+ * \hideinitializer
+ */
+static const uint16_t TimerCompareFromSCKDuration[] PROGMEM =
+{
+ ISP_TIMER_COMP(96386), ISP_TIMER_COMP(89888), ISP_TIMER_COMP(84211), ISP_TIMER_COMP(79208), ISP_TIMER_COMP(74767),
+ ISP_TIMER_COMP(70797), ISP_TIMER_COMP(67227), ISP_TIMER_COMP(64000), ISP_TIMER_COMP(61069), ISP_TIMER_COMP(58395),
+ ISP_TIMER_COMP(55945), ISP_TIMER_COMP(51613), ISP_TIMER_COMP(49690), ISP_TIMER_COMP(47905), ISP_TIMER_COMP(46243),
+ ISP_TIMER_COMP(43244), ISP_TIMER_COMP(41885), ISP_TIMER_COMP(39409), ISP_TIMER_COMP(38278), ISP_TIMER_COMP(36200),
+ ISP_TIMER_COMP(34335), ISP_TIMER_COMP(32654), ISP_TIMER_COMP(31129), ISP_TIMER_COMP(29740), ISP_TIMER_COMP(28470),
+ ISP_TIMER_COMP(27304), ISP_TIMER_COMP(25724), ISP_TIMER_COMP(24768), ISP_TIMER_COMP(23461), ISP_TIMER_COMP(22285),
+ ISP_TIMER_COMP(21221), ISP_TIMER_COMP(20254), ISP_TIMER_COMP(19371), ISP_TIMER_COMP(18562), ISP_TIMER_COMP(17583),
+ ISP_TIMER_COMP(16914), ISP_TIMER_COMP(16097), ISP_TIMER_COMP(15356), ISP_TIMER_COMP(14520), ISP_TIMER_COMP(13914),
+ ISP_TIMER_COMP(13224), ISP_TIMER_COMP(12599), ISP_TIMER_COMP(12031), ISP_TIMER_COMP(11511), ISP_TIMER_COMP(10944),
+ ISP_TIMER_COMP(10431), ISP_TIMER_COMP(9963), ISP_TIMER_COMP(9468), ISP_TIMER_COMP(9081), ISP_TIMER_COMP(8612),
+ ISP_TIMER_COMP(8239), ISP_TIMER_COMP(7851), ISP_TIMER_COMP(7498), ISP_TIMER_COMP(7137), ISP_TIMER_COMP(6809),
+ ISP_TIMER_COMP(6478), ISP_TIMER_COMP(6178), ISP_TIMER_COMP(5879), ISP_TIMER_COMP(5607), ISP_TIMER_COMP(5359),
+ ISP_TIMER_COMP(5093), ISP_TIMER_COMP(4870), ISP_TIMER_COMP(4633), ISP_TIMER_COMP(4418), ISP_TIMER_COMP(4209),
+ ISP_TIMER_COMP(4019), ISP_TIMER_COMP(3823), ISP_TIMER_COMP(3645), ISP_TIMER_COMP(3474), ISP_TIMER_COMP(3310),
+ ISP_TIMER_COMP(3161), ISP_TIMER_COMP(3011), ISP_TIMER_COMP(2869), ISP_TIMER_COMP(2734), ISP_TIMER_COMP(2611),
+ ISP_TIMER_COMP(2484), ISP_TIMER_COMP(2369), ISP_TIMER_COMP(2257), ISP_TIMER_COMP(2152), ISP_TIMER_COMP(2052),
+ ISP_TIMER_COMP(1956), ISP_TIMER_COMP(1866), ISP_TIMER_COMP(1779), ISP_TIMER_COMP(1695), ISP_TIMER_COMP(1615),
+ ISP_TIMER_COMP(1539), ISP_TIMER_COMP(1468), ISP_TIMER_COMP(1398), ISP_TIMER_COMP(1333), ISP_TIMER_COMP(1271),
+ ISP_TIMER_COMP(1212), ISP_TIMER_COMP(1155), ISP_TIMER_COMP(1101), ISP_TIMER_COMP(1049), ISP_TIMER_COMP(1000),
+ ISP_TIMER_COMP(953), ISP_TIMER_COMP(909), ISP_TIMER_COMP(866), ISP_TIMER_COMP(826), ISP_TIMER_COMP(787),
