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Background
I’m building a test fixture based on the TM4C that will be used to automate certain functionality for TI’s mmWave based platforms. The main communication between the test fixture (TM4C) and mmWave device is UART. With that said, before I dive in, I wanted to verify a couple assumptions with regard to TivaWare, DriverLib, and the relationship with TI-RTOS.
That’s quite a broad topic, so to narrow the scope, the focus of this question will be in relation to UART specifically.
Thought Process
At a high level, I see three libraries at play;
Question:
Is it correct to say, the standard DriverLib library from TivaWare is not thread safe. For this reason, a subset of drivers are provided within TI-RTOS-TivaC, which is thread safe. These are the drivers found within \ti\drivers, for example ti\drivers\UART.h?
In terms of DriverLib, maybe the bundled version found within tirtos_tivac (C:\ti\tirtos_tivac_2_16_00_08\products\TivaWare_C_Series-2.1.1.71b\driverlib) is the one the developer should use, instead of reaching directly into C:\ti\tivaware? I'll have to diff the DriverLib version found within TI-RTOS, versus the standard TivaWare DriverLib, to see if there's any differences.
So in summary, when developing an application within TI-RTOS for the TM4C, which drivers are you allowed to use. Should you only try to exclusively use the subset of RTOS drivers, or is it fine to directly use DriverLib drivers? Also, kind of along the same lines, do you omit the ROM_ or MAP_ directives in general, as the RTOS probably internally maps these already?
Example:
To bring things full circle, I figured an example would be best.
Imagine you are leveraging DMA to facilitate serial comms over UART. One option provided within DriverLib’s implementation of uDMA, is to setup a ping-pong style Control Mode via UDMA_MODE_PINGPONG, using both primary and secondary buffers for storage.
However, TI-RTOS for Tiva does not have such functionality in their UARTivaDMA driver, so maybe that’s a case where you’re on your own?
I think once I understand the basic concept of what can and can’t be used, then the rest of the puzzle pieces should fall into place.
Thanks!
Hi,
Is it correct to say, the standard DriverLib library from TivaWare is not thread safe.
Your understanding is correct. TivaWare is not thread-safe but you can use synchronization to protect multiple threads that access the same TivaWare APIs.
For this reason, a subset of drivers are provided within TI-RTOS-TivaC, which is thread safe. These are the drivers found within \ti\drivers, for example ti\drivers\UART.h?
Yes, TI-RTOS is thread-safe. However, the reason that only a subset of drivers are provided within TI-RTOS is because it achieves the common denominator for all TI products. Image there are many different UART implementations across different TI products, these TI-RTOS drivers have the same interface across all TI products. Special or advance features are not built into the TI-RTOS drivers.
In terms of DriverLib, maybe the bundled version found within tirtos_tivac (C:\ti\tirtos_tivac_2_16_00_08\products\TivaWare_C_Series-2.1.1.71b\driverlib) is the one the developer should use, instead of reaching directly into C:\ti\tivaware?
The underlying TivaWare version bundled with TI-RTOS version 2.16.0.18 is TivaWare version 2.1.1.71b. The reason is that 2.1.1.71b is the one that is fully validated. Newer versions of TivaWare can be used but they are not validated. You can go through the release note of the latest TivaWare version to know what changes have been made compared to prior versions.
So in summary, when developing an application within TI-RTOS for the TM4C, which drivers are you allowed to use.
If you are using TI-RTOS drivers, I will suggest you use the validated version for TI-RTOS which is 2.1.1.71b that is bundled with TI-RTOS.
Should you only try to exclusively use the subset of RTOS drivers, or is it fine to directly use DriverLib drivers?
If you are not going to use TI-RTOS drivers but rather TivaWare directly you can use the latest TivaWare version which is 2.2.0.295. Please use the necessary synchronization to protect for thread-safety.
Also, kind of along the same lines, do you omit the ROM_ or MAP_ directives in general, as the RTOS probably internally maps these already?
If you are calling TivaWare drivers directly, you can use MAP_ or ROM_.
Imagine you are leveraging DMA to facilitate serial comms over UART. One option provided within DriverLib’s implementation of uDMA, is to setup a ping-pong style Control Mode via UDMA_MODE_PINGPONG, using both primary and secondary buffers for storage.
However, TI-RTOS for Tiva does not have such functionality in their UARTivaDMA driver, so maybe that’s a case where you’re on your own?
Your understanding is correct. There are also TM4C modules that do not have TI-RTOS drivers for them. For example, CAN, ADC, QSSI, LCD and many others. You will need to use TivaWare drivers within TI-RTOS.
