RTOS/TM4C1294NCPDT: TM4C1294NCPDT, PWM with TIRTOS API.

Doug Baker

Part Number: TM4C1294NCPDT

Tool/software: TI-RTOS

I am using a TM4C1294NCPDT with CCS 6.1.2 and TIRTOS 2.16.0.08.

On the TM4C1294NCPDT, I want to use PWM1 on PIN PF1, PWM2 on pin PF2 and PWM3 on pin PF3. I found an example app called pwmled.c and used that on an eval board and everything worked well but I have some questions about using the API used in the example in my project.

The example app pwmled.c used PWM0 and API calls:

PWM_Params_init() PWM_open() PWM_setDuty()

My questions

1) where do I find the detailed documentation of the API calls PWM_Params_init() PWM_open() PWM_setDuty()?

2) In the sample application pwmled.c, the init is called with the following params PWM_open(Board_PWM0, &params);

In board.h, I see #define Board_PWM0 EK_TM4C1294XL_PWM0

And in EK_TM4C1294XL.h I see:

typedef enum EK_TM4C1294XL_PWMName {

EK_TM4C1294XL_PWM0 = 0,

EK_TM4C1294XL_PWMCOUNT

} EK_TM4C1294XL_PWMName;

As you can see above, the PWM channels 1-3 are not defined in EK_TM4C1294XL.h where PWM ch 0 is.

What is the recommended way to add the other PWM1, PWM2 and PWM3 to the project or should I use the TIVA API using described in the peripheral drive library instead?

The the TIVA API would use functions PWMGenConfigure(), PWMPeriodSet(), PWNPulseWidthSet() etc...

Thanks,

Doug

over 7 years ago

0 Charles Tsai over 7 years ago

TI__Guru**** 183006 points

Hi Doug,
I think your questions can be answered in section 5.9 on the PWM Driver of the TI-RTOS User's Guide. Normally you can find the documentation in your <TI-RTOS Installation>/docs/Users_Guide.pdf. Here is also the link to it. www.ti.com/.../spruhd4m.pdf
Please also visit the TI-RTOS wiki page for additional information. processors.wiki.ti.com/.../TI-RTOS

If you want to use the TI-RTOS to manage the PWM functions, you will need to update the typedef enum EK_TM4C1294XL_PWMName to include the additional PWM pins you want to use. Likewise, you will need to update the EK_TM4C1294XL.c as well under the PWM section.

You may also use the TivaWare PWM APIs and use the TI-RTOS's Hwi to manage the PWM interrupts.

0 Doug Baker over 7 years ago in reply to Charles Tsai

Genius 3400 points

I did have the document you shared in the link www.ti.com/.../spruhd4m.pdf
but I didn't see where it described the params and the limits etc or the params. The document references
links for more info for example <tirtos_install>\products\tidrivers_,version>\docs\html\index.html.
I did look around for that path or similar path but I didn't find the additional details I was looking for.
I think in the end I can reference the CPU doc for any additional information I need on the params.

I did add some code to EK_TM4C1294XL.c and EK_TM4C1294XL.h for the PWM devices 1,2, and 3

typedef enum EK_TM4C1294XL_PWMName {
    EK_TM4C1294XL_PWM0 = 0,

   EK_TM4C1294XL_PWM1, // added for pwm1
   EK_TM4C1294XL_PWM2, // added for pwm2

    EK_TM4C1294XL_PWM3, // added for pwm3

    EK_TM4C1294XL_PWMCOUNT
} EK_TM4C1294XL_PWMName;

const PWMTiva_HWAttrs pwmTivaHWAttrs[EK_TM4C1294XL_PWMCOUNT] = {
    {
        .baseAddr = PWM0_BASE,
        .pwmOutput = PWM_OUT_0,
        .pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_RUN,

        .baseAddr = PWM1_BASE,
        .pwmOutput = PWM_OUT_1,
        .pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_8000RUN,

        .baseAddr = PWM2_BASE,
        .pwmOutput = PWM_OUT_2,
        .pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_RUN,

        .baseAddr = PWM3_BASE,
        .pwmOutput = PWM_OUT_3,
        .pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_RUN
    }
};

#define Board_PWM0                  EK_TM4C1294XL_PWM0
#define Board_PWM1                  EK_TM4C1294XL_PWM1
#define Board_PWM2                  EK_TM4C1294XL_PWM2
#define Board_PWM3                  EK_TM4C1294XL_PWM3

#define PWM0_BASE               0x40028000 // Pulse Width Modulator (PWM)
#define PWM1_BASE               0x40029000 // Is this correct ??
#define PWM2_BASE               0x4002A000 // Is this correct ??
#define PWM3_BASE               0x4002B000 // Is this correct ??

I think the only question I have still is confirming the base address is correct for PWM1-PWM3. From
this document www.ti.com/.../tm4c1294ncpdt.pdf I see in section 23.5 that PWM0 was
defined as 0x4002.800. On page 104 / Table 2-4 memory Map of that same document there is a table with the addresses of the
devices but I was not able to confirm the base address of PWM1-PWM3 since I didn't see the base address
for PWM1-PWM3 listed.

Thanks,

Doug

0 Charles Tsai over 7 years ago in reply to Doug Baker

TI__Guru**** 183006 points

Hi Doug,
I'm not a TI-RTOS expert. However, looking at the PWMTiva.h and the TI-RTOS document software-dl.ti.com/.../_p_w_m_tiva_8h.html for Tiva device, I'm suspicious what you are doing is correct (i.e. assigning addresses for different PWM generators).

It seems to me that you might want to try below instead where the base address is PWM0_BASE for all of them. The reason is that there is only one PWM module in the device. The single PWM module contains four PWM generators with each supports two PWM pins.

.baseAddr = PWM0_BASE,
.pwmOutput = PWM_OUT_1,
.pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_8000RUN,

.baseAddr = PWM0_BASE,
.pwmOutput = PWM_OUT_2,
.pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_RUN,

.baseAddr = PWM0_BASE,
.pwmOutput = PWM_OUT_3,
.pwmGenOpts = PWM_GEN_MODE_DOWN | PWM_GEN_MODE_DBG_RUN

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RTOS/TM4C1294NCPDT: TM4C1294NCPDT, PWM with TIRTOS API.