LAUNCHXL-CC1352R1: Problems with timer accuracy

Hi Clark,

Regarding driverlib, this is common for TIRTOS and nortos. You can find the documentation here. As you said, if you want to use driverlib APIs please make sure you don't create any conflicts with TI RTOS or TI drivers.

For the rest of the questions please allow us some days to investigate.

Please note that with respect to accuracy, the GPTimer clock is dependent on the MCU system clock. If very high-accuracy outputs are needed, the application should request using the external HF crystal:

#include <ti/sysbios/family/arm/cc26xx/Power.h>
#include <ti/sysbios/family/arm/cc26xx/PowerCC2650.h>

Power_setDependency(XOSC_HF);

BR

Siri

Hi Marie, 

Thank you for your prompt reply!

Unfortunately, I don't understand a couple things regarding your reply.

1. You referenced the CC26xx driver library. This is not the same timer.h file used in the timerled example app which is a tirtos app. The CC26xx library appears to have many more features. So can I use the CC26XX driver library instead of whatever is used in the example app? Is the example app using the wrong driver library? If I can use the CC26XX library, how do I include it?

2. You typed "if you want to use driverlib APIs please make sure you don't create any conflicts with TI RTOS or TI drivers." You also said the CC26XX driver "is common for TIRTOS and nortos". Since it is common for both, if I use this driver, how is it even possible to create a conflict?

Obviously, I am confused! What I am trying to figure out is what driver do I use for TIRTOS and what driver do I use for nortos. And furthermore, how can I avoid creating any conflicts with TIRTOS or TI drivers?

Thank you for your help and I look forward to your reply.

Thank you for this information, Siri. I will add this code today and see if it improves my accuracy. 

Siri

Your advice to get the external HF crystal turned on was very helpful. Now my LaunchPad is setting the times very accurately...probably beyond the accuracy of my oscilloscope.

I am using the following code on the LAUNCHXL-CC1352R1:

#include <ti/drivers/Power.h>
#include <ti/drivers/power/PowerCC26X2.h>
#include <ti/drivers/power/PowerCC26XX.h>
#include <ti/devices/cc13x2_cc26x2/driverlib/osc.h>

// Guarantees that we are running on the external crystal
Power_setConstraint(PowerCC26XX_DISALLOW_XOSC_HF_SWITCHING);
Power_setDependency(PowerCC26XX_XOSC_HF);
while(!PowerCC26XX_isStableXOSC_HF());
PowerCC26XX_switchXOSC_HF();

Thank you for this tip! Now I just need to get my remaining questions answered. THANK YOU AGAIN!

Hi Clark

I will try to explain:

You have the DriverLib and the TI Drivers.

DriverLib is a set of low level drivers for accessing the registers found on the CC26xx family of ARM® Cortex™-M based devices. The DriverLib functions are grouped in APIs based on either specific on-chip peripheral module (e.g. SPI, UART, etc ) or more general functionality (e.g. system control, oscillator settings, etc). Each API uses a unique pre-fix for all the DriverLib functions in that API to indicate which module or type of functionality being accessed (with a few exceptions).

The TI Drivers is a collective of peripheral drivers for TI's SimpleLink portfolio. The drivers are centered around a portable application programming interface (API) which enables seamless migration across the SimpleLink SDK portfolio.

All our code examples are using the TI Drivers (which is what we recommend), and the TI Drivers use the DriverLib (I know the name DriverLib can be confusing, since this is not actual drivers, but simply an abstraction layer for accessing registers).

For the TI Drivers, they can be used for both TI-RTOS and nortos.

In some cases, the TI Drivers will not support the use case for a peripheral that you need (even if the HW is capable of supporting this). In these cases, it can be necessary to use DriverLib to configure the peripheral in a certain way, or simply creating your own driver by using the DriverLib API.

When Marie said you had to be careful to avoid conflict, I think she just meant that if you start modifying registers etc. directly using DriverLib, you have to make sure that you are not getting into conflict with registers that needs to be set a certain way if you are also using the TI Drivers.

I hope this made things a bit clearer.

BR

Siri

Siri

That was very helpful! Only a couple remaining questions from my original post:

1. Is NO-RTOS the same as bare metal? If not, what are the differences between NO-RTOS and bare metal?

2. If I wanted to use TI RTOS but I did not want to use TI Drivers because a certain functionality was not supported, where are the DriverLib libraries? And where are the TI Driver libraries? I am using a LaunchXL-CC1352R1 and CCS. In the CCS Project Explorer Includes folder, there is an [SDK]/source/ti folder. Are the TI Driver and DriverLib libraries inside that folder? Where are each of them located?

3. Similarly if I wanted to use noRTOS, where are the TI Driver and DriverLib libraries for noRTOS?

4. Lastly, in the timer section of SysConfig, I see there is a checkbox that says Use GPTimer. What does this do?

Clark