RM48 HDK - Extra Signals

Hi Rustin,

i have notified our HDK owner.  He will get back to you soon.

Hello Rustin,

The RTCK, SRSTn are not a standard IEEE 1149 JTAG signal. RTCK was created to allow the use of synchronized TAP controllers in ARM core, where the JTAG inputs (TMS and TDI) have to cross an asynchronous boundary into the processor clock domain. RTCK has the effect of controlling the TCK from the emulator box to ensure correct JTAG-like behaviour across that clock domain boundary. RTCK is a must in your design. SRSTn is allowed the CCS or other IDE to reset the processor, this is a must in your design. TRSTn is one of the 5 basic JTAG signals (TMS, TDI, TDO, TCK, TRSTn) defined in IEEE 1149. Q2 is not required.

Regards,

QJ 

QJ,

In a previous post I asked about using the MDL-ADA2 and was told that would be possible (see post here: http://e2e.ti.com/support/microcontrollers/hercules/f/312/p/256459/897368.aspx#897368  )

Sooo the MDL-ADA2 schematic is only showing the 5 basic JTAG signals.  If the other two (RTCK, SRSTn) are a must in our design, how is it exactly that we can use the MDL-ADA2 with the RM48L950?

Thanks,

Rustin

QJ,

Thanks for your input and for clarifying the required signals.  Based upon your input, it seems to me like a 20-pin debug (or some custom connection that adds RTCK and SRSTn) is required.  The post that Rustin refers to above mentions that for basic Cortex-R4 CPU access, the RTCK may not be nescessary.  Would you be able to clarify if RTCK + SRSTn are an absolute requirement for accecss to the Cortex-R4?  If it's not absolutely required, what is the trade-off for not including it?  I just want to make sure that we get Rustin pointed in the best direction for his design as far as the debug connection (Whether we go with a 10-pin, 20-pin, or some other type of connector).

Thanks,
Walter

Hi Walter,

RTCLK is required, but STRST is not required. 

Regards,

QJ

QJ,

We wish to use the ARM 10-pin JTAG connector because of it's small size on our RM48L950 board.  We have the RM48 HDK as a reference design using the ARM 20-pin JTAG connector.  If we were to place an ARM 10-pin JTAG connector on our board, I would assume the connections from the MCU to the emulator would need to be made as I have them shown below. Can you please verify the below connections are correct?

MCU                           ARM 10 Pin             ARM 20 Pin

VCCIO source        ->  Pin 1 (VCC)        ->  Pin 1 (VCC)
TMS pin of MCU     ->  Pin 2 (TMS)        ->  Pin 7 (TMS)
TCK pin of MCU     ->  Pin 4 (TCLK)       ->  Pin 9 (TCLK)
TDO pin of MCU     ->  Pin 6 (TDO)        ->  Pin 13 (TDO)
TDI pin of MCU       ->  Pin 8 (TDI)          ->  Pin 5 (TDI)
RTCK pin of MCU   ->  Pin 7 (RTCK)      ->  Pin 11 (RTCK)
nTRST pin of MCU  ->  ?                       ->  Pin 3 (TRST)
nRST pin of MCU    ->  Pin 10 (RESET)  ->  Pin 15 (SRST)
VSS of MCU          ->  Pins 3,5,9           ->  Pins 4,6,8,10,12,14,16,18,20

If the 10 pin connector were used, is it ok to leave the nTRST pin of the MCU out of the JTAG connector and just pulled high all the time?  Or should the nTRST pin of the MCU be tied to the nRST pin of the MCU?

Thank you in advance for any help you can provide.

Hi David,

nTRST is used by debugger to reset the Embedded ICE logic, the TAP controller, and the boundary scan cells. nRST will not reset the debug logic, and TAP controller. The debugger will also work if nTRST pin is not connected, but you may experience some limitations when debugging. The nTRST and nRST should be separated.

Regards,

QJ

Thanks QJ.

QJ,
Thanks for providing feedback for David.

David,
Do you have enough information to finish your schematic?

Regards,
Walter

Walter,

yes, I believe we have all the information we need.