How many connections are required for JTAG
From MKRD.info Wiki
The JTAG interface standard requires the following connections:
- TDI (Test Data In)
- TDO (Test Data Out)
- TCK (Test Clock)
- TMS (Test Mode Select)
However, when designing your hobby project with a JTAG interface, allocate at least 8 pins on a header (dedicated header is best), for the following signals:
- TDI
- TDO
- TCK
- TMS
- TRST (Test Reset)
- VDD
- GND
- DONE
Plus any chip-specific or platform-specific configuration pins. For example, most devices and programmers use the DONE signal to specify that the programming succeeded.