UCD3138: Questions about the back door in UCD3138 full-bridge hard-switch firmware

zoujiangyilang

Part Number: UCD3138

Hello, I was recently learning the UCD3138 full-bridge hard-switch firmware.
I encountered a problem in the main() function,

If(GioRegs.FAULTIN.bit.FLT3_IN == 0)// Re-Check pin assignment (ADC_EXT/SYNC may be?)
{
// clear_integrity_word();
}

Excuse me, after removing the shield symbol "//" before clear_integrity_word();, does the code play the role of a backdoor？

that is, FLT3_IN is usually set to high. When Flash is locked, FLT3_IN is pulled low. You can unlock it, right?

But the firmware will be shielded by clear_integrity_word(); Why is this? Isn't there no backdoor?

Also, I did not find the FAULT3 pin in the UCD3138 manual.What is the pin number?
Thank you

over 7 years ago

0 zoujiangyilang over 7 years ago

Genius 4560 points

I have another question about GioRegs.FAULTIN.bit.FLT3_IN == 0.
I know that FAULTIN is the register name and bit.FLT3_IN is the name of the bit.
But I don't know what GioRegs means and what does it do?
I found that all registers are similar, such as MiscAnalogRegs., TimerRegs, Dpwm2Regs, and so on.

0 Yitzhak Bolurian over 7 years ago

TI__Mastermind 18370 points

if // removed, them the "GPIO ROM back door" will work.
Please note, there always will be another ROM back door using the PMBus command.
That one is not commented out.

0 Yitzhak Bolurian over 7 years ago in reply to zoujiangyilang

TI__Mastermind 18370 points

All of these structures have 3 parts.
The left part is the name of peripheral. The middle part is the name of the register belonging to that peripheral. The part at right is the name of the bitfield belonging to that register.

0 zoujiangyilang over 7 years ago in reply to Yitzhak Bolurian

Genius 4560 points

Got it! Thank you !

0 zoujiangyilang over 7 years ago in reply to Yitzhak Bolurian

Genius 4560 points

Hello
I did not find the FAULT3 pin in the 40-pin UCD3138, so the code here shields this function.
So where is PMBus's back door in the firmware?

0 Yitzhak Bolurian over 7 years ago in reply to zoujiangyilang

TI__Mastermind 18370 points

True, FAULT3 will not be good for 40 pin UCD. You may use another GPIO that is available/free in your application.
pmbus_write_rom_mode() function inside the file pmbus_common.c in the driver folder invokes the PMBus back door.
This in turn calls the clear_intergrity_word() which is not a regular function and actually is implemented by case 12 inside the software interrupt

0 zoujiangyilang over 7 years ago in reply to Yitzhak Bolurian

Genius 4560 points

Got it！Thank you！

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UCD3138: Questions about the back door in UCD3138 full-bridge hard-switch firmware