TMS320F280039C: variable unexpected changed issue

jingbo gao

Tool/software:

We find one union variable be unexpected changed when software running.

Phenomenon

tPFC_Ctrl.Bit.OnOff is defined in CpuToCla1MsgRAM and will be unexpected changed.The code do not assignment 0 to tPFC_Ctrl.Bit.OnOff but it will be changed high speed to 0 and then recover to 1.

We use GPIO to observe tPFC_Ctrl.Bit.OnOff， it will changed irregular and every time it will recover in 20us.

The question

For this issue ,we find two way to solve.

1.close the compiler optimization(from 3 -> off).

2.use volatile keyword to define tPFC_Ctrl.

So the question are

1.why compiler optimization will let this issue happen？

2.How to use compiler optimization level to avoid this kind problem.

The other try

1.we try to redefine tPFC_Ctrl in Cla1ToCpuMsgRAM, the issue disappear. It means only CPU will let the issue happen not CLA.

2.we use const keyword to define tPFC_Ctrl, can only use pointer to access tPFC_Ctrl, the issue still exist.

over 1 year ago

0 Ozino Odharo over 1 year ago

TI__Mastermind 21600 points

Hi,

Can you confirm if it changes when you only specify it to be volatile. Keep the optimization at level 3. Can you confirm that this union is allocated to memory that is accessible to both the CLA and CPU.

Regards,

Ozino

0 jingbo gao over 1 year ago

Prodigy 15 points

1.it will not change when specify it to be volatile when optimization at level 3

2.i can confirm the union both accessible to CLA and CPU. (the union defined in CpuToCla1MsgRAM so that CPU can both read and wirte , CLA just can read.)

0 Ozino Odharo over 1 year ago in reply to jingbo gao

TI__Mastermind 21600 points

Hi,

I'll take a look at the CpuToCla1MsgRAM and get back to you with more information.

Regards,

Ozino

0 Ozino Odharo over 1 year ago in reply to Ozino Odharo

TI__Mastermind 21600 points

Hi,

Can you confirm if the tPFC_Ctrl function runs on the CLA or CPU? Is the GPIO mapped to the CPU or CLA?

Regards,
Ozino

0 jingbo gao over 1 year ago in reply to Ozino Odharo

Prodigy 15 points

1.the tPFC_Ctrl will be read or modified at CPU and only be read at CLA.

2.the GPIO observe function run at CPU.we use the TI lib register to operate GPIO like (GpioDataRegs.GPACLEAR.bit.GPIO29 = 1;).

0 jingbo gao over 1 year ago in reply to jingbo gao

Prodigy 15 points

For 2 : Actually this code is for power control use, tPFC_Ctrl will influence our control algorithm code.So at first we find our machine will shutdown no reason and then we use GPIO to locate the issue.

It means ,if observe the tPFC_Ctrl does not influence the unexpected changed Phenomenon.