TMS320C6713BZDP does not work

[Gongyuwei Gonn]

Hello:

I am a beginner for dsp. In past month, I designed a dsp board. Now, I am testing the board.

However, sadly,:sad: my dsp can't work. This may be the smallest thing for long time user, but I can't find the answer. I followed the instruction on the web, and checked my clkout2 and clkout3 outputs. I find that clkout2 sends out a clock signal of unstable frequency before dsp is reset. It seems that dsp is not damaged. After dsp is reset, clkout2 and clkout3 output no signal and remain low level. JTAG interface can not be connected too. CCS tells me that dsp IC returns no response.

Can someone tell me whether my dsp IC is damaged, or my circuit is wrong?
Thank you very much!

Gong yuwei

 

[Gongyuwei Gonn]

hi, I tested my board today, and found what resulted the problem. My reset signal can not reset dsp IC. My reset signal was generated from a button. When I pressed it, reset pin was connected to GND. when it was disconnect, reset pin was pulled up to 3.3V. The reset signal generated by this circuit can not work, but when I use a metal wire to touch the reset pin, to my surprise, my dsp IC are reset and work fine. JTAG can be used too. I measured the reset pin while metal wire touched the pin, and found that it produced a oscillating signal larger than 5V. The signal lasted for almost 50ns, but it can reset dsp IC effectively. Then, I connected reset pin to the output of a signal generator, which produced a 3.3V pulse. I thought it should be a prefect reset signal, but it can not work too, can someone explain this interesting thing to me?

Thank you very much!

Gong yuwei

 

[bigdogguru]

Is the dev board of your design or a commercial design?

Can you post schematics of the dev board?

What specific version of the DSP is on your dev board? There have been several changes made involving the RESET pin and the associated IPU.

Will the dev board reset correctly if the JTAG programmer/debugger is not attached?

Reference: TMS320C6713B Floating-Point Digital Signal Processor (Rev. B) Datasheet: Section: IEEE 1149.1 JTAG compatibility statement, Page: 95

IEEE 1149.1 JTAG compatibility statement

The TMS320C6713B DSP requires that both TRST and RESET resets be asserted upon power up to be
properly initialized. While RESET initializes the DSP core, TRST initializes the DSP’s emulation logic. Both
resets are required for proper operation.

Note: TRST is synchronous and must be clocked by TCLK; otherwise, BSCAN may not respond as expected
after TRST is asserted.

While both TRST and RESET need to be asserted upon power up, only RESET
needs to be released for the DSP to boot properly. TRST may be asserted indefinitely for normal operation,
keeping the JTAG port interface and DSP’s emulation logic in the reset state. TRST only needs to be released
when it is necessary to use a JTAG controller to debug the DSP or exercise the DSP’s boundary scan functionality.

The TMS320C6713B DSP includes an internal pulldown (IPD) on the TRST pin to ensure that TRST will always
be asserted upon power up and the DSP’s internal emulation logic will always be properly initialized when this
pin is not routed out. JTAG controllers from Texas Instruments actively drive TRST high. However, some
third-party JTAG controllers may not drive TRST high but expect the use of an external pullup resistor on TRST.
When using this type of JTAG controller, assert TRST to initialize the DSP after powerup and externally drive
TRST high before attempting any emulation or boundary scan operations.

Following the release of RESET, the low-to-high transition of TRST must be “seen” to latch the state of EMU1
and EMU0. The EMU[1:0] pins configure the device for either Boundary Scan mode or Emulation mode. For
more detailed information, see the terminal functions section of this data sheet.

Note: The DESIGN−WARNING section of the TMS320C6713B BSDL file contains information and constraints
regarding proper device operation while in Boundary Scan Mode.

For more detailed information on the C6713B JTAG emulation, see the TMS320C6000 DSP Designing for JTAG
Emulation Reference Guide(literature number SPRU641).

Reference: TMS320C6713, TMS320C6713B Silicon Errata, Section: RESET Pin Has No Internal Pullup Resistor, Page: 15

RESET Pin Has No Internal Pullup Resistor

On the C6713B silicon revision 2.0, the RESETpin does not have an internal pullup resistor.
When designing a new PCB using C6713B silicon revision 2.0, either incorporate a voltage supervisor that drives
when in the inactive state (RESET = 1) or include an external pullup resistor on the RESETpin.

BigDog

 

[Gongyuwei Gonn]

Hi, dear Bigdogguru, thank you for your suggestions.

The circuit I tested is the dev board of my design. My schematics of the dev board is in my work computer, and I can not copy it to the web now. However, I can take pictures with my cellphone. In a few days, I will replace them with my schematic. I am sorry for the inconvenience.




Above two pictures show the connection of configuration pins.



This is my reset circuit. it does not work.:-(

My dsp IC is TMS320C6713BZDP-225. Datasheet shows that 300M version needs 1.4V core power, my IC needs 1.2V only. I don't know how to determine silicon revision of my IC. The below is the top mark of my dsp ic, can you help me determine silicon revision?

TMS320C6713BZDP
C20-25P01R8
0675456 E1

I tested my board again. when the JTAG programmer/debugger is not attached, reset circuit did not work too. I guess that the problem may not be resulted form jtag reset signal.

My reset circuit can not work when board powers on. The output of clkout2 is unstable after power on and before reset.



the yellow one is the signal on reset pin, and green one is the output of clkout2.



the output of clkout2 is unstable.



After reset clkout2 remains low level. PLL of DSP may not work, so the whole IC has no clock internally. I think that befor reset the dsp IC is in uncertainty. Therefore output of PLL is unstable.

In the test, I found that touching nearby ground also can reset the IC effectively.



the yellow one shows the signal on reset pin when I touch nearby ground, and green one is the output of clkout2. Before touching PLL has no output, and after that PLL works. Therefore, dsp IC works.



This is the enlargement of signal actions when I touch nearby ground.



the yellow one shows the signal on reset pin when I touch reset pin, and green one is the output of clkout2. The reset signal resulted is good, and PLL works.



In above picture, I touched the reset pin. The reset signal resulted was very bad, but it could reset dsp IC too. Then PLL worked, and the whole dsp IC worked.

It is said that reset signal generated from button always has some glitches, but In above pictures reset signal resulted from touching has glitches too. however it works. can you tell me which conditions the reset signal needs to meet? or when I touched the reset pin some conditions were meet?

Thank you very much.
Sincerely

Gong yuwei