LL_USART_Init generated by CubeMX size reduction ?

[WGend.15]

Hi everyone,

Like most of embedded work, our project aims to have the smallest size possible.

Looking at what I can optimize, I came across the LL_USART_Init function that is generated by CubeMx.

This function uses LL_USART-SetBaudRate which needs to use Division for unsigned long (_udivmoddi4). On a STM32F4 project, _udivmoddi4 takes 720 bytes of flash space!!

Does anyone have a simple trick to get around this apart from getting rid of CubeMX initialisation and never use LL_USART_SetBaudRate ?

[gbm]

If the target baud rate is constant - just define the clock frequency as a constant (forget the variable) and use constant expression to initialize BRR:

#define USART_CLK 48000000u

#define BAUD_RATE 115200u

USART1->BRR = (USART_CLK + BAUD_RATE / 2) / BAUD_RATE;

USART1->CR1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE;

These two lines are enough for simple UART init, so you may also forget any fancy HAL/LL UART_Init routines.