LIN Transceiver NCV7329 Arduino connection and pull-up resistor configuration

TECHNICAL SUPPORT Sensors & Modules
1

Customer:

I have purchased the LIN Transceiver NCV7329 breakout board and a Breadboard Power Supply. I need assistance connecting the LIN Transceiver to an Arduino.

Specifically:

  • Do I need to use a 10 kΩ resistor and a 100 µF capacitor to pull up the RX pin to 5V to connect this board to the Arduino?
  • Can I directly connect the TX and RX pins to the Arduino?
  • Can you provide an image or diagram showing how to connect the LIN Transceiver to the Arduino using a breadboard?

Originally submitted via email support on 31 July 2024. Migrated to the forum for community visibility.

2

Soldered Support:

You just have to connect the pins directly - all pull-ups and capacitors are already onboard. The pinout is available at: https://soldered.com/productdata/2022/03/LIN-breakout-1.png

When you connect a breakout to a breadboard, all columns where a board’s pin is connected are internally connected. For example, if you were using pins 8 and 9 for RX and TX with a Dasduino CORE, you would wire the breakout accordingly.

You can use header jumper wires or firm wires for connections.

Attachment omitted in migration: image.png

3

Customer:

Can you please test if this works? I was asking about the 10k Ohm resistor connected to the 3.3V/5V voltage generator and the RXD pin. I can see it on the Transceiver’s product page but I cannot find it in your documentation. I think I might need to apply it to get it working.

Could you please test your Arduino setup?

Also, why is there a pull-down resistor on the EN pin in your schematic when the Transceiver has an integrated one?

Attachment omitted in migration: bPkv7TBXbl1z6mG0.png

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Attachment omitted in migration: image.png

4

Soldered Support:

We added an external 10k resistor to the enable pin because the internal resistor is around 250k, which is too weak for this pin. Regarding the 10k pull-up on the RX pin, you can add it (which is a better option) or use the microcontroller’s internal pull-up on this pin.

I will test the breakout this week and send you the results.

5

Soldered Support:

I tested the connection from the schematic and it works. I connected the EN pin to GPIO 13 and set it HIGH in the code. I sent messages from one module to the other and everything worked.

For RX, I did not use a pull-up resistor because the Atmega328 enables its pull-up when I use Serial on the pins.

Note that you need to connect 5V to the terminal pin marked as VCC to power the module.

6

Customer:

Thank you for testing. I got the LIN Transceivers working now. Could you do me one last favor? Please provide a page or screenshot from the Datasheet where I can see that the Atmega328 uses an internal pull-up on the RX pin.

7

Soldered Support:

The picture shows what is written in the datasheet. Also, if you plan to use pull-ups, you need to activate them in the code. Some libraries do this when you initialize them, and others do not, so you need to check that.

Attachment omitted in migration: Atmega38-pull-ups.png