Lup Yuen Lee 李立源 @lupyuen@qoto.org

Yep it's an updated #PineDio Stack BL604 @PINE64 ... With LoRa SX1262!

https://lupyuen.github.io/articles/pinedio

We can swap MISO and MOSI on #BL602 by setting a Hardware Register ... Let's do this on #NuttX

https://lupyuen.github.io/articles/pinedio#spi-pins-are-swapped

Logic Analyser connected to #BL602 shows that MISO and MOSI are swapped! This happens in BL602 IoT SDK ... Also in #NuttX!

https://lupyuen.github.io/articles/spi#spi-data-pins-are-flipped

#NuttX's SPI Pins match the #BL602 Reference Manual: MOSI = GPIO 1, MISO = GPIO 0 ... But we're about to witness a BL602 SPI Quirk

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

In #NuttX the SPI Pins for #BL602 are defined in "board.h" ... MOSI is GPIO 1, MISO is GPIO 0

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/boards/risc-v/bl602/bl602evb/include/board.h#L87-L92

How to verify the #NuttX SPI Output? We sniff the #BL602 SPI Bus with a Logic Analyser

https://lupyuen.github.io/articles/spi#appendix-troubleshoot-bl602-spi-with-logic-analyser

Now we see every byte transferred by #NuttX's SPI Driver for #BL602!

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/drivers/rf/spi_test_driver.c

To watch what happens inside #NuttX's SPI Driver for #BL602 ... Turn on SPI Debug Logging

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/arch/risc-v/src/bl602/bl602_spi.c

Here's how we configure the #NuttX SPI Interface

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/drivers/rf/spi_test_driver.c#L95-L117

In the write() operation for our #NuttX SPI Test Driver, we 1️⃣ Lock the SPI Bus 2️⃣ Config the SPI Interface 3️⃣ Select the SPI Device 4️⃣ Transfer SPI Data 5️⃣ Deselect and Unlock

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/drivers/rf/spi_test_driver.c#L182-L239

Every #NuttX Device Driver defines the File Operations for the device ... Here are the open(), close(), read(), write() and ioctl() operations for our SPI Test Driver

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/drivers/rf/spi_test_driver.c#L80-L89

This appears when we run our #NuttX SPI Test App ... Let's study our SPI Test Driver

https://github.com/lupyuen/incubator-nuttx-apps/blob/spi_test/examples/spi_test/spi_test_main.c

Splotchy Sky in Sunny Singapore

Back to our #NuttX SPI Test App ... Here's how we open the SPI Test Driver and write data

https://github.com/lupyuen/incubator-nuttx-apps/blob/spi_test/examples/spi_test/spi_test_main.c

Build, flash and run #NuttX ... Our SPI Test Driver appears as "/dev/spitest0"! 🎉

https://github.com/lupyuen/incubator-nuttx/blob/newdriver/drivers/rf/spi_test_driver.c

Update the Makefile "Make.defs" ... So that #NuttX will build our SPI Test Driver

https://github.com/lupyuen/incubator-nuttx/blob/newdriver/drivers/rf/Make.defs#L33-L37

Here's what happens when we make a boo-boo and #NuttX won't start

https://gist.github.com/lupyuen/ccfd90125f9a180b4cfb459e8a57b323

Remember to enable "SPI0" and "SPI Character Driver" in #NuttX ... Or our SPI Test Driver won't start

https://github.com/lupyuen/incubator-nuttx/blob/newdriver/drivers/rf/spi_test_driver.c

Our SPI Test Driver for #NuttX appears in "make menuconfig"!

https://github.com/lupyuen/incubator-nuttx/blob/newdriver/drivers/rf/Kconfig#L22-L27

Add our SPI Test Driver to #NuttX Kconfig

https://github.com/lupyuen/incubator-nuttx/blob/newdriver/drivers/rf/Kconfig#L22-L27