USART_ID usartOpen(USART_ID usartId, uint32_t ulWantedBaud, uint16_t uxTxQueueLength, uint16_t uxRxQueueLength )
{
uint8_t * dataPtr;
/* Create the ring-buffers for the USART. */
if( (dataPtr = (uint8_t *)pvPortMalloc( sizeof(uint8_t) * uxRxQueueLength )))
ringBuffer_InitBuffer( &(usartComBuf[usartId].xRxedChars), dataPtr, uxRxQueueLength);
if( (dataPtr = (uint8_t *)pvPortMalloc( sizeof(uint8_t) * uxTxQueueLength )))
ringBuffer_InitBuffer( &(usartComBuf[usartId].xCharsForTx), dataPtr, uxTxQueueLength);
// create a working buffer for vsnprintf on the heap (so we can use extended RAM, if available).
// create the structures on the heap (so they can be moved later).
if( !(usartComBuf[usartId].workBuffer = (uint8_t *)pvPortMalloc( sizeof(uint8_t) * uxTxQueueLength )))
usartComBuf[usartId].workBuffer = NULL;
usartComBuf[usartId].workBufferSize = uxTxQueueLength; // size of the working buffer for vsnprintf
usartComBuf[usartId].workBufferInUse = USART_VACANT; // clear the occupation flag.
portENTER_CRITICAL(); // Disable interrupts during configuration
/*
* Calculate the baud rate register value from the equation in the data sheet. */
/* As the 16MHz Arduino boards have bad karma for serial port, we're using the 2x clock U2X0 */
// for Arduino at 16MHz; above data sheet calculation is wrong. Need below from <util/setbaud.h>
// This provides correct rounding truncation to get closest to correct speed.
// Normal mode gives 3.7% error, which is too much. Use 2x mode gives 2.1% error.
// Or, use 22.1184 MHz over clock which gives 0.00% error, for all rates.
// ulBaudRateCounter = ((configCPU_CLOCK_HZ + ulWantedBaud * 8UL) / (ulWantedBaud * 16UL) - 1); // for normal mode
// ulBaudRateCounter = (uint16_t)((configCPU_CLOCK_HZ + ulWantedBaud * 4UL) / (ulWantedBaud * 8UL) - 1); // for 2x mode
*usartReg[usartId].ubbrPtr = (uint16_t)((configCPU_CLOCK_HZ + ulWantedBaud * 4UL) / (ulWantedBaud * 8UL) - 1); // for 2x mode, using 16 bit avr-gcc capability.
/* Set the 2x speed mode bit */
*usartReg[usartId].ucsrAPtr = U2X_BIT; /* bits 7:2 are status bits, bit 0 set to 0 disables multi-processor comms mode */
/* Enable the Rx and Tx. Also enable the Rx interrupt. The Tx interrupt will get enabled later. */
*usartReg[usartId].ucsrBPtr = RXCIE_BIT | RXEN_BIT | TXEN_BIT;
/* Set the data bit register to 8n1. */
/* Set to asycrhnoous USART (bits 7:6 set to 0), parity disables (bits 5:4 is 0) 1 stop bit (bit 3 set to 0)
* 8 data bits (UCSZ1, UCSZ0 set to 1)
*/
*usartReg[usartId].ucsrCPtr = UCSZ1_BIT | UCSZ0_BIT; // 011 stored in UCSZ2:1 - bit UCSZ2 is zero in register ucsrB (above instruction)
portEXIT_CRITICAL(); // Enables interrupts after configuration
return usartId;
}
xComPortHandle xSerialPortInitMinimal( eCOMPort ePort, uint32_t ulWantedBaud, uint16_t uxTxQueueLength, uint16_t uxRxQueueLength )
{
uint8_t * dataPtr;
xComPortHandle newComPort;
/* Create the ring-buffers used by the serial communications task. */
if( (dataPtr = (uint8_t *)pvPortMalloc( sizeof(uint8_t) * uxRxQueueLength )))
ringBuffer_InitBuffer( &(newComPort.xRxedChars), dataPtr, uxRxQueueLength);
if( (dataPtr = (uint8_t *)pvPortMalloc( sizeof(uint8_t) * uxTxQueueLength )))
ringBuffer_InitBuffer( &(newComPort.xCharsForTx), dataPtr, uxTxQueueLength);
// create a working buffer for vsnprintf on the heap (so we can use extended RAM, if available).
// create the structures on the heap (so they can be moved later).
if( !(newComPort.serialWorkBuffer = (uint8_t *)pvPortMalloc( sizeof(uint8_t) * uxTxQueueLength )))
newComPort.serialWorkBuffer = NULL;
newComPort.usart = ePort; // containing eCOMPort
newComPort.serialWorkBufferSize = uxTxQueueLength; // size of the working buffer for vsnprintf
newComPort.serialWorkBufferInUse = VACANT; // clear the occupation flag.
portENTER_CRITICAL();
switch (newComPort.usart)
{
case USART0:
/*
* Calculate the baud rate register value from the equation in the data sheet. */
/* As the 16MHz Arduino boards have bad karma for serial port, we're using the 2x clock U2X0 */
// for Arduino at 16MHz; above data sheet calculation is wrong. Need below from <util/setbaud.h>
// This provides correct rounding truncation to get closest to correct speed.
// Normal mode gives 3.7% error, which is too much. Use 2x mode gives 2.1% error.
// Or, use 22.1184 MHz over clock which gives 0.00% error, for all rates.
// ulBaudRateCounter = ((configCPU_CLOCK_HZ + ulWantedBaud * 8UL) / (ulWantedBaud * 16UL) - 1); // for normal mode
// ulBaudRateCounter = (uint16_t)((configCPU_CLOCK_HZ + ulWantedBaud * 4UL) / (ulWantedBaud * 8UL) - 1); // for 2x mode
UBRR0 = (uint16_t)((configCPU_CLOCK_HZ + ulWantedBaud * 4UL) / (ulWantedBaud * 8UL) - 1); // for 2x mode, using 16 bit avr-gcc capability.
/* Set the 2x speed mode bit */
UCSR0A = _BV(U2X0);
/* Enable the Rx and Tx. Also enable the Rx interrupt. The Tx interrupt will get enabled later. */
UCSR0B = ( _BV(RXCIE0) | _BV(RXEN0) | _BV(TXEN0));
/* Set the data bit register to 8n1. */
UCSR0C = ( _BV(UCSZ01) | _BV(UCSZ00) );
break;
case USART1:
#if defined(__AVR_ATmega324P__) || defined(__AVR_ATmega644P__)|| defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega324PA__) || defined(__AVR_ATmega644PA__) ||defined(__AVR_ATmega640__) || defined(__AVR_ATmega1280__) || defined(__AVR_ATmega1281__) || defined(__AVR_ATmega2560__) || defined(__AVR_ATmega2561__)
UBRR1 = (uint16_t)((configCPU_CLOCK_HZ + ulWantedBaud * 4UL) / (ulWantedBaud * 8UL) - 1);
UCSR1A = _BV(U2X1);
UCSR1B = ( _BV(RXCIE1) | _BV(RXEN1) | _BV(TXEN1));
UCSR1C = ( _BV(UCSZ11) | _BV(UCSZ10) );
break;
#endif
case USART2:
case USART3:
default:
break;
}
portEXIT_CRITICAL();
return newComPort;
}
