Hi!
The frequency of USART is not correctly computed in file fsl_clock.c in SDK 2.9.0 for LPC812.
The current code is:
uint32_t CLOCK_GetUartClkFreq(void)
{
uint32_t freq = CLOCK_GetMainClkFreq();
uint32_t uartDiv = SYSCON->UARTCLKDIV & 0xffU;
return uartDiv == 0U ? 0U :
(uint32_t)((uint64_t)(freq << 8U) /
(uartDiv * (256U + ((SYSCON->UARTFRGMULT) & SYSCON_UARTFRGMULT_MULT_MASK))));
}
The variable freq should be retyped to uint64_t before shift left. Better is:
return uartDiv == 0U ? 0U : (uint32_t)((((uint64_t)(freq)) << 8U) /....
It is easy to test it for MainClock 24 MHz, UARTCLKDIV =1 and UARTFRGMULT=0. The correct result should be 24 MHz, but the function returns bad result: 7222784 Hz.
The 24 MHz is 0x16E3600 and after shift left is out of range of uint32_t.
Petr
