TMS570LC4357: nRST pin held low

Priya Kakarla Naga Lakshmi

Part Number: TMS570LC4357

We are unable to flash the TMS570LC4357 processor through JTAG. This is the first time this particular DSP is being flashed.

We have ensured the CLK and nPORRST pins have valid signals, i.e. CLK is switching fine and nPORRST is high. However, we notice nRST pin is held low and we believe this is the reason why we have been unsuccessful in flashing. An external pull up through 1K resistor has been provided at nRST pin and it looks like the DSP is driving the nRST pin low internally.

Is there any way to fix this?

over 5 years ago

0 Miro over 5 years ago

TI__Mastermind 21425 points

Hello,

The reasons for nRST being low are listed in Datasheet, table 6-5 Causes of warm reset.

What error are you receiving when trying to connect to MCU?

0 Miro over 5 years ago in reply to Miro

TI__Mastermind 21425 points

Hello,

If you already had success with downloading the firmware before the problem occurs, take a look at this thread:

e2e.ti.com/.../465986

0 Priya Kakarla Naga Lakshmi over 5 years ago in reply to Miro

Prodigy 130 points

The error code that we are getting when we try to flash is 2131. We also tried to connect to IcePick and it still gave the same error. Attached is the snapshot of error.

We looked into the datasheet table that you referred. We have ruled out some things by making some hardware measurements. Details are as follows.

1. Power-Up Reset: Voltage at nPORRST pin is 3.2073V. So this cannot be causing reset.

2. Oscillator fail: Oscillator Clock is 16MHz with good signal integrity. So this cannot be causing reset.

3. PLL slip: Since external oscillator is ok, we assumed PLL should be good? Not likely cause for reset.

4. Watchdog exception: We have disabled external watchdog and our understanding is internal watchdog is disabled by default. Since we have not successfully flashed the device even once, this should not be causing reset.

5. Debugger Reset : How do we check this is not causing reset?

6. CPU Reset: How do we check this is not causing reset?

7. Software Reset: This should be caused by application software and there is no code flashed into the processor yet. So not likely cause for reset.

8. External Reset: nRST has been pulled externally high. So this is not causing reset.

Is there a way to read the system status flag or any other method to know what is causing reset?