Lup Yuen Lee 李立源 @lupyuen@qoto.org

Now our #NuttX App is ready to read an SX1262 Register over SPI!

https://github.com/lupyuen/incubator-nuttx-apps/blob/spi_test/examples/spi_test2/spi_test2_main.c#L90-L119

Here's our #NuttX App controlling SPI Chip Select via GPIO

https://github.com/lupyuen/incubator-nuttx-apps/blob/spi_test/examples/spi_test2/spi_test2_main.c#L42-L74

#BL602 SPI Chip Select has a problem ... It goes High after EVERY byte ... Which is no-no for SX1262 ... Solution: We control Chip Select via GPIO

https://github.com/lupyuen/incubator-nuttx-apps/blob/spi_test/examples/spi_test2/spi_test2_main.c#L42-L74

Our #NuttX App transmits an SPI Command to SX1262 ... And reads the SPI Response from SX1262

https://github.com/lupyuen/incubator-nuttx-apps/blob/spi_test/examples/spi_test2/spi_test2_main.c#L54-L84

We implement the Read Operation for our #NuttX SPI Driver ... So that we can fetch the SPI Response from SX1262

https://github.com/lupyuen/incubator-nuttx/blob/spi_test/drivers/rf/spi_test_driver.c#L210-L233

Let's test #NuttX SPI with #BL602 and Semtech SX1262 LoRa Transceiver

https://www.semtech.com/products/wireless-rf/lora-core/sx1262

After swapping #BL602 MISO and MOSI at #NuttX startup ... Logic Analyser shows that the SPI Pins are now consistent with BL602 Reference Manual! 🎉

https://github.com/lupyuen/incubator-nuttx/blob/swap_miso_mosi/arch/risc-v/src/bl602/bl602_spi.c#L1080-L1140

Here's how we swap #BL602 MOSI and MISO on #NuttX ... So that the SPI Pins are consistent with the BL602 Reference Manual

https://github.com/lupyuen/incubator-nuttx/blob/swap_miso_mosi/arch/risc-v/src/bl602/bl602_spi.c#L1080-L1140

Yep it works fine with #BL602 Firmware 👍

#PineDio Stack #BL604 now comes with an interesting Baseboard 🤔

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