3.3.4.2.1 Connecting to an AVR SPI Target
The MPLAB PICkit 5 provides a direct connection for new designs (DGI SPI) or a legacy 10-pin 50-mil JTAG connection for the 6-pin SPI interface using the adapter board.
The SPI interface is effectively disabled when the debugWIRE Enable (DWEN) fuse is programmed, even if the SPIEN fuse is also programmed. To re-enable the SPI interface, the ‘disable debugWIRE’ command must be issued while in a debugWIRE debugging session. Disabling debugWIRE in this manner requires that the SPIEN fuse is already programmed. If MPLAB X IDE fails to disable debugWIRE, it is probably because the SPIEN fuse is NOT programmed. If this is the case, it is necessary to use a High-Voltage Programming interface to program the SPIEN fuse.
The SPI interface is often referred to as “ISP” since it was the first in-system programming interface on Microchip AVR products. Other interfaces are now available for in-system programming.