+ ISP_TIMER_COMP(750), ISP_TIMER_COMP(715), ISP_TIMER_COMP(682), ISP_TIMER_COMP(650), ISP_TIMER_COMP(619),
+ ISP_TIMER_COMP(590), ISP_TIMER_COMP(563), ISP_TIMER_COMP(536), ISP_TIMER_COMP(511), ISP_TIMER_COMP(487),
+ ISP_TIMER_COMP(465), ISP_TIMER_COMP(443), ISP_TIMER_COMP(422), ISP_TIMER_COMP(402), ISP_TIMER_COMP(384),
+ ISP_TIMER_COMP(366), ISP_TIMER_COMP(349), ISP_TIMER_COMP(332), ISP_TIMER_COMP(317), ISP_TIMER_COMP(302),
+ ISP_TIMER_COMP(288), ISP_TIMER_COMP(274), ISP_TIMER_COMP(261), ISP_TIMER_COMP(249), ISP_TIMER_COMP(238),
+ ISP_TIMER_COMP(226), ISP_TIMER_COMP(216), ISP_TIMER_COMP(206), ISP_TIMER_COMP(196), ISP_TIMER_COMP(187),
+ ISP_TIMER_COMP(178), ISP_TIMER_COMP(170), ISP_TIMER_COMP(162), ISP_TIMER_COMP(154), ISP_TIMER_COMP(147),
+ ISP_TIMER_COMP(140), ISP_TIMER_COMP(134), ISP_TIMER_COMP(128), ISP_TIMER_COMP(122), ISP_TIMER_COMP(116),
+ ISP_TIMER_COMP(111), ISP_TIMER_COMP(105), ISP_TIMER_COMP(100), ISP_TIMER_COMP(95.4), ISP_TIMER_COMP(90.9),
+ ISP_TIMER_COMP(86.6), ISP_TIMER_COMP(82.6), ISP_TIMER_COMP(78.7), ISP_TIMER_COMP(75.0), ISP_TIMER_COMP(71.5),
+ ISP_TIMER_COMP(68.2), ISP_TIMER_COMP(65.0), ISP_TIMER_COMP(61.9), ISP_TIMER_COMP(59.0), ISP_TIMER_COMP(56.3),
+ ISP_TIMER_COMP(53.6), ISP_TIMER_COMP(51.1)
+};
+
+/** Currently selected SPI driver, either hardware (for fast ISP speeds) or software (for slower ISP speeds). */
+bool ISPTarget_HardwareSPIMode = true;
+
+/** Software SPI data register for sending and receiving */
+static volatile uint8_t ISPTarget_SoftSPI_Data;
+
+/** Number of bits left to transfer in the software SPI driver */
+static volatile uint8_t ISPTarget_SoftSPI_BitsRemaining;
+
+
+/** ISR to handle software SPI transmission and reception */
+ISR(TIMER1_COMPA_vect, ISR_BLOCK)
+{
+ /* Check if rising edge (output next bit) or falling edge (read in next bit) */
+ if (!(PINB & (1 << 1)))
+ {
+ if (ISPTarget_SoftSPI_Data & (1 << 7))
+ PORTB |= (1 << 2);
+ else
+ PORTB &= ~(1 << 2);
+ }
+ else
+ {
+ ISPTarget_SoftSPI_Data <<= 1;
+
+ if (!(--ISPTarget_SoftSPI_BitsRemaining))
+ {
+ TCCR1B = 0;
+ TIFR1 = (1 << OCF1A);
+ }
+
+ if (PINB & (1 << 3))
+ ISPTarget_SoftSPI_Data |= (1 << 0);
+ }
+
+ /* Fast toggle of PORTB.1 via the PIN register (see datasheet) */
+ PINB |= (1 << 1);
+}
+
+/** Initializes the appropriate SPI driver (hardware or software, depending on the selected ISP speed) ready for
+ * communication with the attached target.