choice of SPI port

[Nocentinia]

I recently bought a new Arduino GIGA R1 WIFI which has multiple ports for SPI communication. The SPI1 port (defined as the SPI object by the "SPI" library) that is used by this library is broken out to the SPI header in the center of the board. The SPI5 port (defined as the SPI1 object by the "SPI" library) is located between pins 10 and 13 in the female pins.

In some cases, it may be necessary or more convenient to connect the SD card to the SPI5 bus. However, it is not feasible to use this library with that configuration because it is hardcoded to use the SPI object:

SD/src/utility/Sd2Card.cpp

Lines 27 to 29 in e5438e2

	#ifndef SDCARD_SPI
	#define SDCARD_SPI SPI
	#endif

There is a macro-based mechanism for configuring the object name. However, defining that SDCARD_SPI macro could only be done either by setting platform properties (which is something only very advanced users will be able to accomplish), or by editing the library's source code (which is also difficult for the average user).

Please add an interface that allows the user to pass an object to the library for use in communicating with the SD card.

Additional context

Such a capability has already been implemented in the SdFat library:

https://github.com/greiman/SdFat/blob/2.3.1/src/SdCard/SdSpiCard/SpiDriver/SdSpiDriver.h#L110-L118

and in the "SD" library that is bundled with the "Arduino ESP32 Boards" and "esp32" platforms:

https://github.com/espressif/arduino-esp32/blob/3.3.0/libraries/SD/src/SD.h#L30-L32

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Related forum discussion:

https://forum.arduino.cc/t/choice-of-spi-port/1178433

Related

• https://forum.arduino.cc/t/using-sd-card-with-giga-r1-wifi/1406124
• https://forum.arduino.cc/t/using-sd-cards-on-arduino-giga/1153635/48
• https://forum.arduino.cc/t/arduino-giga-r1-and-sd-card/1221185/2

[UniquePete]

I have a similar problem with the Heltec CubeCell Plus Dev-Board—its SPI1 (that's the second SPI bus in this case) pins are more conveniently located than the SPI pins and would generally be those used to connect SPI devices.

I note that the ESP32 version of the SD library includes the ability to specify the SPI bus to be used. It would be good if this option were also available in the present version of the library.