LoRaWAN example SX1272 + NUCLEO-L433RC Hardfault [SOLVED]


I’m trying to use the SX1272 LoRa Shield on a Nucleo -L433RC board with the LoRaWan example provided by mbed.

The shield is not pin-to-pin compatible (mainly the SPI interface) with the Nucleo board so I connected both boards using cables and modified the mbed_app.json file to redefine the pins I used to connect both boards and to set the SX2172 as lora-radio as follows:

   "config": {
    "lora-radio": {
        "help": "Which radio to use (options: SX126X, SX1272, SX1276) -- See config/ dir for example configs",
        "value": "SX1272"
"main_stack_size":     { "value": 4096 },

    "lora-spi-mosi":       { "value": "PA_7" },
    "lora-spi-miso":       { "value": "PA_6" },
    "lora-spi-sclk":       { "value": "PA_5" },
    "lora-cs":             { "value": "PA_4" },
    "lora-reset":          { "value": "PA_0" },
    "lora-dio0":           { "value": "PA_12" },
    "lora-dio1":           { "value": "PB_3" },
    "lora-dio2":           { "value": "PB_5" },
    "lora-dio3":           { "value": "PA_15" },
    "lora-dio4":           { "value": "NC" },
    "lora-dio5":           { "value": "NC" },
    "lora-rf-switch-ctl1": { "value": "NC" },
    "lora-rf-switch-ctl2": { "value": "NC" },
    "lora-txctl":          { "value": "NC" },
    "lora-rxctl":          { "value": "NC" },
    "lora-ant-switch":     { "value": "NC" },
    "lora-pwr-amp-ctl":    { "value": "NC" },
    "lora-tcxo":           { "value": "NC" }
"target_overrides": {
    "*": {
        "platform.stdio-convert-newlines": true,
        "platform.stdio-baud-rate": 115200,
        "platform.default-serial-baud-rate": 115200,
        "lora.over-the-air-activation": true,
        "lora.duty-cycle-on": true,
        "lora.phy": "US915",
        "lora.device-eui": "{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }",
        "lora.application-eui": "{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }",
        "lora.application-key": "{ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
           0x00, 0x00, 0x00, 0x00 }",
        "target.components_add": ["SX1272"]

The code compiles but I’m getting a hardfault message:

++ MbedOS Fault Handler ++

FaultType: HardFault

R   0: 00000000
R   1: 20010000
R   2: 00000001
R   3: 20010000
R   4: 20010000
R   5: 00000003
R   6: 20001260
R   7: 20003AD8
R   8: 20003AE8
R   9: 20004540
R  10: 00000000
R  11: 00000000
R  12: 080015A5
SP   : 20003A8C
LR   : 0800ADEB
PC   : 080101E4
xPSR : 01000200
PSP  : 20003A68
MSP  : 2000FFC0
CPUID: 410FC241
HFSR : 40000000
MMFSR: 00000082
BFSR : 00000000
UFSR : 00000000
DFSR : 00000008
AFSR : 00000000
MMFAR: 00000000
Mode : Thread
Priv : Privileged
Stack: PSP

-- MbedOS Fault Handler --

++ MbedOS Error Info ++
Error Status: 0x80FF013D Code: 317 Module: 255
Error Message: Fault exception
Location: 0x80101E4
Error Value: 0x20003BC0
Current Thread: main Id: 0x20002338 Entry: 0x8002841 StackSize: 0x1000 StackMem: 0x20002BC0 SP: 0x20003A8C 
For more info, visit: https://mbed.com/s/error?error=0x80FF013D&tgt=NUCLEO_L433RC_P
-- MbedOS Error Info --

I had similar faults when some interface was assigned to a pin not designed for such interface, so I checked the mbed_config.h file after compiling to see if the pins were set correctly and found the new pins are there:

#define MBED_CONF_APP_LORA_CS                                                 PA_4 // set by application                                                                                              
#define MBED_CONF_APP_LORA_DIO0                                               PA_12 // set by application                                                                                              
#define MBED_CONF_APP_LORA_DIO1                                               PB_3 // set by application                                                                                               
#define MBED_CONF_APP_LORA_DIO2                                               PB_5 // set by application                                                                                              
#define MBED_CONF_APP_LORA_DIO3                                               PA_15 // set by application                                                                                              
#define MBED_CONF_APP_LORA_DIO4                                               NC // set by application                                                                                                 
#define MBED_CONF_APP_LORA_DIO5                                               NC // set by application                                                                                                 
#define MBED_CONF_APP_LORA_PWR_AMP_CTL                                        NC // set by application                                                                                                 
#define MBED_CONF_APP_LORA_RADIO                                              SX1272 // set by application                                                                                                 
#define MBED_CONF_APP_LORA_RESET                                              PA_0 // set by application                                                                                               
#define MBED_CONF_APP_LORA_RF_SWITCH_CTL1                                     NC // set by application                                                                                                 
#define MBED_CONF_APP_LORA_RF_SWITCH_CTL2                                     NC // set by application                                                                                                 
#define MBED_CONF_APP_LORA_RXCTL                                              NC // set by application                                                                                                 
#define MBED_CONF_APP_LORA_SPI_MISO                                           PA_6 // set by application                                                                                               
#define MBED_CONF_APP_LORA_SPI_MOSI                                           PA_7 // set by application                                                                                              
#define MBED_CONF_APP_LORA_SPI_SCLK                                           PA_5 // set by application       

Also on the same file I found this #define lines:

#define MBED_CONF_SX1272_LORA_DRIVER_SPI_CS                                   NC // set by library:sx1272-lora-driver                                                                                           
#define MBED_CONF_SX1272_LORA_DRIVER_SPI_FREQUENCY                            8000000  // set by library:sx1272-lora-driver                                                                                         
#define MBED_CONF_SX1272_LORA_DRIVER_SPI_MISO                                 NC     // set by library:sx1272-lora-driver                                                                                                

#define MBED_CONF_SX1272_LORA_DRIVER_SPI_MOSI                                 NC   // set by library:sx1272-lora-driver                                                                                              
#define MBED_CONF_SX1272_LORA_DRIVER_SPI_SCLK                                 NC  // set by library:sx1272-lora-driver                                                                                                 
#define MBED_CONF_SX1272_LORA_DRIVER_TCXO                                     NC  // set by library:sx1272-lora-driver                                                                                               
#define MBED_CONF_SX1272_LORA_DRIVER_TXCTL                                    NC  // set by library:sx1272-lora-driver

So I´m not sure the mbed_app.json is actually being used or not to set the SX1272 pins correctly.

Any ideas or suggestions are more than welcome!

Best regards,


Update: The problem was not in the SPI config but an old version of the GCC-ARM toolchain used to compile the code. After updating GCC-ARM to the latest version the hard faults are gone.