TMS570LC4357: Peripheral power down issue

Raushan Kumar1

Part Number: TMS570LC4357

Hi,

After reading all the documentation , I understand how the bits in the PCRx PSPWRDWNCLRx and PSPWRDWNSETx registers work.

After testing with the microcontroller, it seems that even if the clock to a peripheral(I2C) is inactive, I am able to write into the peripheral(I2C) registers.

What I see is that when I set the PSPWRDWNSET registers(where Quadrants Quad0 of PS[10] clock is inactive for I2C), i am able to read ,write data using I2C. I was expecting that if the I2C were not clocked, as supposed by the PSPWRDWN configuration, the I2C could not output any signal or even the access to its registers wouldn't be possible.

So I have questions related to this topic:

After disabling clock to I2C via power down set register PSPWRDWNSET (PS[10],Quad0),still I2C is working..how??

over 5 years ago

0 Sunil Oak over 5 years ago

TI__Mastermind 49120 points

Hi,

The PCR does allow CPU write accesses to "go through" even if the clock is disabled to the peripheral. Essentially the clock is turned ON just for the duration of the write access and then turned OFF.

A read access to the peripheral will fail when the clock to that peripheral is disabled. You should get an abort response from the CPU in this case.

Regards, Sunil

0 Raushan Kumar1 over 5 years ago in reply to Sunil Oak

Prodigy 80 points

Hi Sunil,

Thanks for the quick response.

As you said read access will give abort response if clock is disabled.

I tried to read i2c register after disabling the i2c clock, m not getting any abort response.

Here the main issue is i2c is working even after clock is disabled through power down set register.

Is there any way to verify whether clock is disabled or enabled??

0 Sunil Oak over 5 years ago in reply to Raushan Kumar1

TI__Mastermind 49120 points

Which PCR are you configuring to gating off the peripheral clock to the I2C? There are three PCRs on this MCU. Clock to the I2Cx modules is controlled by the PC3 registers.

0 Raushan Kumar1 over 5 years ago in reply to Sunil Oak

Prodigy 80 points

Hi,

PCR3 (PS10, Quad0) I have configured to disable the i2c clock.

Is this OK?

0 Raushan Kumar1 over 5 years ago in reply to Raushan Kumar1

Prodigy 80 points

Hi Sunil,

After testing, I found not only I2C, This problem is there for other peripherals also like. SCI, ADC.

0 Sunil Oak over 5 years ago in reply to Raushan Kumar1

TI__Mastermind 49120 points

Sorry for the delay in responding, I was out of office the remainder of last week. I will check this and get back to you.

0 Raushan Kumar1 over 5 years ago in reply to Sunil Oak

Prodigy 80 points

Yes.. Please,

Thanks for your support.

0 Sunil Oak over 5 years ago in reply to Raushan Kumar1

TI__Mastermind 49120 points

I stated incorrectly. The peripheral interface clock is enabled for both write and read accesses even if the clock is gated off using the PCR PSPWRDWN registers. This allows the CPU to read / write the peripheral registers without causing an exception.

Arm-based microcontrollers

Arm-based microcontrollers forum

TMS570LC4357: Peripheral power down issue