Arduino R4 Minima

This board features the R7FA4M1ABxCFM MCU with 256 KiB of FLASH and 32 KiB of SRAM running at 64 MHz (internal clock - HOCO).

See the Arduino website for information about Arduino R4 Minima.

Buttons and LEDs

Buttons

There are no buttons on the Arduino R4 Minima board.

LEDs

There are three user-controllable LEDs on board the Arduino R4 Minima:

LED	GPIO
L Amber LED	P111
TX Yellow LED	P012
RX Yellow LED	P013

LED L is connected to ground and can be illuminated by driving the P111 output high. The TX and RX LEDs are pulled high and can be illuminated by driving the corresponding GPIO output low.

These LEDs are not used by the board port unless CONFIG_ARCH_LEDS is defined. In that case, the usage by the board port is defined in include/board.h and src/ra_autoleds.c. The LEDs are used to encode OS-related events as follows:

SYMBOL	MEANING	L	TX	RX
LED_STARTED	NuttX has been started	OFF	OFF	OFF
LED_HEAPALLOCATE	Heap has been allocated	OFF	OFF	OFF
LED_IRQSENABLED	Interrupts enabled	OFF	OFF	OFF
LED_STACKCREATED	Idle stack created	ON	OFF	OFF
LED_INIRQ	In an interrupt	N/C	GLOW	OFF
LED_SIGNAL	In a signal handler	N/C	GLOW	OFF
LED_ASSERTION	An assertion failed	N/C	GLOW	OFF
LED_PANIC	The system has crashed	N/C	N/C	Blinking
LED_IDLE	MCU is in sleep mode	NA	NA	NA

Thus, if LED L is statically on, NuttX has successfully booted and is apparently running normally. If LED RX is glowing, then NuttX is handling interrupts (and also signals and assertions). If TX is flashing at approximately 2 Hz, then a fatal error has been detected, and the system has halted.

Serial Consoles

The R7FA4M1ABxCFM has a UART and 4 SCI (UARTs).

Any of the SCI interfaces may be used as a serial console. By default, SCI2 is used as the serial console in all configurations. This can be easily changed by modifying the configuration.

Arduino R4 Minima	R7FA4M1ABxCFM
Pin (Label)	SCI Mapping
0 (RX0<-0)	RXD2
1 (TX0->1)	TXD2
13 (12)	RXD9
14 (~11)	TXD9
SWD-7	RXD1
SWD-8	TXD1

Loading Code

It is possible to use J-Link on the SWD connector or use USB Boot available through the USB-C connector.

RA USB Boot:

Reboot the board with BOOT shorted to GND and press the reset button twice (double click). The board will enumerate as “Renesas RA USB Boot.”

Then, flash the nuttx.hex file using rfp-cli: (https://www.renesas.com/en/software-tool/renesas-flash-programmer-programming-gui)

Example command:

rfp-cli -device ra -port /dev/ttyACM0 -p ./build/nuttx.hex

Note: Programming using the binary format will fail because, by default, the RA4M1 NuttX port writes to the .idcode section, which is located beyond the end of the flash area. This causes the RFP to attempt writing to protected regions, leading to failures.