EK-RA8M1

This is a port of NuttX to the Renesas EK-RA8M1 evaluation kit, featuring the R7FA8M1AHECBD (BGA224) MCU: an Arm Cortex-M85 running at up to 480 MHz, with 2016 KiB of code flash, 896 KiB of SRAM and 12 KiB of data flash.

See the Renesas website for information about the EK-RA8M1.

Flat, no-TrustZone image

This port does not use TrustZone: it is a flat image that always runs in the secure state, and it uses the secure memory and register aliases throughout (RA8M1 User’s Manual Table 4.1) – code flash at 0x0200_0000, SRAM at 0x2200_0000, data flash at 0x2700_0000. The non-secure aliases (0x12xx_xxxx/0x32xx_xxxx/0x37xx_xxxx) are not used.

The EK-RA8M1 ships with the TrustZone security partition set to the Renesas FSP sample project’s boundary. A flat NuttX image needs the whole flash marked secure instead, which has to be set once with the flash programmer before the first NuttX image is written (see Loading Code below).

Clocking

include/board.h configures this clock tree from the EK-RA8M1’s 20 MHz resonator (see arch/arm/src/ra8m1/ra_clockconfig.h for how every option is derived and validated):

Clock	Source	Frequency
MOSC	20 MHz resonator on EXTAL/XTAL	20 MHz
PLL1	MOSC / 2, x96	960 MHz VCO
CPUCLK	PLL1 output P / 1	480 MHz
ICLK	PLL1 output P / 2	240 MHz
PCLKA	PLL1 output P / 4	120 MHz
PCLKB	PLL1 output P / 8	60 MHz
PCLKC	PLL1 output P / 8	60 MHz
PCLKD	PLL1 output P / 4	120 MHz
PCLKE	PLL1 output P / 2	240 MHz
FCLK	PLL1 output P / 8	60 MHz
BCLK	PLL1 output P / 4	120 MHz
SCICLK	PLL1 output Q / 4	120 MHz

SCICLK feeds the baud rate generator of every SCI UART; it is only configured (and its PLL only started) when at least one CONFIG_RA_SCIn_UART is enabled. 120 MHz was chosen because it gives 115200 baud with 0.16 % error (the reset default, the 8 MHz MOCO, gives 3.5 % error).

Buttons and LEDs

Buttons

No push-buttons are wired into this port.

LEDs

The EK-RA8M1 has three user LEDs:

LED	GPIO	Colour
LED1	P600	Blue
LED2	P414	Green
LED3	P107	Red

They are driven active-high in this port (ra8m1_userleds.c, ra8m1_autoleds.c); this has not been confirmed on hardware, so if a board turns out to be wired the other way, invert the levels there.

These LEDs are not used by the board port unless CONFIG_ARCH_LEDS is defined. In that case, the usage is defined in include/board.h and src/ra8m1_autoleds.c:

SYMBOL	MEANING	LED1	LED2	LED3
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	ON	N/C
LED_SIGNAL	In a signal handler	N/C	ON	N/C
LED_ASSERTION	An assertion failed	N/C	ON	N/C
LED_PANIC	The system has crashed	N/C	N/C	ON

Without CONFIG_ARCH_LEDS, the LEDs are available through the userled upper half at /dev/userleds (bit 0 = LED1, bit 1 = LED2, bit 2 = LED3), or individually through the ULEDIOC_SETLED ioctl.

Serial Console

The EK-RA8M1’s on-board debugger (a J-Link) provides a virtual COM port on SCI9:

Signal	R7FA8M1AHECBD
TXD9	PA14
RXD9	PA15

SCI9 is the serial console in the default configurations, at 115200 8N1.

Loading Code

This port produces a flat image (no TrustZone), so it is flashed with rfp-cli (the Renesas Flash Programmer CLI), through the on-board J-Link, over SWD:

rfp-cli -device ra --tool jlink -if swd -p ./build/nuttx.hex

Note: the image must be flashed as ELF, HEX or SREC, not as a raw binary: the option-setting words (OFS0/OFS1/OFS2, see ra_option_setting.c) sit in flash option memory well above the code flash region, and a raw objcopy binary would not carry them.

Note: a board fresh from the factory, or last flashed with the Renesas some project, has the TrustZone boundary set to that project’s partition, which might too small for this flat image and makes rfp-cli fail to erase/program with an address error. Set the whole flash and SRAM to secure once, before the first NuttX flash:

rfp-cli -d ra -t jlink -if swd -erase-chip

This is a persistent, one-time device setting; it does not need to be repeated on later flashes of a NuttX image.

Configurations

nsh

Configures the NuttX Shell (nsh) with the serial console on SCI9, plus the ostest test suite.

nsh-leds

Same as nsh, but without ostest, and enables the userled driver on /dev/userleds (CONFIG_ARCH_LEDS is not set, so NuttX does not drive the LEDs itself; see LEDs above).