ROM API Param structure

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 18, 2016 by lpcware
Content originally posted in LPCWare by fmiku on Wed Mar 02 04:38:42 MST 2016

I have a question about the XXX_PARAM_T structures.

When I using a interrupt driven functions like "LPC_UARTD_API->uart_get_line(HostUartHandle, &param)"
the param structure's data must be keep until the "Done" callback functions are called ?

or the ROM functions makes a own copy of these data into the "xxxHandleMEM[];"

so my problem is the following:

I using the following function to start a UART transmission.

static void host_start_tx (uint8_t *buff, uint16_t size)
    UART_PARAM_T param;

    param.buffer = buff;
    param.size = Txsz = size;

    /* Interrupt mode, do not append CR/LF to sent data */
    param.transfer_mode = TX_MODE_BUF_EMPTY;
    param.driver_mode = DRIVER_MODE_INTERRUPT;

    /* Setup the transmit callback, this will get called when the
       transfer is complete */
    param.callback_func_pt = (UART_CALLBK_T) HostTxCB;

    /* Transmit the data using interrupt mode, the function will
       return */
    if (LPC_UARTD_API->uart_put_line(HostUartHandle, &param)) {
// deinit here ??

Most of time works fine but somtime the transmitted data become corrupted.

I Traced a little in the debugger, some of the params's parameters (CB fns, etc) are  seems to be copied to the UARTHandleMEM[] by the ROM API calls but some like data pointer is not.

so in this case the UART_PARAM_T must be allocated in the global RAM space ?

In this case after calling the ROM api the param structure's data may become "unknow/corrupted" because the variable is created on the stack when the function was called, and released when the controll leaves the function.

I have similatr problem with the I2C ROM api too :)