liyanboy74 / soft-uart Goto Github PK

Hello, help me please. I use STM32F103C8T6 blue pill, i configured timer and soft uart. I'm trying send message, but it isn't work, for example, after HAL_TIM_Base_Start_IT(&htim3); the code is not executed

If I understand correctly, the code fires interrupts at a constant frequency, during which you sample the inputs, detect start bits, determine the time slot (0..4) for reading the data bits on a given input, and send if there is outgoing data.

This is different from other implementations which have an interrupt triggered by the edge of the start bit (not a timer) and then read data via a timer interrupt set up when the start bit is detected to hit exactly the middle of the data bits.

In your implementation, you get the benefit of many inputs at the cost of timing accuracy, since you will not sample in the middle of the data bit but rather at the fixed time slot that's closest to it. So the higher the oversampling, the closer you get to that middle.

(did I understand everything correctly?)

Now my question is: how did you get to factor 5x for oversampling? why that number? Let's say you did 3x oversampling, would that not be good enough? Did you do calculations on how much the frequencies can deviate from the ideal value while still sampling the correct bit?

so:
SU_Timer++;
if(SU_Timer >= 5){
SU_Timer=0;
}

then . set the 5 is ??? isn't ?

Can you help me with the issue when I want to be ready to receive with external interrupts on Rx_Pin?