A question on F28054M LOCKDAC register DAC5LOCK bit

Hardy Hu

Other Parts Discussed in Thread: TMS320F28054M, MOTORWARE

Dear, C2K champs,

A customer is using TMS320F28054M, but we find that after calling the Device_cal(), the DAC5LOCK bit in LOCKDAC register will be set. This action causes we can't configure the DAC5CTL. So we have some questions need you help to answer:

Can we use the DAC5 and how to clear the DAC5LOCK bit after the Device_cal()?

Thanks and best regards,

Hardy Hu

over 9 years ago

0 caiwang zhang over 9 years ago

Prodigy 70 points

Thanks Hardy Hu.

I am the customer facing the problem.

There are a little more informations .

1) chip versioin is rev A.

2)I am ready to use this part, and need to set those registers:DAC5CTL,CTRIPPFCOCTL,AMP_PFC_GAIN. But i fail to set those registers,whatever i set,registers keep 0.

3)After debug,i find. After loading program(the program is provided in motorware_1_01_00_15),relative BITS in LOCKDAC,LOCKCTRIP,LOCKAMPCOMP is setted,as follow:

4)When i run CPU reset by CCS6.1,relative BITS in LOCKDAC,LOCKCTRIP,LOCKAMPCOMP is reset,but i find that this function can set relative BITS in LOCKDAC,LOCKCTRIP,LOCKAMPCOMP. as follow:

if i make a change to the program as follow, it work,and success to set relative BITS in LOCKDAC,LOCKCTRIP,LOCKAMPCOMP:

my problem is :

a.value after reset of the DAC5LOCK BIT is 1 or 0?reference manual offer this:

b.how to configure DAC5CTL,CTRIPPFCOCTL,AMP_PFC_GAIN registers correctly?

Thanks and best regards,

Cai Zhang

0 tlee over 9 years ago in reply to caiwang zhang

TI__Guru 62975 points

Cai,

The images in your post are unfortunately not showing up on my screen so I cannot comment on their contents.

My understanding is that the F28054M device variant will intentionally lock DAC5 during the boot process.

I am not sure as to the specific reasons behind this (for example if it is required by InstaSPIN), but I believe that you are seeing normal behavior.

-Tommy

0 caiwang zhang over 9 years ago in reply to tlee

Prodigy 70 points

PFC Problem.pdf

0 caiwang zhang over 9 years ago in reply to caiwang zhang

Prodigy 70 points

Thanks Tommy,
i attach pictures in pdf file.

0 tlee over 9 years ago in reply to caiwang zhang

TI__Guru 62975 points

I believe that your screenshots are consistent with expected behavior.

On reset or power up, the LOCK registers are cleared to 0. The LOCK bits may be set through software (boot or application code), which would lock out write access to the associated registers. There is no way to modify the contents of locked registers without a device reset or power cycle.

0 caiwang zhang over 9 years ago in reply to tlee

Prodigy 70 points

Thanks to your quickly reply.

As you say, The LOCK bits may be set through software (boot or application code), can i set this registers through boot ?

0 tlee over 9 years ago in reply to caiwang zhang

TI__Guru 62975 points

By boot, I mean the device hardware boot ROM, which cannot be modified. You can set additional LOCK bits to 1 in your application code as needed.

A LOCK bit set to 1 can only be cleared to 0 by a device reset.

0 caiwang zhang over 9 years ago in reply to tlee

Prodigy 70 points

I know i can set relative LOCK BITs if i need lock some registers, but if relative BITS in LOCKDAC, LOCKCTRIP, LOCKAMPCOMP is setted by boot, i cann`t set DAC5CTL,CTRIPPFCOCTL,AMP_PFC_GAIN register, however i can set those registers by ccs CPU Reset, can i achive the function by software?

Thanks

0 tlee over 9 years ago in reply to caiwang zhang

TI__Guru 62975 points

No, software alone would not be enough to unlock the registers.

As you have discovered, this would require some hardware intervention like resetting through CCS and halting CPU execution before the boot ROM can execute.