STM32103 bluepill bare-metal WS2812b neopixel driver no libraries

[mytechnotalent]

I have spent a few weeks reviewing HAL related and LL related neopixel libs however I would love if there was someone who had a working version of literally just the ability to set up a neopixel on any port and simply light it or light a few neopixels in an array.

I have found several with HALs but it really does not give a good understanding of how this is done from scratch.

To be clear I am not looking for a HAL solution. I am looking for a bare-metal no library solution.

Thank you in advance.

[gbm]

The first snippet was for SPI, the second is for timer PWM output - it's written in the text. Some convenient #defines from my own header files are used in the code to make it easier to read - they are quite easy to guess.

[mytechnotalent]

#define WSDMA	DMA1
#define WSDMACH	DMA1_Channel1
#define	DMA_IFCR_CGIF_WS	DMA_IFCR_CGIF1
#define WSTIM_CCR	TIM1->CCR1

DMA_IFCR_CGIF1 I assume this is SPI1?

TIM1->CCR1 I assume this is PWM?

[mytechnotalent]

#define WSDMA	DMA1
#define WSDMACH	DMA1_Channel1
#define	DMA_IFCR_CGIF_WS	DMA_IFCR_CGIF1
#define WSTIM_CCR	TIM1->CCR1

I assume DMA_Channel1 is SPI1? I do not see where you are selecting a specific SPI and PWM output.

It is not obvious what pin you are using as I know in the datasheet I have to see where SPI1 can be mapped to but I do not see it here.

[mytechnotalent]

Nevermind I got it to work. Just took some time. Thank you!

[namero999]

I know this is an old thread, but I'm struggling to get anything to work on a STM32G030J6M6, I want to drive a number of smd ws2812. Is there maybe any code you could share if you got it working? Or maybe could you share the many HAL examples that you mentioned?

Thanks!!

[gbm]

This is my code for G030 using UART with 7-bit frames, MSB first, used in my Christmas star.

int main(void)
{
	RCC->PLLCFGR = RCC_PLLCFGR_PLLMV(1) | RCC_PLLCFGR_PLLNV(9) | RCC_PLLCFGR_PLLRV(3)
	| RCC_PLLCFGR_PLLREN | RCC_PLLCFGR_PLLSRC_HSI;	// 
	RCC->CR |= RCC_CR_PLLON;	// turn PLL on
	while (!(RCC->CR & RCC_CR_PLLRDY));	// wait for PLL lock
	FLASH->ACR |= FLASH_ACR_PRFTEN | 1;	// enable prefetch, 1 wait state
	RCC->CFGR |= RCC_CFGR_SW_PLLRCLK;	// switch to PLL clock
	
	RCC->IOPENR |= RCC_IOPENR_GPIOAEN | RCC_IOPENR_GPIOBEN;
	RCC->AHBENR |= RCC_AHBENR_DMA1EN;
	RCC->APBENR2 = RCC_APBENR2_USART1EN;
	
	// the UART may also work with 8-bit frames, this requires shifting the data by one to the left (verified)
	WS_UART->BRR = (HCLK_FREQ + WSBAUD / 2) / WSBAUD;
	WS_UART->CR2 = USART_CR2_TXINV | USART_CR2_MSBFIRST | USART_CR2_DATAINV | USART_CR2_SWAP;
	WS_UART->CR3 = USART_CR3_DMAT;
	WS_UART->CR1 = USART_CR1_M1 | USART_CR1_TE | USART_CR1_UE;
	
	WS_DMACH->CPAR = (uint32_t)&WS_UART->TDR;
	
	GPIOB->MODER = BF2(7, GPIO_MODER_AF);	// USART1
	
	DMAMUX1_Channel0->CCR = DMAREQ_ID_USART1_TX;
	
	SysTick_Config(HCLK_FREQ / SYSTICK_FREQ);
	
	for (;;)
		__WFI();
}

struct rgb_ {
	uint8_t r, g, b;
};

struct rgb_ lc[NLEDS];
static uint8_t txbuf[NLEDS * 8];

void encode(uint8_t *encbuf, const struct rgb_ *img, uint16_t nleds)
{
	// MSB-first encoding table
	static const uint8_t uenc[] = {
		0000 | 022, 0001 | 022, 0010 | 022, 0011 | 022,
		0100 | 022, 0101 | 022, 0110 | 022, 0111 | 022
	};

	for (uint16_t i = 0; i < nleds; i++)
	{
		uint32_t v = img[i].r | img[i].g << 8 | img[i].b << 16;
		for (uint8_t b = 0; b < 8; b++)
		{
			*encbuf++ = uenc[v >> 21 & 7];
			v <<= 3;
		}
	}
}

void ws_start(void)
{
	encode(txbuf, lc, NLEDS);
	
	WS_DMACH->CCR = 0;
	WS_DMACH->CMAR = (uint32_t)txbuf;
	WS_DMACH->CNDTR = sizeof(txbuf);
	WS_DMACH->CCR = DMA_CCR_DIR_M2P | DMA_CCR_MINC | DMA_CCR_EN;
}