Multi Software Serial (UART) For STM32

The library work fine for virtualize 6 UART full duplex in baud rate 9600. All UART work together parallelly!

Library Dir:

• Softuart.h
• Softuart.c

Handler & baud rate

The function SoftUartHandler(void) must call in interrupt every 0.2*(1/BR) .

if BR=9600 then 0.2*(1/9600)=20.8333333 uS

highly recommended set maximum CPU clock for Run Handler faster as possible! you also available for use lite version by limited options for slow MCUs.

The library don't change any GPIO config! before using must config TX pins as output and RX pins as input , any TX pin must set to HIGH and any RX pin must be Pullup.

Example Timer Config

for Baud Rate 9600 :

Config	value
Timer Clock	72 MHz
Prescaler (PSC - 16 bits value)	74
Counter Period (AutoReload Register - 16 bits value )	19
auto-reload preload	Enable
Tim global interrupt	Enable

You also can use Timer frequency calculator.

Calling handler

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
	if(htim->Instance==TIMX)
	{
		SoftUartHandler();
	}
}

Config Soft UART

Open softuart.h and edit bellow line as you want:

#define 	Number_Of_SoftUarts	 6
#define		SoftUartTxBufferSize	32
#define		SoftUartRxBufferSize	64

If Number_Of_SoftUarts=6 that mean you SoftUartNumber is 0,1,2,3,4,5

After config timer for config Soft UART use SoftUartInit:

SoftUartState_E SoftUartInit(uint8_t SoftUartNumber,GPIO_TypeDef *TxPort,uint16_t TxPin,GPIO_TypeDef *RxPort,uint16_t RxPin);

Using Soft UART

Transmit always is Possible but for Receiving data you must enable listening by calling:

SoftUartState_E SoftUartEnableRx(uint8_t SoftUartNumber);

Received data stored in buffer accessible by below functions:

uint8_t 	SoftUartRxAlavailable(uint8_t SoftUartNumber);
SoftUartState_E SoftUartReadRxBuffer(uint8_t SoftUartNumber,uint8_t *Buffer,uint8_t Len);

Transmit data:

SoftUartState_E SoftUartPuts(uint8_t SoftUartNumber,uint8_t *Str,uint8_t Len);
void 		SoftUartWaitUntilTxComplate(uint8_t SoftUartNumber);

Example test:

Transmit

while(1)
{
	SoftUartPuts(0,(uint8_t *)"Hello",5);
	SoftUartPuts(1,(uint8_t *)"My",2);
	SoftUartPuts(2,(uint8_t *)"Name",4);
	SoftUartPuts(3,(uint8_t *)"Is",2);
	SoftUartPuts(4,(uint8_t *)"Esmaeill",8);
	SoftUartPuts(5,(uint8_t *)"--------",8);
}

Receive

Example 1:

uint8_t getchar(uint8_t SoftUartNumber)
{
    uint8_t ch;
    while(SoftUartRxAlavailable(SoftUartNumber)==0);
    SoftUartReadRxBuffer(SoftUartNumber,&ch,1);
    return ch;
}

Example 2:

uint8_t Buffer[SIZE],Len;

while(1)
{
	// Read >= 10 Byte Data if Received
	if(Len=SoftUartRxAlavailable(0),Len>=10)
	{
		// Move Received Data To Another Buffer
		if(SoftUartReadRxBuffer(0,Buffer,Len)==SoftUart_OK)
		{
			// Done
		}
	}
}

Full Example 3:

#include "softuart.h"

...

void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
	if(htim->Instance == TIMX)
	{
		SoftUartHandler();
	}
}

uint8_t getchar(uint8_t SoftUartNumber)
{
    uint8_t ch;
    while(SoftUartRxAlavailable(SoftUartNumber)==0);
    SoftUartReadRxBuffer(SoftUartNumber,&ch,1);
    return ch;
}

int main(void)
{
    uint8_t ch;
    
    ...
    
    HAL_TIM_Base_Start_IT(&htimX);
    
    SoftUartInit(0,SU_TX_GPIO_Port,SU_TX_Pin,SU_RX_GPIO_Port,SU_RX_Pin);
    SoftUartEnableRx(0);
    
    ...
    
    while (1)
    {
        ch=getchar(0);
        SoftUartPuts(0,&ch,1);
        //SoftUartWaitUntilTxComplate(0);
        HAL_GPIO_TogglePin(LED_GPIO_Port,LED_Pin);
    }
}