I am looking at using the telnet commands to do some low level JTAG commands using OpenOCD
here’s what I’m looking at the momement
endstate rti
irscan 0 0x5 #Set to EXTEST on my device
var data 16 #create a space for data
field data 0 0xBEEF #Define data’s value
drscan 0 data #???
var data #display value of data
Does this implementation of drscan push data onto the JTAG chain like this:
0xBEEF->[0x0001]->Data Out
^data ^Boundry Scan Registers
Shift right 1 time…
0x5F77->[0x8000] → 1 (data pushed out is 1)
Repeat this process 16 times (so our new word is the boundry scan register)
Now this may have been confusing, but at the root of what I’m looking for is how the drscan command works.