Hello!

Thank you very much for your response, it made a lot of sense.

I went through and modified those files but now I get this compilation error:

BurstSPI_STM32F4.cpp:6:48: error: invalid cast from type 'spi_s' to type 'SPI_TypeDef*'

Try to modify BurstSPI_STM32F4.cpp as below:

#if defined(TARGET_STM32F4) 

#include "BurstSPI.h"
 
void BurstSPI::fastWrite(int data) {    
    SPI_TypeDef *spi = (SPI_TypeDef *)(_spi.spi);
    // Check if data is transmitted
    while ((spi->SR & SPI_SR_TXE) == 0);
    spi->DR = data;
}
    
void BurstSPI::clearRX( void ) {
    //Check if the RX buffer is busy
    SPI_TypeDef *spi = (SPI_TypeDef *)(_spi.spi);
    //While busy, keep checking
    while (spi->SR & SPI_SR_BSY){   
        // Check RX buffer readable
        while ((spi->SR & SPI_SR_RXNE) == 0);
        int dummy = spi->DR;
    }
}

#elif defined(TARGET_STM32F1)

#include "BurstSPI.h"
 
void BurstSPI::fastWrite(int data) {  
    SPI_TypeDef *spi = (SPI_TypeDef *)(_spi.spi.handle.Instance);
    // Check if data is transmitted
    while ((spi->SR & SPI_SR_TXE) == 0);
    spi->DR = data;
}
    
void BurstSPI::clearRX( void ) {
    //Check if the RX buffer is busy
    SPI_TypeDef *spi = (SPI_TypeDef *)(_spi.spi.handle.Instance);
    //While busy, keep checking
    while (spi->SR & SPI_SR_BSY){   
        // Check RX buffer readable
        while ((spi->SR & SPI_SR_RXNE) == 0);
        int dummy = spi->DR;
    }
}

#endif

I found this issue on BurstSPI: https://os.mbed.com/users/Sissors/code/BurstSPI/issues/2

I ended trying both suggestions: SPI_TypeDef *spi = reinterpret_cast<SPI_TypeDef*&>(_spi.spi); SPI_TypeDef *spi = _spi.spi.handle.Instance;

To no success :(

Oopps posted before I saw your reply!

I tried that as well and no success :/

I have used a logic analyser to check the output

Before I modified BurstSPI_STM32F4.cpp I was getting some sort of output But since nothing is appearing...

May we see your application code to understand how you send data? NOTE: To keep the format after pasting it to the edit box use tags as below.

<<code>>
Code of your program.
<</code>>

Yes of course,

here is my code (used some examples found on this site)

#include <mbed.h>
#include <neopixel.h>

#define NUM_LEDS        8
#define LED_PIN         PB_15


void setPixel(neopixel::Pixel * buffer, uint32_t index, uint8_t red, uint8_t green, uint8_t blue, uint32_t length)
{
    if (index >= length ) {
        return;
    }
    buffer[index].red = red;
    buffer[index].green = green;
    buffer[index].blue = blue;
}

int main() {

    // Create a temporary DigitalIn so we can configure the pull-down resistor.
    // (The mbed API doesn't provide any other way to do this.)
    // An alternative is to connect an external pull-down resistor.
    DigitalIn(LED_PIN, PullDown);

    // The pixel array control class.
    neopixel::PixelArray array(LED_PIN);
    neopixel::Pixel buffer[NUM_LEDS];

    while (1) {
        // All LEDs on
        for (int i = 0; i < NUM_LEDS; ++i) {
            setPixel(buffer, i,0xFF, 0xFF, 0xFF, NUM_LEDS);
        }

        array.update(buffer, NUM_LEDS);
        wait_ms(1000);

    }
    
}

Hello Jim, Since the length of my response is limited to max 3000 characters a I was not able to add new code here. So I modified my original answer. I hope that this time it will do the job.

Hello Zoltan, thank you very much for taking the time to answer and respond to this issue. I have tried your modified code in the original answer, and BurstSPI::fastWrite compiles with no issue, except it is still hanging on:

.piolibdeps/BurstSPI_ID2973/BurstSPI_STM32F4.cpp:84:52: error: invalid cast from type 'spi_s' to type 'SPI_TypeDef*'

in BurstSPI::clearRX

I'm sorry. It should compile now and I was able to see some pulses at the SPI MOSI pin with my logic analyzer.

Hello Zoltan, thanks a lot for your time on this matter. I was now able to compile! (On both the online Mbed compiler and my offline mbed setup)

I uploaded the code onto my board and it doesn't work :/ I hooked it up to my logic analyser and the timings are off. I used the code I posted above, plus the example code provided with the PixelArray library. Nothing worked. I tried using the online MBed compiler and my offline setup, no dice.

I think with the amount of hours I have put in trying to get this simple example to work, it has killed quite a bit of my motivation for mbed at the moment. I have been testing this framework recently and seemingly simple things turn out to be complicated. (I will come back to mbed again, as the concept does interest me and to practise and learn a framework that should be able to be applied to numerous devices - I might need to start on more simple examples than WS2812 LEDs ;D even though I find this to be a good example for testing out timings on MCUs)

I'll revert to another framework for the time being as I really wish to get one of my test ideas into a project and bring back some of that MCU fun.

As the code compiles with no errors, I have accepted your answer Zoltan, maybe someone else with a bit more know-how than myself with MBed will be able to get this working on the F103.

Thanks again for your time as otherwise I would have been even more lost

(as an aside the online MBed compiler also acts a bit odd... I imported the PixelArray library and it imported BurstSPI automatically but conveniently leaves out the BurstSPI_Unsupported.cpp and BurstSPI_STM32F4.cpp O.O probably because I only have a F103 board setup in the config but anyway... not very helpful when it includes all the other files for other boards instead...)