How to write code that is port flexible? I have a project I want to do that the UARTs used may change by end-user config setting. So it may have communication on one or many UARTs (almost like a matrix scheme). How do I abstract the UART(s)?

[Grant Bt]

I realize this isn't STM32 specific, but that's what I am using. I would like to learn from examples where ports and data are changeable at run-time. I know I need to use a pointer, but I'm not sure how to proceed. So a chunk of code at one boot might write data out UART1, then after user config and next boot, UART2 or both or whatever.

Edit: Preferably there would only be one set of UART functions for initialization, read, write, etc. These would use the appropriate data and hardware depending on the configuration.

[Tesla DeLorean]

The things are instances/objects to start with. The normal approach is to pass around a pointer rather than use a global.

UART_HandleTypeDef Uart[1] = {0};

void InitUart(UART_HandleTypeDef *UartInstance, USART_TypeDef *Uart, uint32_t BaudRate)

{

 UartInstance->Instance       = Uart;

 UartInstance->Init.BaudRate  = BaudRate;

 UartInstance->Init.WordLength = UART_WORDLENGTH_8B;

 UartInstance->Init.StopBits  = UART_STOPBITS_1;

 UartInstance->Init.Parity    = UART_PARITY_NONE;

 UartInstance->Init.HwFlowCtl = UART_HWCONTROL_NONE;

 UartInstance->Init.Mode      = UART_MODE_TX_RX;

 UartInstance->Init.OverSampling  = UART_OVERSAMPLING_16;

#ifdef UART_ONE_BIT_SAMPLE_DISABLE

 UartInstance->Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;

#endif

 if (HAL_UART_Init(UartInstance) != HAL_OK)

 {

   /* Initialization Error */

   Error_Handler();

 }

}

void OutString(UART_HandleTypeDef *UartInstance , char *s)

{

 HAL_UART_Transmit(UartInstance, (uint8_t *)s, strlen(s), 5000);

}

InitUart(Uart, USART2, 115200);

OutString(Uart,"Hello World!\n");

[Grant Bt]

Thanks, Yes, this is what I was concerned about. If a process has data it can't just enqueue it Enqueue(theData), it has to pass around the instance as you say, Enqueue(theInterface, theData), so it still needs to specify which Uart. Hmmm. I also have some interfaces that are bit-bang port things, so I want to make it as clean as possible for the higher layers. Like for example, a byte might be going out a UART or USB CDC VCOM or even something else. I don't want to have to have to use switch statements all over the place where it decides at run-time which interface to receive the data.