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SalihLabs
Joined: 27 May 2020
Posts: 8
Location: Ontario, Canada
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| dsPIC33 HSPWM, phase-shift PG2 relative to PG1 not working |
 Posted: Tue May 30, 2023 11:35 pm |
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Hi all,
I'm using the dsPIC33CH512MP508, a dsPIC with a master and slave core. Currently using PCWHD 5.093.
The HSPWM configuration settings are based on the Microchip code example on github: https://github.com/microchip-pic-avr-examples/dspic33ck-power-pwm-phase-shift
I am able to generate a complimentary signal on PG1 and PG2, but unable to phase shift PG2 relative to PG1:
The example code on github shows what the phase shifted PG2 should look like:
| Code: |
void HSPWM_init(void)
{
// setup PG1
setup_hspwm_unit(1, HSPWM_ENABLE | HSPWM_USES_MASTER_CLOCK | HSPWM_HIGH_RESOLUTION_MODE |
HSPWM_COMPLEMENTARY | HSPWM_INDEPENDENT_EDGE_MODE |
HSPWM_SINGLE_TRIGGER_MODE | HSPWM_SOC_SELF_TRIGGERED );
#byte PG1EVTL = getenv("SFR:PG1EVTL") // PG1TRGSEL[2:0]
#byte PG1IOCONH = getenv("SFR:PG1IOCONH")
#byte PG1IOCONL = getenv("SFR:PG1IOCONL")
PG1EVTL |= 0x03; // PGxTRIGC is the PWM Generator Trigger Output
// PG1IOCONH |= 0x00; // UPDMOD = 0b00, TRGMOD = 0b0, SOCS = 0b0000
// PG1IOCONL |= 0x3000; // OSYNC = 0b00, OVRDAT = 0b00, OVRENL = 1, OVRENH = 1: 0b 0011 0000 0000 0000 = 0x3000
// setup PG2
setup_hspwm_unit(2, HSPWM_ENABLE | HSPWM_USES_MASTER_CLOCK | HSPWM_HIGH_RESOLUTION_MODE |
HSPWM_COMPLEMENTARY | HSPWM_INDEPENDENT_EDGE_MODE | HSPWM_BUFFER_UPDATE_SLAVED_IMMEDIATE |
HSPWM_RETRIGGERABLE_MODE | HSPWM_SOC_PWM1_5_PG1_OR_PG5 );
#byte PG2CONH = getenv("SFR:PG2CONH")
#byte PG2IOCONH = getenv("SFR:PG2IOCONH")
#byte PG2IOCONL = getenv("SFR:PG2IOCONL")
PG2CONH |= 0x01; // SOCS[3:0] = 0b0001 Start Of Cycle: PG1 selected trigger output triggers PG2 SOC
// must force disable all other irrelevant channels, otherwise you cant use shared IO pins
setup_hspwm_unit(3, HSPWM_DISABLE);
setup_hspwm_unit(4, HSPWM_DISABLE);
setup_hspwm_unit(5, HSPWM_DISABLE);
setup_hspwm_unit(6, HSPWM_DISABLE);
setup_hspwm_unit(7, HSPWM_DISABLE);
setup_hspwm_unit(8, HSPWM_DISABLE);
// set duty cycle
set_hspwm_duty(1, duty);
set_hspwm_duty(2, duty);
// set period
set_hspwm_period(1, pwmPeriod);
set_hspwm_period(2, pwmPeriod);
hspwm_update(1);
hspwm_update(2);
// start hspwm module
delay_us(200);
setup_hspwm(HSPWM_CLOCK_AFPLLO | HSPWM_CLOCK_DIV_BY_2, pwmPeriod);
}
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To vary the phase-shift in the main while loop, I tried both "set_hspwm_trigger_c" and modifying the PG1TRIGC SFR directly to no avail.
| Code: |
// SET Trigger limit
//set_hspwm_trigger_c(1, (unsigned int16)*(0.25*pwmPeriod));
#byte PG1TRIGC = getenv("SFR:PG1TRIGC")
PG1TRIGC = (unsigned int16)*(0.125*pwmPeriod);
//phase_adjust();
// Update
hspwm_update(1); // **
hspwm_update(2); // **
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Any ideas? |
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temtronic
Joined: 01 Jul 2010
Posts: 9241
Location: Greensville,Ontario
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| Posted: Wed May 31, 2023 5:52 am |
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curious as the example code works...
I was thinking 'compiler bug' but... noticed a 0.125 floating point number....
PG1TRIGC = (unsigned int16)*(0.125*pwmPeriod);
Maybe 'test the math' and SEE what numbers are really being generated ??
.125 is 1/8th, so could 'right shift pwmPeriod ,by 8' be better/faster ?? |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19536
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| Posted: Wed May 31, 2023 8:33 am |
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What you post, can only be compiled for the slave, since the master
only has four of these modules available.
