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Speed up bit-banged USART code in the AVRISP project.

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Fix project text files to refer to "project" instead of "demo".
This commit is contained in:
Dean Camera 2009-12-15 11:12:38 +00:00
parent 2f6c096050
commit 4f74075fad
9 changed files with 59 additions and 55 deletions
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1
Projects/AVRISP/Lib/NVMTarget.c
View file

@ -182,7 +182,6 @@ bool NVMTarget_ReadMemory(uint32_t ReadAddress, uint8_t* ReadBuffer, uint16_t Re
* \param[in] WriteCommand Command to send to the device to write each memory byte
* \param[in] WriteAddress Start address to write to within the target's address space
* \param[in] WriteBuffer Buffer to source data from
* \param[in] WriteSize Number of bytes to write
*
* \return Boolean true if the command sequence complete successfully
*/

41
Projects/AVRISP/Lib/PDITarget.c
View file

@ -45,9 +45,8 @@ volatile bool IsSending;
/** Software USART raw frame bits for transmission/reception. */
volatile uint16_t SoftUSART_Data;
/** Bits remaining to be sent or received via the software USART. */
volatile uint8_t SoftUSART_BitCount;
/** Bits remaining to be sent or received via the software USART - set as a GPIOR for speed. */
#define SoftUSART_BitCount GPIOR2
/** ISR to manage the software USART when bit-banged USART mode is selected. */
ISR(TIMER1_COMPA_vect, ISR_BLOCK)
@ -59,21 +58,13 @@ ISR(TIMER1_COMPA_vect, ISR_BLOCK)
if (!(SoftUSART_BitCount))
return;
/* Check to see if the current clock state is on the rising or falling edge */
bool IsRisingEdge = (BITBANG_PDICLOCK_PORT & BITBANG_PDICLOCK_MASK);
if (IsSending && !IsRisingEdge)
{
if (SoftUSART_Data & 0x01)
BITBANG_PDIDATA_PORT |= BITBANG_PDIDATA_MASK;
else
BITBANG_PDIDATA_PORT &= ~BITBANG_PDIDATA_MASK;
SoftUSART_Data >>= 1;
SoftUSART_BitCount--;
}
else if (!IsSending && IsRisingEdge)
/* Check to see if we are at a rising or falling edge of the clock */
if (BITBANG_PDICLOCK_PORT & BITBANG_PDICLOCK_MASK)
{
/* If at rising clock edge and we are in send mode, abort */
if (IsSending)
return;
/* Wait for the start bit when receiving */
if ((SoftUSART_BitCount == BITS_IN_FRAME) && (BITBANG_PDIDATA_PIN & BITBANG_PDIDATA_MASK))
return;
@ -84,6 +75,20 @@ ISR(TIMER1_COMPA_vect, ISR_BLOCK)
SoftUSART_Data >>= 1;
SoftUSART_BitCount--;
}
else
{
/* If at falling clock edge and we are in receive mode, abort */
if (!IsSending)
return;
if (SoftUSART_Data & 0x01)
BITBANG_PDIDATA_PORT |= BITBANG_PDIDATA_MASK;
else
BITBANG_PDIDATA_PORT &= ~BITBANG_PDIDATA_MASK;
SoftUSART_Data >>= 1;
SoftUSART_BitCount--;
}
}
#endif
@ -120,7 +125,7 @@ void PDITarget_EnableTargetPDI(void)
asm volatile ("NOP"::);
/* Fire timer compare ISR every 100 cycles to manage the software USART */
OCR1A = 100;
OCR1A = 80;
TCCR1B = (1 << WGM12) | (1 << CS10);
TIMSK1 = (1 << OCIE1A);