SPI transactions became officially part of Arduino SPI library some time ago. This happened after many months (most of 2014) of lengthy discussion and testing for these and MANY other details.

September 29, 2009 -- Moortec Announces SPI Block (MR74040) for Low Power Applications. The MR74040 is a synchronous serial-data interface adhering to the SPI protocol of communications. Configurable ...

The second mode is SPI mode. SPI is slower, but much, much simpler. It turned out the SDIO mode on [Severin]’s card was broken, but accessing it with an Arduino and SPI mode worked.

Prestissimo Uno+ Arduino dev board with extra I2C UART SPI ADC IO and PWM channels. 2:24 pm November 5, 2018 By Julian Horsey.

Configurable for all 4 SPI modes* this block acts as a single slave. The design targets the 0.18um CMOS (ca18ha) process offered by Jazz. The MR74040 consists of 32, 16-bit wide R/W registers, 28 of ...