CC2538 Multiple PWM Signals Z-Stack

I write an example based on SampleLight using 4 PWM to change different level on LED1/LED2/LED3/LED4 of SmartRF06EB. You can refer to PWM_EVT in zcl_sampleLight.c. Remember to define HAL_PWM in your project  toenable PWM capability.

PWMonSampleLight.zip

Thanks for sending the files YiKai,

I see that the files sent require other Z-Stack Light files such as hal_timer.c When I added it to my ZStack Energy project for CC2538, it has many errors when I compile, and I think this is because hal_timer is written for the CC2530, and so many of the definitions do not match.

Is there a cc2538 version of hal_timer.c that you know of?

Actually, those files are for CC2538. You can download Z-Stack Home 1.2.2a and try it. I just test it and it works fine.

Ok thanks YiKai, I was looking in ZStack Light, I didn't think to try ZStack Home. My ZStack Energy now compiles with no errors with hal_timer.c included. I'll experiment with the code and see what happens.

You are welcome.

Hi YiKai, 

Thanks for the past help on this PWM issue. We are trying to use it in our project again and have a few issues:

We were hoping to generate 4 separate PWM signals. The firmware seems to have everything in place for this, except for one: It seems that the function halTimer1SetChannelDuty (found in Z-Stack home & Z-Stack light, and your example code files) has only been written for one PWM channel. Or did I miss something?

All other posts regarding the use of 4 PWMs and CC2538 seem to have the same issue.

Was the intention that one edits this function so that it can control 3 more PWMs if desired, by using the other timers and their related setup & control functions?  If this is the case, then my concern is that I interfere with the SoC's timer control.

Thanks for your time!

I don't understand your question well. Can you elaborate?

Yes of course: The function ...

void halTimer1SetChannelDuty (uint8 channel, uint16 promill)
{
if(channel == 0)
{
uint32 timerAMatch = (PWM_PERIOD * (100-promill)) / 100;

if(timerAMatch == PWM_PERIOD)
{
timerAMatch--;
}

//
// The PWM counter counts down thus calculate actual match count based
// on duty cycle as: period*(100-DucyCycle)/100
//
TimerMatchSet(GPTIMER0_BASE, GPTIMER_A, timerAMatch);
}
}

... seems to be written for only one PWM channel. If we wanted to add in 3 other PWM channels, would we have to add extra "if" statements? ( if(channel == 1) ... if(channel == 2) ... if(channel == 3) ) ?

It looks you have to do this. I don't have CC2538DK to test it right now. You can try it and let me know the result.

Ok thanks I'll try it.

Do I have access to timer-B, timer-C, and timer-D ??

I'm concerned that I will break the SoC system, by taking control of one of the timers that the SoC system uses.

As I know, all timer A, B, C, and D are for general usage and application should be no problem to use them.

Thanks YiKai, everything looks good, I have made all four general-purpose timers into separately controllable PWM's, and they work well. 

The function below shows how I set it up:

/************************************************************************************
* @fn pwmTimersInit
*
* @brief Configures the 4 general purpose timers for use as 4 separate PWMs
*
* @param n/a
*
* @return n/a
**********************************************************************/

void pwmTimersInit(void)
{
//CLOCK SETUP
SysCtrlClockSet(false, false, SYS_CTRL_SYSDIV_32MHZ); //Set the clocking to run directly from the external crystal/oscillator. (no ext 32k osc, no internal osc)
SysCtrlIOClockSet(SYS_CTRL_SYSDIV_32MHZ); //Set IO clock to the same as system clock. */
SysCtrlPeripheralEnable(SYS_CTRL_PERIPH_GPT0); //The Timer peripheral must be enabled for use.


//TIMER SETUP
TimerConfigure(GPTIMER0_BASE, GPTIMER_CFG_SPLIT_PAIR | GPTIMER_CFG_A_PWM | GPTIMER_CFG_B_PWM); // Configure GPTimer0A as a 16-bit PWM Timer.
TimerLoadSet(GPTIMER0_BASE, GPTIMER_A, PWM_PERIOD );
TimerControlLevel(GPTIMER0_BASE, GPTIMER_A, true);

TimerConfigure(GPTIMER1_BASE, GPTIMER_CFG_SPLIT_PAIR | GPTIMER_CFG_A_PWM | GPTIMER_CFG_B_PWM); // Configure GPTimer1A as a 16-bit PWM Timer.
TimerLoadSet(GPTIMER1_BASE, GPTIMER_A, PWM_PERIOD );
TimerControlLevel(GPTIMER1_BASE, GPTIMER_A, true);

