diff options
Diffstat (limited to 'Projects/AVRISP-MKII/Lib/ISP/ISPTarget.c')
| -rw-r--r-- | Projects/AVRISP-MKII/Lib/ISP/ISPTarget.c | 49 |
1 files changed, 44 insertions, 5 deletions
diff --git a/Projects/AVRISP-MKII/Lib/ISP/ISPTarget.c b/Projects/AVRISP-MKII/Lib/ISP/ISPTarget.c index e596cfe28..fe2f50d07 100644 --- a/Projects/AVRISP-MKII/Lib/ISP/ISPTarget.c +++ b/Projects/AVRISP-MKII/Lib/ISP/ISPTarget.c @@ -119,7 +119,7 @@ ISR(TIMER1_COMPA_vect, ISR_BLOCK) { if (!(PINB & (1 << 1))) { - if (SoftSPI_Data & 0x80) + if (SoftSPI_Data & (1 << 7)) PORTB |= (1 << 2); else PORTB &= ~(1 << 2); @@ -132,10 +132,11 @@ ISR(TIMER1_COMPA_vect, ISR_BLOCK) TCCR1B = 0; if (PINB & (1 << 3)) - SoftSPI_Data |= 0x01; + SoftSPI_Data |= (1 << 0); } - PORTB ^= (1 << 1); + /* Fast toggle of PORTB.1 via the PIN register (see datasheet) */ + PINB |= (1 << 1); } /** Initialises the appropriate SPI driver (hardware or software, depending on the selected ISP speed) ready for @@ -159,8 +160,7 @@ void ISPTarget_Init(void) DDRB |= ((1 << 1) | (1 << 2)); PORTB |= ((1 << 0) | (1 << 3)); - TIMSK1 = (1 << OCIE1A); - OCR1A = pgm_read_word(&TimerCompareFromSCKDuration[SCKDuration - sizeof(SPIMaskFromSCKDuration)]); + ISPTarget_ConfigureSoftwareISP(SCKDuration); } } @@ -177,9 +177,48 @@ void ISPTarget_ShutDown(void) { DDRB &= ~((1 << 1) | (1 << 2)); PORTB &= ~((1 << 0) | (1 << 3)); + + ISPTarget_ConfigureRescueClock(); } } +/** Configures the AVR to produce a .5MHz rescue clock out of the OCR1A pin of the AVR, so + * that it can be fed into the XTAL1 pin of an AVR whose fuses have been misconfigured for + * an external clock rather than a crystal. When used, the ISP speed must be 125KHz for this + * functionality to work correctly. + */ +void ISPTarget_ConfigureRescueClock(void) +{ + /* Configure OCR1A as an output for the specified AVR model */ + #if defined(USB_SERIES_2_AVR) + DDRC |= (1 << 6); + #else + DDRB |= (1 << 5); + #endif + + /* Start Timer 1 to generate a .5MHz clock on the OCR1A pin */ + TIMSK1 = 0; + TCNT1 = 0; + OCR1A = (F_CPU / 2 / 500000UL); + TCCR1A = (1 << COM1A0); + TCCR1B = ((1 << WGM12) | (1 << CS10)); +} + +/** Configures the AVR's timer ready to produce software ISP for the slower ISP speeds that + * cannot be obtained when using the AVR's hardware SPI module. + * + * \param[in] SCKDuration Duration of the desired software ISP SCK clock + */ +void ISPTarget_ConfigureSoftwareISP(const uint8_t SCKDuration) +{ + /* Configure Timer 1 for software ISP using the specified SCK duration */ + TIMSK1 = (1 << OCIE1A); + TCNT1 = 0; + OCR1A = pgm_read_word(&TimerCompareFromSCKDuration[SCKDuration - sizeof(SPIMaskFromSCKDuration)]); + TCCR1A = 0; + TCCR1B = 0; +} + /** Sends and receives a single byte of data to and from the attached target via software SPI. * * \param[in] Byte Byte of data to send to the attached target |