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Lup Yuen Lee 李立源

Transmitter ... Sniffed by Airspy R2 SDR ... Watch the distinctive LoRa Chirp (red spike)

youtu.be/USqStub3KC0

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Lup Yuen Lee 李立源

When transmits Packets ... Our LoRa Receiver hangs! ... Let's find out why 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Maybe is stuck forever handling Packet Received Interrupts? 🤔 ... Let's suppress GPIO Interrupts after handling the first 5 interrupts

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

And still hangs when transmits Packets ... Chaos Magic 🤔

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Lup Yuen Lee 李立源

Something spooky about GPIO Interrupts 🤔 ... Let's disconnect SX1276 pins DIO1 to DIO3 ... And connect DIO0 to my fav Blue LED (GPIO 11)

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Blue LED switches off ... When transmits a Packet ... So DIO0 Packet Received works! Why does the GPIO Interrupt hang? 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

GPIO Interrupt triggered OK when Packet received yay! ... But why does it work now? 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

GPIO Interrupts hanging could be due to the way we handle multiple GPIO Interrupts ... Let's revisit this when we can trigger multiple GPIO Interrupts from SX1276

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Now that can handle Packet Received Interrupt ... Let's defer the LoRa Packet Processing from the Interrupt Handler to the Application Task ... How shall we do this in FreeRTOS? 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Maybe can help ! ... The NimBLE Porting Layer defines Multitasking Functions for ... Let's call them to handle Interrupts

lupyuen.github.io/pinetime-rus

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Lup Yuen Lee 李立源

NimBLE Porting Layer hasn't been ported ... To ? 🤔 ... Let's fix this for

github.com/apache/mynewt-nimbl

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Lup Yuen Lee 李立源

Fortunately has a function to check whether we're in a Interrupt Handler ... "xPortIsInsideInterrupt"

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

NimBLE Porting Layer builds OK on yay! ... Let's call these Event Queue functions to process our received Packets

lupyuen.github.io/pinetime-rus

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Lup Yuen Lee 李立源

Multitasking made easier with NimBLE Porting Library ... Here's how we create an Event Queue ... And add an Event to the queue

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Now we handle Events from the Event Queue ... Multitasking made easier with NimBLE Porting Library

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

NimBLE Porting Library works great on ... Multitasking made easier!

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Shall we teach Multitasking with NimBLE Porting Layer? 1️⃣ Looks easier than FreeRTOS 2️⃣ It's portable to FreeRTOS, Mynewt, NuttX and RIOT OS 🤔

lupyuen.github.io/pinetime-rus

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Lup Yuen Lee 李立源

Let's use the Event Queue to forward the Packet Received Interrupt ... From Interrupt Handler ... To the Application Task

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Packet goes from Transmitter ... To SX1276 Interrupt Handler ... To Task yay! Now we read the received LoRa Packet from SX1276 over SPI

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Aha! hits a Exception ... When processing the received Packet! Let's follow these steps to troubleshoot...

lupyuen.github.io/articles/i2c

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Lup Yuen Lee 李立源

Our Build, Flash and Run Firmware script generates the Disassembly ... Let's track down the address of the RISC-V Exception

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Oops the Program Counter for our Exception is null ... So there must be a missing Callback Function somewhere in our Firmware 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Exception happened because we passed a pointer to a stack object ... Which gets used by the Interrupt Handler 😲 ... This works OK in the original Mynewt code, but not for BL602

gist.github.com/lupyuen/1539f9

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Lup Yuen Lee 李立源

For we fix this exception by copying the object ... Instead of storing a pointer to the object

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

now displays the Packet received from yay!

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Mystery GPIO Function ... What does it do? Will it fix our problem with triggering multiple GPIO Interrupts? 🤔

github.com/bouffalolab/bl_iot_

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Lup Yuen Lee 李立源

Reference Manual mentions "GPIO_INT_CLR" but the address is undefined in the doc ... Methinks a chunk of addresses are missing from the doc 🤔

github.com/bouffalolab/bl_docs

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Lup Yuen Lee 李立源

Searching GitHub for "GPIO_INT_CLR" shows ultraembedded RISC-V SoC ... Coincidence? 🤔

github.com/search?l=Markdown&q

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Lup Yuen Lee 李立源

Ah my folly ways ... Multiple GPIO Interrupts can't be registered like this ... Lemme fix this 🪠

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

supports only one Interrupt Handler for all GPIO Pins ... Let's iterate thru the SX1276 Interrupts and handle them

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

now detects Multiple GPIO Interrupts ... Triggered by SX1276 yay!

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Let's handle GPIO Interrupts the smarter way ... By iterating thru the Interrupt Events created with the NimBLE Porting Layer

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Reconnected @PINE64 ... To SX1276 pins DIO0 to DIO3 ... For testing our GPIO interrupt handler

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Enabled GPIO Interrupt Handler for SX1276 ... And BL602 hits a Exception ... At an invalid Program Address 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Let's disable Channel Activity Detection for now ... receives first LoRa Packet ... But not the second packet 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Never clear the GPIO Interrupt Status! 🚧 ... This suppresses subsequent GPIO Interrupts 😲 ... We can now receive multiple Packets yay!

