diff options
Diffstat (limited to 'Projects/AVRISP/Lib/PDITarget.c')
| -rw-r--r-- | Projects/AVRISP/Lib/PDITarget.c | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/Projects/AVRISP/Lib/PDITarget.c b/Projects/AVRISP/Lib/PDITarget.c index 28df55021..1bbb4d577 100644 --- a/Projects/AVRISP/Lib/PDITarget.c +++ b/Projects/AVRISP/Lib/PDITarget.c @@ -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);
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