@ -70,8 +70,10 @@ ISR(TIMER1_COMPA_vect, ISR_BLOCK)
if ( ( SoftUSART_BitCount = = BITS_IN_FRAME ) & & ( BITBANG_PDIDATA_PIN & BITBANG_PDIDATA_MASK ) )
return ;
/* Shift in the bit one less than the frame size in position, so that the start bit will eventually
* be discarded leaving the data to be byte - aligned for quick access */
if ( BITBANG_PDIDATA_PIN & BITBANG_PDIDATA_MASK )
SoftUSART_Data | = ( 1 < < BITS_IN_FRAME ) ;
SoftUSART_Data | = ( 1 < < ( BITS_IN_FRAME - 1 ) ) ;
SoftUSART_Data > > = 1 ;
SoftUSART_BitCount - - ;
@ -82,6 +84,7 @@ ISR(TIMER1_COMPA_vect, ISR_BLOCK)
if ( ! IsSending )
return ;
/* Set the data line to the next bit value */
if ( SoftUSART_Data & 0x01 )
BITBANG_PDIDATA_PORT | = BITBANG_PDIDATA_MASK ;
else
@ -196,17 +199,20 @@ void PDITarget_SendByte(uint8_t Byte)
bool EvenParityBit = false ;
uint8_t ParityData = Byte ;
/* Compute Even parity bit */
for ( uint8_t i = 0 ; i < 8 ; i + + )
/* Compute Even parity - while a bit is still set, chop off lowest bit and toggle parity bit */
while ( ParityData )
{
EvenParityBit ^ = ParityData & 0x01 ;
ParityData >> = 1 ;
EvenParityBit ^ = true ;
ParityData &= ( ParityData - 1 ) ;
}
/* Calculate the new USART frame data here while while we wait for a previous byte (if any) to finish sending */
uint16_t NewUSARTData = ( ( 1 < < 11 ) | ( 1 < < 10 ) | ( ( uint16_t ) EvenParityBit < < 9 ) | ( ( uint16_t ) Byte < < 1 ) | ( 0 < < 0 ) ) ;
while ( SoftUSART_BitCount ) ;
/* Data shifted out LSB first, START DATA PARITY STOP STOP */
SoftUSART_Data = ( ( uint16_t ) EvenParityBit < < 9 ) | ( ( uint16_t ) Byte < < 1 ) | ( 1 < < 10 ) | ( 1 < < 11 ) ;
SoftUSART_Data = NewUSARTData ;
SoftUSART_BitCount = BITS_IN_FRAME ;
# endif
}
@ -253,7 +259,7 @@ uint8_t PDITarget_ReceiveByte(void)
while ( SoftUSART_BitCount ) ;
/* Throw away the start, parity and stop bits to leave only the data */
return ( uint8_t ) ( SoftUSART_Data > > 1 ) ;
return ( uint8_t ) SoftUSART_Data ;
# endif
}
Dean Camera
15 years ago