Hi Here is my pseduo-code:
// In my CAPCOM1 initalisation CC1_T0REL=0xF830; // Generate 10kHz PWM // Produce 50% duty cycle Offset=(0xFFFF-CC1_T0REL)>>1; // This will produce 50% duty cycle of 10kHz PWM CC1_CC2=CC1_T0REL+Offset;
I don't mind helping you but I don't think you have understood what I said so far about how the CAPCOM works. Anyway, here is an example of what you asked for. Please look at the code and see if you understand it...
void main(void) { CC1_IOC = 0x0004; CC1_T0 = 0xEC78; CC1_T0REL = 0xEC78; CC1_T01CON = 0x0001; CC1_M0 = 0x5500; CC1_M1 = 0x0005; offset1 = ((0xFFFF - CC1_T0REL)/3); offset2 = ((0xFFFF - CC1_T0REL)/3)*2; CC1_CC2 = 0xEC78; CC1_CC3 = CC1_T0REL + offset2; CC1_CC4 = CC1_T0REL + offset1; _bfld_(ALTSEL0P6,0x001C,0x001C); _bfld_(DP6, 0x001C, 0x001C); CC1_OUT = 0x0014; CC1_T01CON_T0R = 1; PSW_IEN = 1; for(;;) { } }
I have been using processor for few months and I am still learning more about it everyday. :-) Here is my comments:
void main(void) { // It runs non staggered mode & Assign Compare output signals affect the associated output CC1_IOC = 0x0004; // Start the timer (4kHz) CC1_T0 = 0xEC78; // Reload Register (60536) It counts upward CC1_T0REL = 0xEC78; // T0l is 001 hence prescaler is 16 and frequency is 2.5MHz CC1_T01CON = 0x0001; // Assign to TO and run compare mode 1 CC1_M0 = 0x5500; // Assign to TO and run compare mode 1 CC1_M1 = 0x0005; // These are used to work out for Phase B & C offset1 = ((0xFFFF - CC1_T0REL)/3); offset2 = ((0xFFFF - CC1_T0REL)/3)*2; // 0 degree - Phase A CC1_CC2 = 0xEC78; // 120 degree hence Phase B CC1_CC3 = CC1_T0REL + offset2; // 240 degree hence Phase C CC1_CC4 = CC1_T0REL + offset1; // Set the CC1_CC2/CC1_CC3 and CC1_CC4 output and set them high _bfld_(ALTSEL0P6,0x001C,0x001C); _bfld_(DP6, 0x001C, 0x001C); // Hmmm not sure about that... // It is do with Compare output signal generation // But i presume it generates signal on // CC410 and CC210. What about CC310? CC1_OUT = 0x0014; // Enable Interrupt for Timer 0 CC1_T01CON_T0R = 1; // Enable global interrupt?? PSW_IEN = 1; // Run forever for(;;) { } }
Great, I am happy that you are learning. So I will gently correct some issues… Compare mode 1 will toggle the respective output pin on every compare match with the allocated timer. It also allows several compare events within a single timer period. An overflow of the allocated timer has no effect on the output signal, nor does it disable or enable further compare events. You asked for a 2-KHz PWM signal at 50% duty cycle so this is why the CC1_T0REL (Timer 0 reload register) is set to 0xEC78. You need a transition at the pin every 250usec; 0x10000 – (250usec / 50nsec) = 0xEC78.
CC1_T0 = 0xEC78; /*initial (starting) value for T0 */ CC1_T0REL = 0xEC78; /* reload value for T0 which is reloaded upon a overflow of T0*/ _bfld_(ALTSEL0P6, 0x001C,0x001C); /* use alternate outputs for P6.2, P6.3 and P6.4*/ _bfld_(DP6, 0x001C, 0x001C); /* configure pins P6.2, P6.3 and P6.4 as outputs*/ CC1_OUT = 0x0014; /*set initial value of the pins P6.2 and P6.4 high (phases A and C)*/ CC1_T01CON_T0R = 1; /* set the run bit of T0, counter is now running */
Dear Chris Thank you for pointing out my mistakes. Instead of using a 50% fixed duty cycle, is it possible to vary duty cycle while implementing compare mode 1 in a timer (let say 0) interrupt? Because in my previous project, I managed to generate sine wave using compare mode 3 such as phase_1=sine[index]*amplitudecontrol // 0 degree phase_2=sine[index+33]*amplitudecontrol // 120 degree phase_3=sine[index+66]*amplitudecontrol // 240 degree This carries out in timer 0 ... I am aware that you mentioned earlier that I should add the value to the compare register the next toggle event within the ISR. Also I have seen the codes but the problem is that I cannot use PEC or Double regsiter because it will limits to 8 channels as I need to use 12 channels. So this is what I think I should do is to generate an array of sine wave values and in ISR routine, the data is increment which add to the compare register for next toggle?
