Let's run Apache #NuttX OS on RISC-V #BL602

https://nuttx.apache.org/docs/latest/platforms/risc-v/bl602/index.html

Apache #NuttX OS is super interesting because 1️⃣ It runs on all kinds of MCUs 2️⃣ Its APIs work like POSIX (Linux-lite)

https://nuttx.apache.org/docs/latest/introduction/about.html

#NuttX OS works on Arm, #RISCV and ESP32

https://nuttx.apache.org/docs/latest/platforms/index.html

#NuttX #BL602 builds easily on WSL Ubuntu ... Uses plain "make" with "kconfig"

https://nuttx.apache.org/docs/latest/platforms/risc-v/bl602/index.html

We flash #NuttX Firmware to #BL602 ... With the excellent "blflash" by spacemeowx2

https://github.com/spacemeowx2/blflash

#NuttX boots OK on PineCone #BL602 ... Also on PineDio Stack #BL604! 🎉

https://nuttx.apache.org/docs/latest/platforms/risc-v/bl602/index.html

Default #BL602 #NuttX Firmware includes 2 Demo Apps: "hello" and "timer"

https://github.com/apache/incubator-nuttx-apps/tree/master/examples/hello

https://github.com/apache/incubator-nuttx-apps/tree/master/examples/timer

#NuttX Demo Apps are configured before build with "make menuconfig"

https://nuttx.apache.org/docs/latest/quickstart/configuring.html

#BL602 #NuttX "Hello World" ... Looks exactly like on Linux

https://github.com/apache/incubator-nuttx-apps/blob/master/examples/hello/hello_main.c

Timer Demo on #BL602 #NuttX opens "/dev/timer0" ... And controls it with "ioctl" and "sigaction" ... Looks like Linux

https://github.com/apache/incubator-nuttx-apps/blob/master/examples/timer/timer_main.c

Here are the #BL602 Peripherals supported by #NuttX OS

https://nuttx.apache.org/docs/latest/platforms/risc-v/bl602/index.html#bl602-peripheral-support

Though SPI with DMA is not yet supported on #BL602 #NuttX OS

https://github.com/apache/incubator-nuttx/blob/master/arch/risc-v/src/bl602/bl602_spi.c#L734-L761

Here are the Pin Definitions for #BL602 #NuttX ... We'll change this in a while

https://github.com/apache/incubator-nuttx/blob/master/boards/risc-v/bl602/bl602evb/include/board.h

Let's enable the "help" and "ls" Shell Commands in #BL602 #NuttX

https://nuttx.apache.org/docs/latest/quickstart/configuring.html

Let's test GPIO on #BL602 #NuttX ... By enabling the GPIO Driver

https://nuttx.apache.org/docs/latest/quickstart/configuring.html

After the GPIO Driver has been enabled, select the GPIO Demo in #BL602 #NuttX

https://nuttx.apache.org/docs/latest/quickstart/configuring.html

"help" shows the commands available on #BL602 #NuttX ... "ls /dev" reveals the GPIO Pins that we may control ... Yep everything looks like a file!

https://acassis.wordpress.com/2021/01/24/how-to-install-nuttx-on-bl602/

GPIO Demo calls "ioctl" to control the GPIO Pins on #BL602 #NuttX

https://github.com/apache/incubator-nuttx-apps/blob/master/examples/gpio/gpio_main.c

How shall we flip GPIO 11, the Blue LED on PineCone #BL602? We edit the #NuttX GPIO Pin Definition ... And GPIO 11 becomes "/dev/gpout1"

https://github.com/lupyuen/incubator-nuttx/blob/master/boards/risc-v/bl602/bl602evb/include/board.h#L45-L53

Flipping GPIO 11 doesn't blink the LED on #BL602 #NuttX ... Let's investigate 🤔

https://github.com/lupyuen/incubator-nuttx/blob/master/boards/risc-v/bl602/bl602evb/include/board.h#L45-L53

#NuttX writes correctly to the GPIO 11 Output Register at 0x40000188 (BL602_GPIO_CFGCTL32)

https://github.com/apache/incubator-nuttx/blob/master/arch/risc-v/src/bl602/bl602_gpio.c#L190-L209

#NuttX configures #BL602 GPIO 11 (0x40000114) with GPIO Input Disabled ... But it doesn't Enable GPIO Output 🤔

https://github.com/apache/incubator-nuttx/blob/master/arch/risc-v/src/bl602/bl602_gpio.c#L59-L133

#BL602 Reference Manual says we should set the GPIO Output Enable Register ... But it's missing from the docs ... Where is the register? 🤔

https://github.com/bouffalolab/bl_docs/tree/main/BL602_RM/en

#BL602 IoT SDK says that GPIO Output Enable Register is at 0x40000190 (GLB_GPIO_CFGCTL34) ... Let's set this register in #NuttX

https://github.com/lupyuen/bl_iot_sdk/blob/master/components/bl602/bl602_std/bl602_std/StdDriver/Src/bl602_glb.c#L1990-L2010

We mod #BL602 #NuttX to set the GPIO Output Enable Register at 0x40000190 (BL602_GPIO_CFGCTL34)

https://github.com/lupyuen/incubator-nuttx/pull/1/files

After fixing GPIO Output, #NuttX now blinks the Blue LED (GPIO 11) on PineCone #BL602! 🎉

https://github.com/lupyuen/incubator-nuttx/pull/1/files

Blinking the #BL602 LED ... Works on #NuttX BASIC too! 🎉

https://github.com/lupyuen/incubator-nuttx-apps/tree/master/interpreters/bas

As we've seen, #NuttX has its own HAL for #BL602 ... Which differs from BL602 IoT SDK ... So we expect some quirks

https://github.com/apache/incubator-nuttx/tree/master/arch/risc-v/src/bl602

Testing Apache #NuttX OS on #RISCV #BL602 and BL604 ... All shall be explained in this article

https://lupyuen.github.io/articles/nuttx?1

How we build Apache #NuttX OS for #BL602 and BL604

https://lupyuen.github.io/articles/nuttx?2#build-nuttx

Booting #NuttX OS on #BL602 and BL604

https://lupyuen.github.io/articles/nuttx?3#boot-nuttx

"Hello World" on #BL602 #NuttX ... Looks just like Linux!

https://lupyuen.github.io/articles/nuttx?4#hello-demo

Accessing the System Timer on #NuttX #BL602 ... Everything is a file!

https://lupyuen.github.io/articles/nuttx?5#timer-demo

How we configure the #NuttX Build for #BL602

https://lupyuen.github.io/articles/nuttx?6#configure-nuttx

How we enable "help" and "ls" in #NuttX #BL602

https://lupyuen.github.io/articles/nuttx?7#enable-help-and-ls