UCD90160 JTAG Programming

Hi Tom,

 From the Configuration Programming of UCD Devices.pdf, seems only one JTAG device for programming: 

• The UCD device can be set to PMBus address 126 to leave JTAG always enabled. Note – using this method will disable use of the JTAG pins as GPIO in devices that support multiplexing of these pins. You must also ensure that no other device on the same PMBus could end up at address 126. For example, do not use this method when there are multiple UCD devices on the same PMBus.

Specifically looking to determine if we can put a UCD90160 at one address and a different device at a different address on the same JTAG chain, or must they be on different JTAG chains?

From JTAG point of view, multiple devices can be on the same chain. The BSDL file can be downloaded from product page on ti.com. Note that the JTAG port in UCD90160 does not support boundary scan.

However, JTAG is only enabled when PMBus address is 126d. So you cannot have JTAG enabled while having a different address. With one exception: JTAG is enabled when the device is blank (no configuration).

When the device is on the board, you can use PMBus (I2C) port for programming. It is a preferred method, because you will want to use Fusion GUI for debugging. Fusion GUI uses PMBus command set.  So you will have I2C anyway.

So the question comes down to this - if I have a new, blank UCD90160 on the newly assembled pcb, and I also have other JTAG unique address devices on the same pcb, and I start a communication with one of those other JTAG devices, will the UCD90160 'see' this communication and act as if it is being addressed?  If that is the case, then it would seem the very FIRST thing I must do when power-ON the pcb for the first time is to program the UCD90160, correct? 

Alternatively, pre-program the UCD90160 before assembly onto the pcb.  Although, one advantage of the JTAG with In-Circuit Test is to be able to program such devices immediately after the assembly process.

Please provide a procedure for programming a newly built pcb with other JTAG devices.

~Leonard 

Yes, reviewed that, and it is more for a functional test; we're looking for JTAG programming from an ICT at production verification and test. 

Also, that document does not seem to be available on the TI website.  I downloaded it from an E2E post, it does not have a document number, and I prefer to point the end-user to a weblink to get the document.