CCS/TMS320F280049: A question about 0049 Crystal oscillator

Hello,
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Regards
Himanshu

HI, We read more register, please see as below:

Hi Erwin,

Based from the register configurations you have sent above, looks like clock is sourced from INTOSC2 (internal oscillator 2) [CLKSRCCTRL1.OSCCLKSRCSEL = 0]. This clock provides 10MHz to the PLL so if customer is shorting the clock input to F280049, device still has a clock, hence not reporting MCDOFF.

Regards,
Joseph

hi, Joseph

sorry to reply you late, we double checked with my customer, here is customer's timer configuration:

TIMER0 use an external oscillator for 20us interrupt;

TIMER2 use an internal oscillator for 1ms interrupt;

here is the code:

configCPUTimer(CPUTIMER0_BASE, DEVICE_SYSCLK_FREQ, 20);   

configCPUTimer(CPUTIMER2_BASE, INT1_OSC_CLK, 1000);     

after oscillator disconnected with Ground, we found PWM1 was high for a long time, it's dangerous for our application.

this is the waveform:

Green: XRSN reset signal

Blue: External oscillator output

Red: PWM1

if we do the test with debuger, when we short the oscillator to groud, we found the pointer stop at this address of BOOTROM, 

RPC  0X3FC807

PC   0X3FB02A

Our question is,

why PWM1 will output high level? 

why program stop at this address?

Thank you

Erwin,

Let's put aside the PWM issue for now. I have a few questions:

1. Why do you have a capacitor on the output of the oscillator. What is the value of this capacitor?

2. In my experience, when registers are reading back 0xBAD, it means some power issue is going on. Have you monitored the VDDA/VDDIO and VDD power rails to make sure nothing strange is going on with them? You should also monitor XRSn.

3. What oscillator are you using? Can you provide a zoomed in scope shot (a few cycles) of the oscillation?

hi, Frank,

Please see my input:

1. Why do you have a capacitor on the output of the oscillator. What is the value of this capacitor?

the frequency is 20MHz, we connect C151 to ground, it's 27pF

2. In my experience, when registers are reading back 0xBAD, it means some power issue is going on. Have you monitored the VDDA/VDDIO and VDD power rails to make sure nothing strange is going on with them? You should also monitor XRSn.

Please see the waveform below, we didn't see any abnormal phenomena

CH1: XRSN

CH2: VDDIO C11

CH3:VDDA C151

CH4: 20MHz_CLK output

What oscillator are you using? Can you provide a zoomed in scope shot (a few cycles) of the oscillation

CH1: XRSN

CH2: VDDIO C11

CH3:VDDA C151

CH4: 20MHz_CLK output

3. What oscillator are you using? Can you provide a zoomed in scope shot (a few cycles) of the oscillation

Erwin,

Thanks for providing the extra details. Your oscillator output looks ok. It does have a fair amount of overshoot and undershoot so you might want to look into terminating it properly.

The more concerning part of the new information you provided is that i see XRSn dipping low a few times. This means the device is getting reset at least 3 times. Is this intentional? Is XRSn being driven externally by something else? I have circled the areas I'm referring to in your capture.

hi,Frank,

 XRSn is driven internally.

Thank you