topic Beekit Kinetis uart.c error in Kinetis Microcontrollers

Beekit Kinetis uart.c error

john5 — Wed, 13 May 2015 13:50:08 GMT

I've been writing a function for a MK21D256 project that uses uart1 (or uart2) in two different baudrate/parity configurations.

The uart is initially configured at 38400/noparity, then later switches to 9600/evenparity. All good so far.

Then I switch back to 38400/noparity, but the baud rate is set incorrectly.

The error lies in function

UartErr_t UartSetConfig( uint8_t UartNumber, UartConfig_t* pConfig );

in the section that calculates and sets uartregs->BDH and uartregs->BDL.

Here is the fix.

#if (1) -

mUartModule[UartNumber].UartRegs->BDH = (uint8_t)((mUartSBR >> 8) & gUART_BDH_MASK_c); // this code works

mUartModule[UartNumber].UartRegs->BDL = (uint8_t) (mUartSBR & gUART_BDL_MASK_c); //---------------------

#else // (1)

// when BDH is written the value is buffered and only applied when BDL is written

// the two writes to BDH here mess that requirement up ie the 0x00 does not get written, so the previous value is not zeroed.

mUartModule[UartNumber].UartRegs->BDH = 0x00;

mUartModule[UartNumber].UartRegs->BDH |= (uint8_t)((mUartSBR >> 8) & gUART_BDH_MASK_c);

mUartModule[UartNumber].UartRegs->BDL = (uint8_t) (mUartSBR & gUART_BDL_MASK_c);

#endif // (1)

That took quite a while to find - i.e. I assumed that the Freescale code was sacrosanct.

John

Re: Beekit Kinetis uart.c error

Hui_Ma — Thu, 14 May 2015 03:29:06 GMT

Hi John,

The original code without clear the previous value and just add the register bits, which cause the issue.

I will forward this info to related team. Thank you for the info.

Have a great day,
Ma Hui

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Re: Beekit Kinetis uart.c error

john5 — Fri, 15 May 2015 02:05:05 GMT

Hi Hui Ma,

Also, have discovered an error in uart.h relating to using 8 bit data, with parity. The error was discovered in 3.0.1 and is still in projects generated using 3.0,2 :

/* Data bits mask */

#define gUART_DATA_BITS_BIT_c (0x8u)

That should be

/* Data bits mask */

#define gUART_DATA_BITS_BIT_c (0x10u)

Thats the UARTX_C1.M bit setting, It currently incorrectly sets the UARTX_C1.WAKE bit.

John