/* =========================
* ===== Sercom UART
* =========================
*/
void SERCOM::initUART(SercomUartMode mode, SercomUartSampleRate sampleRate, uint32_t baudrate)
{
initClockNVIC();
resetUART();
//Setting the CTRLA register
sercom->USART.CTRLA.reg = SERCOM_USART_CTRLA_MODE(mode) |
SERCOM_USART_CTRLA_SAMPR(sampleRate);
//Setting the Interrupt register
sercom->USART.INTENSET.reg = SERCOM_USART_INTENSET_RXC | //Received complete
SERCOM_USART_INTENSET_ERROR; //All others errors
if ( mode == UART_INT_CLOCK )
{
uint16_t sampleRateValue;
if (sampleRate == SAMPLE_RATE_x16) {
sampleRateValue = 16;
} else {
sampleRateValue = 8;
}
// Asynchronous fractional mode (Table 24-2 in datasheet)
// BAUD = fref / (sampleRateValue * fbaud)
// (multiply by 8, to calculate fractional piece)
uint32_t baudTimes8 = (SystemCoreClock * 8) / (sampleRateValue * baudrate);
sercom->USART.BAUD.FRAC.FP = (baudTimes8 % 8);
sercom->USART.BAUD.FRAC.BAUD = (baudTimes8 / 8);
}
}
/* =========================
* ===== Sercom UART
* =========================
*/
void SERCOM::initUART(SercomUartMode mode, SercomUartSampleRate sampleRate, uint32_t baudrate)
{
#if (SAML21)
// On the SAML21, SERCOM5 is on PD0, which is a low power domain on a different bridge than the other SERCOMs.
// SERCOM5 does not support SAMPLE_RATE_x8 or SAMPLE_RATE_x3.
if (sercom == SERCOM5) {
sampleRate = SAMPLE_RATE_x16;
}
#endif
initClockNVIC();
resetUART();
//Setting the CTRLA register
sercom->USART.CTRLA.reg = SERCOM_USART_CTRLA_MODE(mode) |
SERCOM_USART_CTRLA_SAMPR(sampleRate);
//Setting the Interrupt register
sercom->USART.INTENSET.reg = SERCOM_USART_INTENSET_RXC | //Received complete
SERCOM_USART_INTENSET_ERROR; //All others errors
if ( mode == UART_INT_CLOCK )
{
uint16_t sampleRateValue;
if (sampleRate == SAMPLE_RATE_x16) {
sampleRateValue = 16;
} else {
sampleRateValue = 8;
}
#if 0
// Asynchronous arithmetic mode
// 65535 * ( 1 - sampleRateValue * baudrate / SercomClock);
// 65535 - 65535 * (sampleRateValue * baudrate / SercomClock));
// sercom->USART.BAUD.reg = 65535.0f * ( 1.0f - (float)(sampleRateValue) * (float)(baudrate) / (float)(SercomCoreClock)); // this pulls in 3KB of floating point math code
// make numerator much larger than denominator so result is integer (avoid floating point).
uint64_t numerator = ((sampleRateValue * (uint64_t)baudrate) << 32); // 32 bits of shifting ensures no loss of precision.
uint64_t ratio = divide64(numerator, SercomClock);
uint64_t scale = ((uint64_t)1 << 32) - ratio;
uint64_t baudValue = (65536 * scale) >> 32;
sercom->USART.BAUD.reg = baudValue;
#endif
// Asynchronous fractional mode (Table 24-2 in datasheet)
// BAUD = fref / (sampleRateValue * fbaud)
// (multiply by 8, to calculate fractional piece)
uint32_t baudTimes8 = (SercomClock * 8) / (sampleRateValue * baudrate);
sercom->USART.BAUD.FRAC.FP = (baudTimes8 % 8);
sercom->USART.BAUD.FRAC.BAUD = (baudTimes8 / 8);
}
/* =========================
* ===== Sercom UART
* =========================
*/
void SERCOM::initUART(SercomUartMode mode, SercomUartSampleRate sampleRate, uint32_t baudrate)
{
initClockNVIC();
resetUART();
//Setting the CTRLA register
sercom->USART.CTRLA.reg = SERCOM_USART_CTRLA_MODE(mode) |
SERCOM_USART_CTRLA_SAMPR(sampleRate);
//Setting the Interrupt register
sercom->USART.INTENSET.reg = SERCOM_USART_INTENSET_RXC | //Received complete
SERCOM_USART_INTENSET_ERROR; //All others errors
if ( mode == UART_INT_CLOCK )
{
uint16_t sampleRateValue ;
if ( sampleRate == SAMPLE_RATE_x16 )
{
sampleRateValue = 16 ;
}
else
{
if ( sampleRate == SAMPLE_RATE_x8 )
{
sampleRateValue = 8 ;
}
else
{
sampleRateValue = 3 ;
}
}
// Asynchronous arithmetic mode
// 65535 * ( 1 - sampleRateValue * baudrate / SystemCoreClock);
// 65535 - 65535 * (sampleRateValue * baudrate / SystemCoreClock));
sercom->USART.BAUD.reg = 65535.0f * ( 1.0f - (float)(sampleRateValue) * (float)(baudrate) / (float)(SystemCoreClock));
}
}
