The following algorithm puts the device in parallel programming mode:
1. Apply power between VCC and GND.
2. Set RESET to “0” and toggle XTAL1 at least six times.
3. Set the Prog_enable pins listed in Table 25-8 on page 340 to “0000” and wait at le
4. Apply 11.5 - 12.5V to RESET. Any activity on Prog_enable pins within 100 ns after
+12V has been applied to RESET, will cause the device to fail entering programm
5. Wait at least 50 µs before sending a new command.