topic Re: Time measurement in CodeWarrior for MCU

Time measurement

juliancox — Mon, 03 Jul 2017 22:54:09 GMT

I am having a problem with time measurement in an application that I am developing using a S08SH. I am using (Processor Expert) FC1:FreeCntr with timer TPM10 to generate an interrupt every 5mS. This works fine. I am then trying to use FC161:FreeCntr16 with timer TPM20 to measure a time interval: -

In the FC1:FreeCntr ISR I start the FC161 timer. A separate software event stops the timer and I read the elapsed time - except that it doesn't work.

To investigate the problem I created a simple simulation project.

void FC1_OnInterrupt(void)

{

unsigned char r,s;

unsigned int Time;

r = FC161_Enable();

for(s=0;s<50;s++); // a simple delay loop

Time = TPM2CNT; // read the ticks

r = FC161_Reset(); // set the breakpoint here

r = FC161_Disable();

}

The value in TPM2CNT was always wrong and the only it would work was if I set a breakpoint somewhere in the ISR and then manually changed registers TPM20SC from 0xD0 to 0x50 and TPM2MOD from 0x0003 to 0xFFFF.

TPM2CNT then held a value that related to the duration of the simple delay loop. However, I cannot find a way to set these register values for FC161:FreeCntr16 using the component Inspector in Processor Expert.

Re: Time measurement

juliancox — Tue, 04 Jul 2017 11:06:46 GMT

Further to the above it appears that the only register that I have to change is TPM2MOD. I was able to change the value by changing the FC161 resolution from 1uS (3) to 16mS (0xF9FF), but I don't know if this is the correct way to do things. All I want is a counter that will start when software tells it to start and stop when software tells it to stop, at which point software can read the number of ticks.

Re: Time measurement

ZhangJennie — Wed, 05 Jul 2017 06:09:20 GMT

Hi Cox.

To check your problem we need more information.

1. your CW version:
- if you use classic version: Start the IDE and click on Help | About Freescale CodeWarrior. Click on Installed Products.Save all info displayed into a txt file and send it to me.
- if you use eclipse version: Start the IDE and click on Help | About CodeWarrior Development Studio. Send me the version and build id.

2. your demo project.

Thus I can test it directly from my side.

Thanks.

Have a great day,
Jennie Zhang

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Re: Time measurement

juliancox — Wed, 05 Jul 2017 10:03:26 GMT

Hi Jennie, please call me Julian - it sounds less formal.

My CW installation is Version 10.7 Build Id: 160721

I hope I have done the next step correctly - I have never used this facility

I used the export wizard > Export | General | Archive file

I selected the project in the left hand window and all files in the right hand window.

Re: Time measurement

juliancox — Wed, 12 Jul 2017 10:06:37 GMT

Hi Jennie

Any signs of a solution?

Re: Time measurement

ZhangJennie — Fri, 14 Jul 2017 09:50:01 GMT

Hi Julian,

Sorry for the late, I was not in office this week thus I don't have a SH4 board in hand now.

However I checked your code you use FreeCntr16 component tor TPM2 counting. This is counter for long time period. I suggest you use FreeCntr for TPM2 instead. See how it works?

I will test your code with board once I get to office next week.

Have a great day,
Jennie Zhang

Re: Time measurement

juliancox — Mon, 17 Jul 2017 08:28:00 GMT

Thanks for the reply.

Perhaps you could explain: - If I am reading the value in TPM2 count register - that contains the number of ticks since I enabled FreeCntr16 so is that not the most accurate measurement possible? If i only need a 16-bit result and no interrupt, Is there a method to start, stop and reset TPM2 directly so that I don't need FreeCntr16 at all? In real time the elapsed time will be between 0.5mS and 15mS.

Re: Time measurement

ZhangJennie — Fri, 21 Jul 2017 09:23:35 GMT

Hi Julian

I finally found a board to test your project. here is my testing result

here, I set breakpoint at FC161_Reset()

in Variable window: Time is 0x223

in Registers window: TPM2CNT is 0x0227

these two values are different. This is because the program runs from previous line to FC161_Reset() takes a few clock.

Please let me know what else you think abnormal.

Have a great day,
Jennie Zhang