Set SPI Mode on Arduino Uno R4

Question

I am switching a code from Arduino Uno R3 to Arduino Uno R4 Wifi due to the limitation of RAM spaces on R3. I use a thermocouple shield and SD Card read/write shield with the project, which requires me to transfer between mode 3 and mode 0 on R3. However, when I try to do the following code on R4:

SPI.setDataMode(SPI_MODE3); 

The IDE told me that SPI does not have a function named setDataMode. I tried to run the program without using setDataMode, but it does not seem work correctly (SD Cards with empty data).

Compilation error: 'class arduino::ArduinoSPI' has no member named 'setDataMode'

Thank you all for helping. the issue is resolve by using SPISettings variable along with SPI.beginTransaction(SPISettings) and SPI.endTransaction(SPISettings)

• Bh4: The text is pretty much what described in the question, it says: Compilation error: 'class arduino::ArduinoSPI' has no member named 'setDataMode', which this is the command to change data mode using Arduino UNO R3
• jsotola: the message text belongs in the question. not in a comment ... added it for you ... you can delete the comment
• hcheung: The first paragraph of the SPI.setDataMode() documentation said "This function should not be used in new projects. Use SPISettings. with SPI.beginTransaction(). to configure SPI parameters". I wish they could be more explicitly saying "This function is deprecated since 2014 and only exist for backward compatibility reason".
• hcheung: See my answer to a similar question for further explanation.
• Bh4: Thank you for the help @hcheung, the issue is resolved with 'SPISettings' and SPI.beginTransaction(SPISettings)

Answer 1

I looked at SPI.h in the R4 core here: https://github.com/arduino/ArduinoCore-renesas/blob/main/libraries/SPI/SPI.h

It looks like you have to set up a configuration struct and pass to a different function:

arduino::SPISettings const DEFAULT_SPI_SETTINGS = arduino::SPISettings(1000000, MSBFIRST, arduino::SPI_MODE0);
 arduino::SPISettings _settings = arduino::SPISettings(0, MSBFIRST, arduino::SPI_MODE0);

Then in beginTransaction you have the opportunity to pass in those settings:

virtual void beginTransaction(arduino::SPISettings settings);

I'm not 100% sure how that all works, but at least this should get you going in the right direction.

• Bh4: Thanks for the help, you can reply to me either here or on the forum. I will be looking at both sides, and I will post solutions either from forum or from here once we have a solution
• Delta_G: It would be better if you had only one post. It's mostly the same people on both sites. Your post there is probably better because there are a few of us that have been digging really deep on the R4.
• Delta_G: Have you tried this? Create the settings you need following the model in this answer and then try passing that to beginTransaction