RE: Bare metal programming on the nRF9160

nleday — Mon, 16 Oct 2023 11:10:55 GMT

This post just saved me a few hours, thanks a lot ;)

RE: Bare metal programming on the nRF9160

Nguyen Hoan Hoang — Wed, 19 Oct 2022 20:13:34 GMT

Have a look here https://github.com/IOsonata/IOsonata/tree/master/ARM/Nordic

RE: Bare metal programming on the nRF9160

PVH — Wed, 19 Oct 2022 18:37:39 GMT

Thanks, Sigurd :-)

I have now created a makefile that can build a "blinky" example without Zephyr. I have only tested this with the nrfx.h header, but I guess that it is possible to add C files from the nrfx library to the object list in the makefile, if one wishes to use the nrfx library for more than just easy register access.

Example output when building and flashing:

Creating directory build
[CC] main.c --> build/main.o
Creating directory build/cmsis
[AS] /opt/nrfx-2.9.0/mdk/gcc_startup_nrf9160.S --> build/cmsis/startup.o
[CC] /opt/nrfx-2.9.0/mdk/system_nrf9160.c --> build/cmsis/system.o
[LD] build/blinky.axf
[OBJCOPY] ./build/blinky.axf --> ./build/blinky.hex
[OBJCOPY] ./build/blinky.axf --> ./build/blinky.bin

   text	   data	    bss	    dec	    hex	filename
   2144	    108	     36	   2288	    8f0	./build/blinky.axf

Flashing ./build/blinky.hex
Parsing image file.
Verifying programming.
Verified OK.
Applying system reset.
Run.

It actually works and makes the LEDs light up on the board :-)

main.c

// Bare metal nRF9160 DK "Blinky" example                     PVH, October 2022
#include "nrfx.h"

int main()
{
    // LED1..4 on the nRF9160 DK are connected to P0.02..P0.05 and are active 
    // high, so we first configure these pins on P0 as outputs
    NRF_P0->DIRSET |= (1<<5) | (1<<4) | (1<<3) | (1<<2);

    while (1)
    {
        // In the main loop, we make each of the LEDs light up one at a time
        for (uint32_t i = 0; i < 4; ++i)
        {
            NRF_P0->OUTSET |= 1<<(i+2);
            
            // Some delay
            volatile uint32_t j = 1000000;
            while (j > 0)
                --j;
            
            NRF_P0->OUTCLR |= 1<<(i+2);
        }    
    }
    
    return 0;
}

Makefile

# Makefile for nRF9160 bare metal programming                 PVH, October 2022

# Arm GNU toolchain can be found here (look for gcc-arm-none-eabi)
# https://developer.arm.com/Tools%20and%20Software/GNU%20Toolchain
# nrfx is available at https://github.com/NordicSemiconductor/nrfx
# CMSIS can be found at https://github.com/ARM-software/CMSIS_5

# Paths to toolchain and SDK
TOOLSPATH = /opt/gcc-arm-none-eabi-9-2020-q2-update
NRFXPATH = /opt/nrfx-2.9.0
CMSISPATH = /opt/CMSIS_5/CMSIS

# Specify project name, object files, headers (DEPS) and linker script
PROJECT = blinky
OBJ = main.o
DEPS =
LDSCRIPT = ${NRFXPATH}/mdk/nrf9160_xxaa.ld
BUILDDIR = ./build

# Startup and system code
ASTART = ${NRFXPATH}/mdk/gcc_startup_nrf9160.S
SYSSRC = ${NRFXPATH}/mdk/system_nrf9160.c

# Common flags for CC, AS and LD
FLAGS = -mcpu=cortex-m33 -mthumb -mfloat-abi=hard -mabi=aapcs  
FLAGS += -mfpu=fpv5-sp-d16 -DNRF9160_XXAA
FLAGS += -DCONFIG_GPIO_AS_PINRESET -DFLOAT_ABI_HARD

# Shortcuts for various tools
CC = ${TOOLSPATH}/bin/arm-none-eabi-gcc
AS = ${TOOLSPATH}/bin/arm-none-eabi-gcc
LD = ${TOOLSPATH}/bin/arm-none-eabi-gcc
OBJCOPY = ${TOOLSPATH}/bin/arm-none-eabi-objcopy
SIZETOOL = ${TOOLSPATH}/bin/arm-none-eabi-size

