LP-CC1352P7: timer event capture

Hi Karthik,

You could use our GPTimer driver, and its "input time" mode:

https://dev.ti.com/tirex/explore/content/simplelink_cc13xx_cc26xx_sdk_7_10_01_24/docs/drivers/doxygen/html/_g_p_timer_c_c26_x_x_8h.html

We do not have an example to provide unfortunately.

Regards,

Arthur

Hi Arthur,

Thanks for sharing the documentation. I already looked at it and could not implement it.

Appreciate if you could provide an example.

Thanks

Karthik

Hi Karthik,

Please have a look at the initEdgeTimer described here: https://e2e.ti.com/support/wireless-connectivity/sub-1-ghz-group/sub-1-ghz/f/sub-1-ghz-forum/907854/cc2652r-gptimercc26xx-timeout-interrupt-when-in-gpt_mode_edge_time_up

It also shows the caveats you might encounter along your way.

Regards,

Arthur

Hi Arthur,

How to capture the GPTimer value just when it is about to reach the load value?

For example. load value of the timer is 47999999 ( to generate interrupt every 1 second).

Trying to read the timer value using " GPTimerCC26XX_getValue" API across the application at various stages.

in the timer callback function, tried to read the same and noticed that the timer value is too low. Does not match or close to load value.

Is there anyway to read the maximum load value(or something closer to load value) of the timer?

Attached source code file for reference(the 802.15.4 based radio is intended to transmit every 1 second). Used capture_timer_count variable to read timer value at few locations in the code. Did the same in timer call back but could not understand if the value reached the loaded value.

rfPacketTx_Transmit_every1second.zip

Hi Karthik,

Sorry about the delay.

It looks like that by the time the application enters the timerCallback, the value inside the timer is already different that the timer value.

This is normal behavior as the timer does not stop to generate the timer callback.

Why do you need to get the capture timer count? You can assume that the timerCallback will execute as the correct interval. You can verify this by togging a GPIO in your timer callback, and observe the period using a logic analyzer/oscilloscope.

Regards,

Arthur

Hi Arthur,

I need to initiate few events (time slice) and take action when a counter reaches a certain value.

Hence, needed to know how to keep track of the counter value at various stages in my code.

For example, MSP430 supports capture compare timer mode and was easy to act on events based on its interrupts. Is there an equivalent in this chip?

Thanks

Karthik

Hi Karthik,

I understand that this is the way to do it on an MSP430.

However, you could leave that time keeping to the RTOS/Timer driver, which will schedule those events for you.

For instance, given you have to schedule several events in the future, you could use Timer.h in ONE_SHOT_CALLBACK mode:

https://dev.ti.com/tirex/explore/node?node=A__AD0ghBnDPMQSci35.HFlFA__com.ti.SIMPLELINK_CC13XX_CC26XX_SDK__BSEc4rl__LATEST

And schedule a callback for each of those events, and eventually trigger it again when needed.

Regards,

Arthur

Hi Arthur,

What is the difference between checking and unchecking GPTimer ?

I can see ti_drivers_config.h to have constants defined for Timer and GPTimer

Thanks

Karthik

Awaiting response to this.

Hi Arthur,

Section: 15.3.2.3 Input Edge-Time Mode

https://www.ti.com/lit/ug/swcu192/swcu192.pdf?ts=1689167061633&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FCC2652R7

Looks like we can set an up-counter from zero to whatever value we choose, and can set an event capture as the intermediary steps within the time window.

You pointed me to a discussion about this mode in your earlier responses. But the discussion doesn't seem to be conclusive and I am not sure if that worked or not.

Could you please provide an example on how to use the GPTimer in this mode?

Thanks

Karthik

Hi Karthik,

As indicated in SysConfig, the GPTimer check box allows you to select between the following drivers:

• Timer.h/TimerCC26XX.c: This is a portable driver, meaning that you could reuse code you write with those devices accross other TI devices.
• GPTimerCC26XX.c: This driver gives you access to more features and more control on the peripheral, that are CC26XX specific, and thus non portable to other TI devices.

As of your other question, I have to read more about it, but I will find an answer.

Regards,

Arthur