Can I Daisy-chain Multiple E5 or A7 Devices
over JTAG?

With new capabilities in FastChip 2.3.0, it is indeed possible to download and debug an E5 or A7 CSoC device even when it is part of a multi-device JTAG daisy-chain.  FastChip 2.3.0 and later includes the Triscend MutliJTAG Server (TMJS) which allows you to specify the JTAG chain in your application and to select a specific Triscend device on the chain to download or debug.

An example JTAG chain showing three devices. The last two are Triscend CSoC devices. The first is from another vendor. Using TMJS, FastChip Device Link (FDL) and your source-level debugger can communicate directly with a selected device on the chain.

Figure 1.  An example JTAG chain with three devices, connected via TMJS.

Figure 1 shows an example JTAG chain with three devices.  The second and third devices in the chain are Triscend CSoC devices.  The first is from another vendor.  The TMJS server allows a client application, like FastChip Device Link (FDL) or your source-level debugger to communicate directly with the selected Triscend device on the chain.  The TMJS command jselect allows you to select a specific device.  The TMJS jdetect detects and lists the devices on the chain.

To handle any non-Triscend devices on the chain, TMJS requires some additional JTAG information.  TMJS must know the length of the JTAG instruction register (IR) of all devices in the JTAG chain before it can scan the chain correctly.

To specify a non-Triscend device, perform the following steps.

 Create or edit a plain text file called jtaglist.tjd in the following directory.  This directory path assumes that FastChip was installed in the default location.

C:\Triscend\FastChip\bin

 Specify all non-Triscend JTAG devices used in your application in the jtaglist.tjd file.  The description for each non-Triscend device must be on its own line.  Separate the fields with commas.

Each device description has the following format.

JTAG_ID,IR_BITLEN,NAME

The JTAG_ID must match the device’s JTAG identifier code (IDCODE) if it has one.  If it has none or the code is unknown, use 0x0.

The IR_BITLEN value specifies the number of bits in the device’s JTAG instruction register (IR).  This value is critical and must be correct.

The NAME field is a user-defined label and can be from 1 to 31 ASCII characters long.

You do not need to specify values for Triscend devices.  The FastChip software is already well acquainted with these components.

The following example lists two non-Triscend devices.

0x0,5,MyUnknownDevice

0x27790061,4,SHARP_ARM7

 Save the jtaglist.tjd file.

 Launch the TMJS server.

TMJS first attempts to match up unknown devices with the user specified ID codes.  Then, it assigns non-Triscend devices using the devices specified in jtaglist.tjd, starting with the first device in the chain.  The first device is where the TDI JTAG signal enters the chain, which is the device on the left in Figure 1.  The last device is where the TDO JTAG exits the chain, or the right-most device.

 Select the Triscend device on the chain with which you wish to communicate using the TMJS jselect command.  Later, you can communicate with other devices by changing your selection.

 Download and debug to the selected Triscend device just like you would if it were a stand-alone design.

 

FastChip Version: 2.3.0

This solution may or may not apply to other versions of the FastChip development system.

 

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