
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Hi 

 

I am planning to use the SAMD21J18A for a new project.

 

When using AVR or XMEGA I have always used an 11.0592Mhz crystal for UART purposes. 

 

Do we need to use an external crystal such 11.0592Mhz for the purpose of UART or USB on the SAM?

 

I might also incorporate a USB connection to an external module(GSM). If understood correctly the SAM device be set as a HOST, so it should be able to connect to the module. The reason for using USB is to achieve a higher data rate compared to UART.

 

I will be using a 32.768Khz to wake up the device when it goes into sleep mode, can this be used to stabilize or calibrate an internal clock?

 

 

 

 

 

Thanks

Regards

DJ

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Total votes: 0

You can use 32.768kHz for everything. You can DFLL it to 48MHz needed for the USB Host. The datasheet doesn't seem to recommend it for USB Host (see "GCLK_USB Clock Setup Recommendations"), but they use it on their own SAMD21 Xplained Pro.

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Thanks

 

It makes sense, I believe this would also work with UART for a higher datarate.

 

What is the max baud rate achievable with 48Mhz for UART purpose?

 

 

Thanks

Regards

DJ