Apollo3-Explorable SPI pins swap

Development Boards Artemis
1

Hi,

I wondering if is possible to swap the SPI pins (SDI/MISO, SDO/MOSI) of the Thing Plus Eplorable with Apollo3, in the Arduino code.

By default they are routed like this:

SDI/MISO = 25

SDO/MOSI = 28

With the Apollo3 example Example06_SPI is possible to change the pin definitions. Adapted in my code, it compiles and download, but then get error.

here a snip of the code

#include "SPI.h"
#define SPI_MODE SPI_MODE3
//MbedSPI mySPI(mySDI, mySDO, myCLK);
MbedSPI spiPort(28, 25, 27);
..
  spiPort.begin();
  // Do a fake transaction to initialize the SPI pins
 
  spiPort.beginTransaction(SPISettings(4000000, MSBFIRST, SPI_MODE3));
  spiPort.transfer(0);
  spiPort.endTransaction();
..

but then I get this error

++ MbedOS Error Info ++

Error Status: 0x80FF0144 Code: 324 Module: 255

Error Message: Assertion failed: (int)iom != IOM_NUM

Location: 0x33339

File: mbed-os/targets/TARGET_Ambiq_Micro/TARGET_Apollo3/device/spi_api.c+86

Error Value: 0x0

Current Thread: main Id: 0x10005550 Entry: 0x34349 StackSize: 0x1000 StackMem: 0x100071C0 SP: 0x10007F34

For more info, visit: https://mbed.com/s/error?error=0x80FF01 … expLoRaBLE

– MbedOS Error Info –

any idea where the propblem is?

Tnx

2

The specific error code 0x80FF0144 corresponds to an assertion failure in the SPI API of the Mbed OS, indicating that the SPI module configuration is invalid.

3

the Apollo3 processor does not support MISO on GPIO 28, nor MOSi on GPIO 25. The Apollo3 processor has 6 I2C/SPI modules the GPIO for SPI can only be assigned as

  MISO MOSI SCK
M0 6   7   5
M1 9  10   8
M2 25 28  27
M3 43 38  42 
M4 40 44  39 
M5 49 47  48

In the case the Explorable either some of these pins are already in use OR not connected.