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Can show the Stack Trace for this Exception? ... Let's find out 🤔

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Stack Trace Hieroglyphics ... Can we use this to dump the Stack Trace for our Exception? 🤔

github.com/bouffalolab/bl_iot_

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Lup Yuen Lee 李立源

Here's the Exception Handler ... Seems capable of showing the Stack Trace 🤔

github.com/bouffalolab/bl_iot_

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Lup Yuen Lee 李立源
Follow

shows Stack Trace when CONFIG_ENABLE_FP=1 ... But the addresses don't make sense ... They belong to the code that's dumping the Stack Trace 🤔

github.com/lupyuen/bl_iot_sdk/

· · Tusky · 1 · 0 · 0
Lup Yuen Lee 李立源

Oops needs us to "make clean ; make" to fix up the Stack Frame Pointers ... Now BL602 Stack Trace points to the "ebreak" instruction ... Which belongs to the Exception Handler 🙄

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Deciphering the Stack Trace Hieroglyphics ... There must be a way to get the Stack Frame before our Exception 🤔

github.com/bouffalolab/bl_iot_

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Lup Yuen Lee 李立源

Stack Trace always shows the Current Stack ... Let's show the stack before hitting the Exception

github.com/bouffalolab/bl_iot_

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Lup Yuen Lee 李立源

Let's dump the Stack with this function ... And figure out why our Exception Stack Trace doesn't look right

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Here are the Stacks for the Foreground RTOS Task, Background Task and Exception Handler ... Let's see what's wrong with the Exception Stack

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Complete Stack Data for the Exception is here

gist.github.com/lupyuen/5ddbcd

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Lup Yuen Lee 李立源

Below the Exception Handler Stack ... Is another Stack! ... Does this Stack contain the Stack Trace that we need? 🤔

gist.github.com/lupyuen/5ddbcd

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Lup Yuen Lee 李立源

Quiz: What's wrong with this C code? 🤔 ... I'm soooo upset I missed this simple bug 🙄

github.com/apache/mynewt-core/

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Lup Yuen Lee 李立源

Answer: "radio_events" contains Undefined Fields ... Because it was allocated on the Stack! Lesson Learnt: ALWAYS Init Stack Variables! 🙏

github.com/apache/mynewt-core/

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Lup Yuen Lee 李立源

Here's how we fixed the Exception for Channel Activity Detection ... Always init Stack Variables! 🙏

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Back to our Stack Trace ... Yep the Correct Stack Trace is indeed lurking behind our (unhelpful) Exception Stack Trace ... How shall we show the Correct Stack Trace beyond the Emptiness? 🤔

gist.github.com/lupyuen/5ddbcd

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Lup Yuen Lee 李立源

@PINE64 receives Packets from RAKwireless ... Almost finished! One more thang ...

youtu.be/3TSvo0dwwnQ

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Lup Yuen Lee 李立源

To conserve battery power, Sensors don't always listen for incoming packets ... They listen for a few seconds then go back to sleep. 😴 LoRa Receive Timeout is the last thing we shall implement for

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Let's do Receive Timeout with these Callout Functions from the NimBLE Porting Layer

lupyuen.github.io/pinetime-rus

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Lup Yuen Lee 李立源

Here are the Timer Functions that we shall implement with NimBLE Porting Layer

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

receives 4 Packets by executing 458 SPI requests ... Great load test for SPI 👍

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Driver creates hundreds of SPI DMA Requests ... Each request reads / writes only ONE byte! 🙄 ... Note to future self: Combine the SPI DMA Requests

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

@PINE64 connected to SX1276 / RF96 Transceiver ... Including pins DIO0 to DIO3

github.com/lupyuen/bl_iot_sdk/

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Lup Yuen Lee 李立源

Timers for Driver ... Implemented with NimBLE Porting Layer

github.com/lupyuen/bl_iot_sdk/

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🎓 Doc Freemo :jpf: 🇳🇱

@lupyuen wow, that is some crappy implementation by the sound of it! Honestly I am surprised, usually the low-level uC people (the ones working with assembly and C) tend to do a way better job than that.

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Lup Yuen Lee 李立源

@freemo Haha ahem ... I ported this LoRa driver from Mynewt OS. The driver was designed for platforms without DMA.

Since we support DMA on BL602, we can do better ... But the driver needs to be redesigned.

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░▒▓█►─═ 𐌔Ꝋ𐌂𐌊𐌔 𐌐𐌓Ꝋ𐋄𐌙 𓂀 ═─◄█▓▒░

@lupyuen
What hw part is being talked to over said dma? Does order of dma reads matter? Can you cache requests issue dma read burst and send result asynchronously etc or per queue keeping order? We had similar problem in nokia on radiomodules i think. Dont remember exact solution though.

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Lup Yuen Lee 李立源

@PawelK I ported the driver from Mynewt OS to BL602.

Since I don't have the time to redesign the driver and do a thorough regression test ... We'll have to live with this inefficiency for now.

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Blort™ 🐀Ⓥ🥋☣️

@lupyuen yeesh!

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░▒▓█►─═ 𐌔Ꝋ𐌂𐌊𐌔 𐌐𐌓Ꝋ𐋄𐌙 𓂀 ═─◄█▓▒░

@lupyuen
Yes uninit vars suck. Llvm/clang autowarns or can error on this. Has great static checker too and plenty of warnings etc.

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░▒▓█►─═ 𐌔Ꝋ𐌂𐌊𐌔 𐌐𐌓Ꝋ𐋄𐌙 𓂀 ═─◄█▓▒░

@lupyuen
Use before def/partial def only.

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