4.4.4 Connecting to an SPI Target

The recommended pinout for the 6-pin SPI connector is shown in Figure 4-10.

Connection to a 6-pin 100-mil SPI Header

Use the 6-pin 100-mil tap on the flat cable (included in some kits) to connect to a standard 100-mil SPI header.

Connection to a 6-pin 50-mil SPI Header

Use the adapter board (included in some kits) to connect to a standard 50-mil SPI header.

Connection to a Custom 100-mil Header

The 10-pin mini-squid cable should be used to connect between the Atmel-ICE AVR connector port and the target board. Six connections are required, as described in the table below.

Important:

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 or Atmel Studio 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.

Info:

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.

Table 4-11. Atmel-ICE SPI Pin Mapping
Atmel-ICE AVR PORT PinsTarget PinsMini-Squid PinSPI Pinout
Pin 1 (TCK)SCK13
Pin 2 (GND)GND26
Pin 3 (TDO)MISO31
Pin 4 (VTG)VTG42
Pin 5 (TMS)5
Pin 6 (nSRST)/RESET65
Pin 7 (not connected)7
Pin 8 (nTRST)8
Pin 9 (TDI)MOSI94
Pin 10 (GND)0