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mizo_4684936
Level 1
Level 1

Hello everyone,

I am designing board including PSoC4200M (CY8C4246AZI-M443). The interface I will be using is LIN, I have seen that it's UART pins have support for that. The transceiver I decided to use is NXP TJA1028, which will also power the MCU mentioned above (3v3 and 5V are available). My question is what are UART logic levels? Is it 3v3 or 5v, I can't find anything about it in datasheet. Does it depend on power supply? If so which is better. Also can someone advise what value  pull-ups on tx and rx pins of transceivers should be and why?

Thanks in advance,

Michał

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1 Solution
BragadeeshV
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hi mizo_4684936​,

The GPIO output drivers are connected to the following

The output drivers of I/O Ports P0 and P7 are connected to VDDD. Output drivers of I/O Ports 1, 2, and 5 are connected to VDDA. Output drivers of I/O Ports 3, 4, and 6 are connected to VDDIO.

Reference. Pg 11 of PSoC 4200 M datasheet.

https://www.cypress.com/file/377971/download

Depending on what ports you have chosen for LIN, the output levels depends on the respective power supply mentioned above.

Pull-ups:

Refer to the schematic of CY8CKIT-026 CAN and LIN Shield Kit for reference:

https://www.cypress.com/file/457901/download

pastedImage_4.png

Also refer to the Section 6.5 LINE DRIVER/RECEIVERELECTRICAL -> DC PARAMETERS  in LIN specification as well.

3.3 V or 5 V can be chosen based on the transceiver specification. Also, 3.3 v leads to lower power consumption compared to 5 V  but the noise performance will be better for 5 V level.

Regards,

Bragadeesh

Regards,
Bragadeesh

View solution in original post

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2 Replies
BragadeeshV
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hi mizo_4684936​,

The GPIO output drivers are connected to the following

The output drivers of I/O Ports P0 and P7 are connected to VDDD. Output drivers of I/O Ports 1, 2, and 5 are connected to VDDA. Output drivers of I/O Ports 3, 4, and 6 are connected to VDDIO.

Reference. Pg 11 of PSoC 4200 M datasheet.

https://www.cypress.com/file/377971/download

Depending on what ports you have chosen for LIN, the output levels depends on the respective power supply mentioned above.

Pull-ups:

Refer to the schematic of CY8CKIT-026 CAN and LIN Shield Kit for reference:

https://www.cypress.com/file/457901/download

pastedImage_4.png

Also refer to the Section 6.5 LINE DRIVER/RECEIVERELECTRICAL -> DC PARAMETERS  in LIN specification as well.

3.3 V or 5 V can be chosen based on the transceiver specification. Also, 3.3 v leads to lower power consumption compared to 5 V  but the noise performance will be better for 5 V level.

Regards,

Bragadeesh

Regards,
Bragadeesh
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Thanks for explanation, everything is clear now.

Stay safe and healthy!

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