JTAG Chain Issues

[shenanigans]

I have a JTAG chain with 3 physical components (STM32F103RE) that each have 2 JTAG TAP Controllers within them. I would like to connect to the JTAG interface connector using the ISP port on my 48Pro2C programmer but I’m having issues.

Test Setup:


Now each device has 2 TAP controllers; the boundary scan controller (IR=5) and the Cortex M3 controller (IR=4)

Device Operation Options (Dataman):
In an attempt to read the 1st device’s ‘option bytes’ I set up the JTAG settings as follows:
Number of devices before target: 1
Number of devices after target: 4
Sum of IR registers lengths of the device before target: 5
Sum of IR registers lengths of the devices after target: 18

After setting the programmer to only read the option bytes and clicking the read button, I get the following error.
Error Message: “Interface Error: link initialization problem!”
(I have tried many other combinations of number of devices and IR register lengths but have always received the same error.

I’m fairly confident in my test setup since I have another device that can scan the JTAG chain and report what is on it. Using the same 20 pin connector used with the Dataman, I can use that tool to successfully read the Device ID from each of the 6 reported devices (6 because each device has two TAP controllers).

So the question is, what am I doing wrong?

[shenanigans]

OK, I've solved the problem and it was a mix between user error (of course) and understanding how the specify the JTAG settings inside of the Dataman software.

User Error:
Not shown in the above diagram was the TRST and RST signals that the Dataman software says should be connected. I had them connected and it would read from the first device but none of the others. Turns out, it will read from all of the devices if you do not connect them and actually only connect what I had shown above.

JTAG Chain Settings:
This is where it gets weird because sometimes you count the JTAG TAP controller and sometimes you don't. It's easier to just show my settings rather than try and explain it.

Device 1:
Number of devices before target: 0
Number of devices after target: 4
Sum of IR registers lengths of the device before target: 0
Sum of IR registers lengths of the devices after target: 18

Device 2:
Number of devices before target: 2
Number of devices after target: 2
Sum of IR registers lengths of the device before target: 9
Sum of IR registers lengths of the devices after target: 9

Device 3:
Number of devices before target: 4
Number of devices after target: 0
Sum of IR registers lengths of the device before target: 18
Sum of IR registers lengths of the devices after target: 0

Thanks to Neil Parker and his engineers for help with this issue.