#include <XC161.h> #include <intrins.h> int offset1, offset2; int Duty_Cycle; void main(void) { CC1_IOC = 0x0004; CC1_T0 = 0xEC78; // inital value of T0 CC1_T0REL = 0xEC78; // Reload value for T0 which is loaded upon an overflow of TO CC1_T01CON = 0x0001; // Prescaler - 16, (001) hence 2^1 CC1_M0 = 0x5500; CC1_M1 = 0x0005; offset1 =((0xFFFF - CC1_T0REL)/3); offset2 =((0xFFFF - CC1_T0REL)/3)*2; CC1_CC2 = 0xD8F0; CC1_CC3 = CC1_T0REL + offset2; CC1_CC4 = CC1_T0REL + offset1; _bfld_(ALTSEL0P6, 0x001C, 0x001C); _bfld_(DP6, 0x001C, 0x001C); CC1_OUT = 0x0014; CC1_CC2IC = 0x007c; //Enable interrupt, GROUP 0, ILVL - 15 CC1_CC3IC = 0x007E; //Enable interrupt, GROUP 0, ILVL - 14 CC1_CC4IC = 0x007D; //Enable interrupt, GROUP 0, ILVL - 13 CC1_T01CON_T0R=1; PSW_IEN=1; for(;;) { } } void CC1_viCC2(void) interrupt 0X12 { index++; if(index==100) { index=0; } CC1_CC2=(sine[index]+T0REL); } void CC1_viCC3(void) interrupt 0X13 { index2++; if(index2==100) { index2=0; } CC1_CC3=(sine[index2]+T0REL); } void CC1_viCC4(void) interrupt 0X14 { index3++; if(index3==100) { index3=0; } CC1_CC4=(sine[index3]+T0REL); }
Here is my latest work.... Instead of using void CC1_viCC2(void), void CC1_viCC3(void) and void CC1_viCC4(void). I use the Timer 0 for change duty cycle and it works but it not producing a proper sine wave as it is distorted. why is that? Here is my pseduo code: CC1_viTimer0(void) { index++; if(index==128) { index=0; } // these are designed to produce sinewave CC1_CC2=sinewave[index]*amplitude CC1_CC3=sinewave[index]*amplitude CC1_CC4=sinewave[index]*amplitude } Let you know I use 2kHz/128 (array of sine wave value) which generates 15Hz.... It seems that I am doing summat wrong at the moment. Could not solve this problem at the moment. I would appreicate to hear from you asap Kind regards AJ
What should I do? I don't believe I have enough of your code to produce the problem? What is the value and type of amplitude? What are the values and type for the sinewave? You need to provide a code snippet that I can run...
Dear Chris RECAP: You demonstrated me to implement 2kHz at fixed 50% DC starting at 0 degree, 120 degree and 240 degree respectively. Then I need to vary duty cycle rather than fixed as I need to produce sine waveform.... Here is my more codes... Bascially what I tried to produce three sine wave at 0 degre, 120 degree and 240 degree respectively hence varying duty cycle at CC1_CC2, CC1_CC3 and CC1_CC4 respectively. So far I only get a look-like triangular waveform. Is it possible to implement it without the use of PEC and Double-register?
#define DEGREE 2.8125 #define NUMBER_POINT 213 #define TABLE_SIZE 128 //Global variables unsigned int SineWave[TABLE_SIZE]; int offset, Duty_cycle,index,pwm_ref; Duty_Cycle=(0xFFFF - 0xEC78)>>1; for (index=0; index<NUMBER_POINT; index++) { SineWave[index]=(Duty_Cycle*sin(((index*DEGREE)*3.14159)/180)); } void main(void) { CC1_IOC = 0x0004; // Non-staggered mode CC1_T0 = 0xEC78; // inital value of T0 CC1_T0REL = 0xEC78; // Reload value for T0 which is loaded upon an overflow of TO CC1_T01CON = 0x0001; // Prescaler - 16, (001) hence 2^1 CC1_M0 = 0x5500; // S CC1_M1 = 0x0005; offset1 =((0xFFFF - CC1_T0REL)/3); offset2 =((0xFFFF - CC1_T0REL)/3)*2; CC1_CC2 = 0xEC78; CC1_CC3 = CC1_T0REL + offset2; CC1_CC4 = CC1_T0REL + offset1; _bfld_(ALTSEL0P6, 0x001C, 0x001C); _bfld_(DP6, 0x001C, 0x001C); CC1_OUT = 0x0014; CC1_T01CON_T0R=1; PSW_IEN=1; for(;;) { } } void CC1_viTmr0(void) interrupt CC1_T0INT { int Phase_Int; long int TempLong,Phase_LongInt; // increment the position of the sine wave table pwm_ref++; // if at the end of the look up table then restart if(pwm_ref >= 128) { pwm_ref = 0; } TempLong = 1.0 * 10000; // save amplitude as a long Phase_LongInt = SineWave[pwm_ref]*TempLong; Phase_Int=Phase_LongInt/10000; CC1_CC2=Phase_Int+CC1_T0REL; // Produce sine wave for phase A CC1_CC3=Phase_Int+CC1_T0REL; // Produce sine wave for phase B CC1_CC4=Phase_Int+CC1_T0REL; // Produce sine wave for phase C }