# Compiler flags
CFLAGS = ${FLAGS} -std=c99 -Wall -Werror
CFLAGS += -I"${NRFXPATH}/templates" -I"${NRFXPATH}/mdk"
CFLAGS += -I"${NRFXPATH}" -I"${CMSISPATH}/Core/Include"
CFLAGS += -I"${NRFXPATH}/hal" -I"${NRFXPATH}/drivers/include"

# Assembler flags
AFLAGS = ${FLAGS} -x assembler-with-cpp

# Linker flags
LDFLAGS = ${FLAGS} -T "$(LDSCRIPT)" -Xlinker
LDFLAGS += --gc-sections -Xlinker -Map="$(BUILDDIR)/$(PROJECT).map" 
LDFLAGS += --specs=nano.specs
LDFLAGS += -L"${NRFXPATH}/mdk/"
LIBS = -Wl,--start-group -lgcc -lc -lnosys -Wl,--end-group

# Check whether to optimize or build for debugging
DEBUG ?= 0
ifeq ($(DEBUG), 1)
	CFLAGS += -O0 -g3 -gdwarf-2
	AFLAGS += -g3 -gdwarf-2
	LDFLAGS += -g3
else
	CFLAGS += -O3
endif

# Substitute the correct path for the object filenames
_OBJ = $(patsubst %,$(BUILDDIR)/%,$(OBJ))

# Define operations
define COMPILE
	@echo "[CC] $< --> $@"
	@$(CC) $(CFLAGS) -c -o $@ $<
endef

define ASSEMBLE
	@echo "[AS] $< --> $@"
	@$(AS) $(AFLAGS) -c -o $@ $<
endef

define OBJECTCOPY
	@echo "[OBJCOPY] $(2)$(3) --> $(2)$(4)"
	@$(OBJCOPY) $(1) $(2)$(3) $(2)$(4)
endef

define CREATEDIR
	@echo "Creating directory $@"
	@mkdir -p $@
endef

# Build the project

$(BUILDDIR)/$(PROJECT).axf: $(_OBJ)  \
    $(BUILDDIR)/cmsis/startup.o $(BUILDDIR)/cmsis/system.o
# Link
	@echo "[LD] $@"
	@$(LD) $(LDFLAGS) -o $(BUILDDIR)/$(PROJECT).axf \
	$(BUILDDIR)/cmsis/startup.o \
	$(BUILDDIR)/cmsis/system.o \
	$(addprefix $(BUILDDIR)/, $(OBJ)) $(LIBS)
# Generate hex and bin files
	$(call OBJECTCOPY,-O ihex,$(BUILDDIR)/,"$(PROJECT).axf","$(PROJECT).hex")
	$(call OBJECTCOPY,-O binary,$(BUILDDIR)/,"$(PROJECT).axf","$(PROJECT).bin")
# Run the size tool
	@echo ""
	@$(SIZETOOL) $(BUILDDIR)/"$(PROJECT).axf"
	@echo ""
	
all: $(BUILDDIR)/$(PROJECT).axf

$(BUILDDIR):
	$(call CREATEDIR)

$(BUILDDIR)/cmsis: 	
	$(call CREATEDIR)
	
$(BUILDDIR)/cmsis/startup.o: $(ASTART) | $(BUILDDIR)/cmsis
	$(call ASSEMBLE)
    	
$(BUILDDIR)/cmsis/system.o: $(SYSSRC) | $(BUILDDIR)/cmsis
	$(call COMPILE)

$(BUILDDIR)/%.o: %.c $(DEPS) | $(BUILDDIR)
	$(call COMPILE)
	
# Remove builded stuff
clean:
	rm -dfr $(BUILDDIR)

# Flash the program
flash: $(BUILDDIR)/$(PROJECT).axf
	@echo Flashing $(BUILDDIR)/$(PROJECT).hex
	@nrfjprog -f nrf91 --program $(BUILDDIR)/$(PROJECT).hex --sectorerase \
	--verify --reset

erase:
	@echo Erasing all flash
	@nrfjprog -f nrf91 --eraseall

The makefile is a bit messy and may contain errors or suboptimal settings or flags, so any suggestions are welcome, but so far, so good :-)

RE: Bare metal programming on the nRF9160

Sigurd — Mon, 17 Oct 2022 12:21:31 GMT

Hi,

See this post:

Development on nrf9160 DK without zepyhr