更改Arduino uno SD.h上的SPI引脚

Question

I have Arduino uno with ENC28J60 and microSD card reader, both work well independently. The only problem is that they both use the same pins 13,12,11,10. Is there a Way how to change it for another?

I tried to have a look at the SD.h library as it seems more readable to me and change the settings in Sd2PinMap like this

// SPI port
uint8_t const SS_PIN = 5;
uint8_t const MOSI_PIN = 6;
uint8_t const MISO_PIN = 7;
uint8_t const SCK_PIN = 4;

It seems that it didn't take any effect. I matched them so new pins are PWM as well. Is there anything else that should be set? Can they even be changed?
Thanks for your answers

Answer 1

SPI supports multiple devices by using separate slave select lines.

The arrangement that you want is illustrated below (from https://upload.wikimedia.org/wikipedia/commons/thumb/f/fc/SPI_three_slaves.svg/350px-SPI_three_slaves.svg.png )

This means that both devices can share the clock (SCK), input (MISO) and output (MOSI) pins. But each device needs to use a separate select (SS) pin.

Depending on what library you are using to access these devices, then you can configure them to use different select pins.

eg for https://github.com/arduino-libraries/SD you can use:

boolean begin(uint8_t csPin = SD_CHIP_SELECT_PIN);

and for https://github.com/njh/EtherCard you can use:

static uint8_t begin (const uint16_t size, const uint8_t* macaddr,
                      uint8_t csPin = SS);

These methods allow you to change the select pins.