TimerConfigure(GPTIMER2_BASE, GPTIMER_CFG_SPLIT_PAIR | GPTIMER_CFG_A_PWM | GPTIMER_CFG_B_PWM); // Configure GPTimer2A as a 16-bit PWM Timer.
TimerLoadSet(GPTIMER2_BASE, GPTIMER_A, PWM_PERIOD );
TimerControlLevel(GPTIMER2_BASE, GPTIMER_A, true);

TimerConfigure(GPTIMER3_BASE, GPTIMER_CFG_SPLIT_PAIR | GPTIMER_CFG_A_PWM | GPTIMER_CFG_B_PWM); // Configure GPTimer3A as a 16-bit PWM Timer.
TimerLoadSet(GPTIMER3_BASE, GPTIMER_A, PWM_PERIOD );
TimerControlLevel(GPTIMER3_BASE, GPTIMER_A, true);

//PIN SETUP PB3 ( Done under configIOStartup() )
IOCPinConfigPeriphOutput( GPIO_B_BASE, GPIO_PIN_3, IOC_MUX_OUT_SEL_GPT0_ICP1 ); // Configure GPIOPortB3 as the Timer0 output
GPIOPinTypeTimer( GPIO_B_BASE, GPIO_PIN_3 ); // Tell timer to use GPIOPortB3, Direction Selection and PAD Selection
IOCPadConfigSet( GPIO_B_BASE, GPIO_PIN_3, IOC_OVERRIDE_OE );

IOCPinConfigPeriphOutput( GPIO_B_BASE, GPIO_PIN_4, IOC_MUX_OUT_SEL_GPT1_ICP1 ); // Configure GPIOPortB4 as the Timer1 output
GPIOPinTypeTimer( GPIO_B_BASE, GPIO_PIN_4 ); // Tell timer to use GPIOPortB4, Direction Selection and PAD Selection
IOCPadConfigSet( GPIO_B_BASE, GPIO_PIN_4, IOC_OVERRIDE_OE );

IOCPinConfigPeriphOutput( GPIO_B_BASE, GPIO_PIN_1, IOC_MUX_OUT_SEL_GPT2_ICP1 ); // Configure GPIOPortB1 as the Timer2 output
GPIOPinTypeTimer( GPIO_B_BASE, GPIO_PIN_1 ); // Tell timer to use GPIOPortB1, Direction Selection and PAD Selection
IOCPadConfigSet( GPIO_B_BASE, GPIO_PIN_1, IOC_OVERRIDE_OE );

IOCPinConfigPeriphOutput( GPIO_B_BASE, GPIO_PIN_2, IOC_MUX_OUT_SEL_GPT3_ICP1 ); // Configure GPIOPortB2 as the Timer3 output
GPIOPinTypeTimer( GPIO_B_BASE, GPIO_PIN_2 ); // Tell timer to use GPIOPortB2, Direction Selection and PAD Selection
IOCPadConfigSet( GPIO_B_BASE, GPIO_PIN_2, IOC_OVERRIDE_OE );

//INTERRUPT SETUP
IntMasterEnable(); // Enable processor interrupts.

// Enable GPTIMER0_BASE, GPTIMER1_BASE, GPTIMER2_BASE, GPTIMER3_BASE, by referencing GPTIMER_A each time.
TimerMatchSet( GPTIMER0_BASE, GPTIMER_A, 0 ); //0%, Default to load-OFF
TimerEnable(GPTIMER0_BASE, GPTIMER_A);

TimerMatchSet( GPTIMER1_BASE, GPTIMER_A, 0 ); //0%, Default to load-OFF
TimerEnable(GPTIMER1_BASE, GPTIMER_A);

TimerMatchSet( GPTIMER2_BASE, GPTIMER_A, 0 ); //0%, Default to load-OFF
TimerEnable(GPTIMER2_BASE, GPTIMER_A);

TimerMatchSet( GPTIMER3_BASE, GPTIMER_A, 0 ); //0%, Default to load-OFF
TimerEnable(GPTIMER3_BASE, GPTIMER_A);

}

Nominal control of the PWM signals are done by using:

TimerMatchSet( GPTIMERx_BASE, GPTIMER_A, z );   

... where x is the timer base 0-3, and z is the desired duty cycle from 0-100.

and ..

TimerLoadSet( GPTIMER0_BASE, 0x68 ); 

...controls the period. I found that using 0x68 allows a duty cycle step increase of approximately 1%.

I did not have a chance to measure the frequency with 0x68 set, but it is somewhere between 200 and 600 kHz.

Cool and Thanks for sharing this back.