I think the correct syntax for these settings using the CCS functions
is:
| Code: |
// setup PG1
setup_hspwm_unit(1, HSPWM_ENABLE | HSPWM_USES_MASTER_CLOCK | HSPWM_HIGH_RESOLUTION_MODE |
HSPWM_COMPLEMENTARY | HSPWM_INDEPENDENT_EDGE_MODE |
HSPWM_SINGLE_TRIGGER_MODE | HSPWM_SOC_SELF_TRIGGERED );
SETUP_HSPWM_EVENT(1,HSPWM_EVENT_TRIGGER_PGxTRGC,HSPWM_EVENT_INTERRUPT_DISABLED);
// setup PG2
setup_hspwm_unit(2, HSPWM_ENABLE | HSPWM_USES_MASTER_CLOCK | HSPWM_HIGH_RESOLUTION_MODE |
HSPWM_COMPLEMENTARY | HSPWM_INDEPENDENT_EDGE_MODE | HSPWM_BUFFER_UPDATE_SLAVED_IMMEDIATE |
HSPWM_SINGLE_TRIGGER_MODE | HSPWM_SOC_PWM1_5_PG1_OR_PG5 );
// must force disable all other irrelevant channels, otherwise you cant use shared IO pins
setup_hspwm_unit(3, HSPWM_DISABLE);
setup_hspwm_unit(4, HSPWM_DISABLE);
setup_hspwm_unit(5, HSPWM_DISABLE);
setup_hspwm_unit(6, HSPWM_DISABLE);
setup_hspwm_unit(7, HSPWM_DISABLE);
setup_hspwm_unit(8, HSPWM_DISABLE);
// set duty cycle
set_hspwm_duty(1, duty);
set_hspwm_duty(2, duty);
// set period
set_hspwm_period(1, PwmPeriod);
set_hspwm_period(2, PwmPeriod);
hspwm_update(1);
hspwm_update(2);
// start hspwm module
delay_us(200);
setup_hspwm(HSPWM_CLOCK_AFPLLO | HSPWM_CLOCK_DIV_BY_2, PwmPeriod);
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If it is running, but the phase is not changing with
set_hspwm_trigger_c(1, (unsigned int16)*(0.25*PwmPeriod));
then it sounds as if the second channel is not actually being triggered
correctly.
The second channel needs also to be in single trigger mode.
What are you actually seeing?. |
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SalihLabs
Joined: 27 May 2020
Posts: 8
Location: Ontario, Canada
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| Posted: Wed May 31, 2023 11:37 am |
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Correct, this is only running for the slave.
The AFPLLO is producing 0.5Ghz:
| Code: |
void AFPLLO_settings(void)
{
// can get AFVCO to 1GHz and AFPLLO to 500MHz
// Configure APLL prescaler, both APLL postscalers, and APLL feedback divider
unsigned int8 APOST1DIV = 0;
unsigned int8 APOST2DIV = 0;
#bit APLLEN = getenv("SFR:ACLKCON1").15 // 1 - bypass is disabled, 0 - bypass enabled (bypasses divider output)
#bit APLLCK = getenv("SFR:ACLKCON1").14 // status bit 1 - PLL is in lock 0 - PLL is not in lock
#bit FRCSEL = getenv("SFR:ACLKCON1").8 // FRC clock source select 1 - FRC is the clock source, 0 - Primary Oscillator is the clock source for APLL
#byte APLLPRE = getenv("SFR:ACLKCON1") // APLLPRE[3:0]
#byte APLLFBDIV = getenv("SFR:APLLFBD1") // APLLFBDIV[7:0]
#byte APLLDIV = getenv("SFR:APLLDIV1") // APOST1DIV[6:4] APOST2DIV[2:0]
// AFpllo = Fplli*M/(N1*N2*N3) Fplli = 8 MHz
// AFpllo = 8*125/2 = 500 MHz
FRCSEL = 1;
APLLPRE = 1; // N1 = 1
APLLFBDIV = 125; // M = 125
APOST1DIV = 2; // N2 = 2
APOST2DIV = 1; // N3 = 1
APLLDIV = (APOST1DIV<<4) | APOST2DIV;
APLLEN = 1; // enable APLL
}
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The pwmPeriod is 40,000:
| Code: |
float32 Fosc = 500000000; // 0.5Ghz osc
float32 Fpwm = 100000; // 100khz
unsigned int16 pwmPeriod = (unsigned int16)(8*Fosc/Fpwm); // 40,000
unsigned int16 duty = (unsigned int16)(0.50*pwmPeriod); // 0 to pwmPeriod (0 ... 40000) 4k = 10%, 20k = 50%, 40k = 100%
unsigned int16 deadtime = 60;
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Thank you, it was indeed a problem with the math. I got it to work by fixing set_hspwm_trigger_c(1, (unsigned int16)(5000));
It's always the stupid little problems that are the hardest to troubleshoot.
https://www.youtube.com/watch?v=-TkuMGHYZ4M
Regarding the CCS functions Ttelmah, I cannot find one for setting PG1TRIGC as the PWM generator trigger output under 33CH512MP508S1.h, the closest I can find is SETUP_HSPWM() with parameters HSPWM_ENABLE_TRIGGER_OUTPUT_PWM1_FOR_TRIGGER_A and HSPWM_ENABLE_TRIGGER_OUTPUT_PWM1_FOR_TRIGGER_B (for all PG1 - 8) it is missing for trigger_c, hence why I had to use the SFR.
I also tried to replace HSPWM_RETRIGGERABLE_MODE with HSPWM_SINGLE_TRIGGER_MODE for PG2, it generally works but I noticed PG2 occasionally skips a few cycles. The settings I used are based on the microchip example code I linked. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19536
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| Posted: Mon Jun 05, 2023 10:40 am |
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Just to say, the reason the multiplications didn't work, were an extra
multiplication was in your lines:
PG1TRIGC = (unsigned int16)*(0.125*pwmPeriod);
Needed to be:
PG1TRIGC = (unsigned int16)(0.125*pwmPeriod);
For some reason, you have a * between the cast and the calculated
value. A cast just wants the target type in brackets. No multiplication!... |
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