AM2432: Changing the boot offset will cause the device to not boot.

Hi Oyama-San,

Are you using a TI EVM or a custom board?

Are you facing this issue only on this particular flash offset (0x80000)? 

Best Regards,

Meet.

Hi Meet,

This issue is on a custom board,.

it is also  occurred on flash offset 0x100000, 0x300000.

Best regard,

Oyama

Hi,

On my board, MCU_PORz output from TPS386000RGPR, same as AM243LP.

However, the capacitor connected to CT1 is 2200pF instead of 2400pF.

When I removed this capacitor and set the PORz output timing to 20ms,

I confirmed that I was able to boot from 0x80000.

Why is pRespPrm-->flags=0 because the output timing of PORz is slightly earlier?

How should I determine the accurate PORz output timing?

Best regard,

Oyama

Hi Oyama-San,

Tomoya Oyama said:

How should I determine the accurate PORz output timing?

I am assigning this thread to a concerned expert for this query, please wait for their response.

Best Regards,

Meet.

Hello Oyama

Thank you.

I am not sure i understand the query.

A delay of 9.5 ms min is required after the ramp of all SOC supplies for the clock to stabilize before the MCU_PORz is pulled high.

Regards,

Sreenivasa

Hi Sreenivasa,

On my board, the MCU_PORZ delay timing is set to 9.6ms.

This meets the requirements, so why does it affect the software behavior?

Best regard,

Oyama

Hello Oyama. 

Thank you.

Please share the MCU_PORz waveform with respect to the supply ramps and MCU_PORz waveform showing the slew.

I will need you to share a schematic in searchable PDF.

Regards,

Sreenivasa

Hello Oyama. 

In the Launchpad, the output of the supervisor connect to an ANDing logic and the AND gate output is connects to the MCU_PORz input.

In the custom board case, the open drain output of the supervisor seems to have been connected to the MCU_PORz input and likely have slew.

This is a reset input with hysteresis. A slow ramp input is likely to glitch the the internal reset.

The MCU_PORz slew should be as min as possible 10..100 nS.

Can you please try adjusting the pullup 10K to a lower value to reduce the slew.

Regards,

Sreenivasa

Hi Sreenivasa,

The slew rate of MCU_PORz was about 1000ns.
At once, I changed the pull-up resistor to 1K and was able to confirm that it was booting from an offset of 0x80000.
However, this still does not meet your recommendation of less than 100ns, so I will consider modifying the circuit.

Are there any other points that could be an issue?

 10k pull-up resistor 

 1k pull-up resistor 

Best regard,

Oyama

Hello Oyama,

Good to hear you were able to resolve the issues related to the boot with change in resistor value.

The rise time measured is from 10..90%.

With the current configuration i do not see any other option to improve other than forcing more current to supervisor and testing. 

In case you are doing any design changes, the recommendation is to add a discrete buffer and a 22 pF glitch filter.

Regards,

Sreenivasa

Hi Sreenivasa,

Kallikuppa Sreenivasa said:

A slow ramp input is likely to glitch the the internal reset.

The MCU_PORz slew should be as min as possible 10..100 nS.

I checked the data sheet and it said the slew rate was 0.0018V/ns (1000ns).

Therefore, I'm thinking of just modifying the PORz output timing,

but do I also need to take measures to shorten the slew rate as much as possible?

If you don't mind, could you please explain again why the slew rate must be 10 ~ 100 ns?

Kallikuppa Sreenivasa said:

the recommendation is to add a discrete buffer and a 22 pF glitch filter.

Where should I put this 22pF glitch filter?

Best regard,

Oyama

Hi Sreenivasa,

I am in the same team as Mr. Oyama, I'm in charge of the hardware.

I have a question about the slew rate of MCU_PORz.

It shows that input slew rate is 1,000ns (Max) at AM2432's datasheet. But you recommend that the MCU_PORz slew should be as min as possible 10..100 nS. Why do you recommend the 10 to 100ns slew?
We improved slew (rise time) to around 100ns by changing pull-up resistor from 10kΩ to 1kΩ. Why do we need to make further improvement of slew (rise time)?

Best regard,

Shigeki Sato

Hello Shigeki Sato

Thank you.

Please refer below FAQ

(+) [FAQ] AM625 / AM623 / AM620-Q1 / AM625-Q1 / AM625SIP: MCU_PORz input slew rate - Processors forum - Processors - TI E2E support forums

Regards,

Sreenivasa

Hello Sreenivasa,

Is the 22pF glitch filter required on the input of MCU_PORz? The AM243x LAUNCH PAD_PROC109E3_SCH I'm referencing doesn't have a capacitor.

Best regard,

Shigeki Sato