Can I ask what are controlling? You said you need to create 12 channels so are you controlling 4 motors? Or 2 and you need complementary channels (6 channels per motor)? Are you using an external three phase driver that also generates the dead-time? Can you use edge aligned PWM's or do they need to be center aligned? Did you say you are using an XC167? You know this has 2 CAPCOM timer units and 1 CAPCOM6 timer unit. The CAPCOM6 was specifically designed for three phase motor control. Ok, I see a couple of issues with the code. First you have are exceeding your SineWave array (128 entries) by NUMBER_POINT (213). You need TABLE_SIZE to be equal or less than the TABLE_SIZE. When creating the sine table you need to add an offset so the sine wave is all positive values (in your example 2500). Since you want to vary the duty cycle and given your other criteria then I would recommend to switch to compare mode three. Compare Mode 3 will only have one event per timer period and the when you have a compare event the signal is set and on the timer event the signal is reset. When writing a new compare value after the event it will only be valid after the next timer period. Note the PWM's would be edge aligned, is this ok? In the timer interrupt service routine you need to manage three different indexes (or three sine tables which represent 120 degree phase shifts). Are you familiar application note Ap0802211_3-Phase-Currents.pdf on the Infineon website?
Dear Chris Yes, the aim is to control 4 motors using 12 channels. I use hardware to generate non-inverted and inverted PWM to drive a motor so we don't implement dead-time. Unfortunately I am working on the XC161 chip at this stage and so I cannot choose different family. However I try to switch XC167 in the future project For the sine-wave array, the reason I use 213 arrays because my algorithm allows 3 different phases point at different points. For example, Phase A start at 0, Phase B and C point at 43 and 85 respectively. Phase A: 0 to 360 degree which correspond to 0 to 128 Phase B: 0 to 360 degree which correspond to 43 to 171 Phase C : 0 to 360 degree which correspond to 85 to 213 I have written a code to produce 3 sine waveforms by using CAPCOM1's compare mode 3 instead of 1 and 3. I managed to produce Phase A and B in 120 phase shift. I recently found that I could not use the CAPCOM2 for timer 7/8 because the pins are allocated for something else! This forces me to use the General Purpose Timer 1's Timer block 2 and 3 for generating sine wave. Today has been terrible for me and I have not used it before and I know it works in similar principle like CAPCOM but I could not quite manage it. You see I selected timer 2 counting downward and enable interrupt for updating the value of T2 in order to produce sine wave. But nothing happens…… AJ
Btw can we keep in touch by email? AJ
You can reach me at chris.wunderlich(at)infineon.com
Im going to keep your email address in my notebook. After reading the datasheet regarding General Purpose Timer 1 epsecially implementing PWM. I have noticed that it needs three Timer blocks for producing each tick and pulse width for high and low. I know that T3 can be used to control Pin 3. The question is that is it possible to implement GPT1 with one timer block and toggle any port? AJ
Yes, you can just use T3 to toggle pin P3.3 (T3OUT). Here is an example that uses the PEC to reload T3 (but only a 50% DC). If you want to use software then you can change the duty cycle for T3 and also use T2 and T4. However you would need to modify a port pin within the interrupt (meaning you would have to deal with the interrupt latency).
unsigned int T3reload; void main(void) { /* timer 3 works in timer mode prescaler factor is 8 timer counts down alternate output function T3OUT (P3.3) is enabled timer 3 output toggle latch (T3OTL) is set to 1 */ GPT12E_T3CON = 0x0680; T3reload = 0x04E1; /* 2KHz, 50% DC */ GPT12E_T3 = T3reload; /* P3.3 is used for Timer 3 Toggle Output (T3OUT) */ _bfld_(ALTSEL0P3,0x0008,0x0008); /* select alternate output */ _bfld_(P3,0x0008,0x0008); /* set data register */ _bfld_(DP3,0x0008,0x0008); /* set direction register */ /* PEC0:(ILVL) = 14, (GLVL) = 0, (GPX) = 0 */ GPT12E_T3IC = 0x0078; PECC0 = 0x00FF; /* continuous transfer */ SRCP0 = _sof_ (&T3reload); /* source pointer */ DSTP0 = _sof_(&GPT12E_T3); /* destination pointer */ GPT12E_T3CON_T3R = 1; /* set timer 3 run bit */ PSW_IEN = 1; for(;;) { } }
Thank you for illustrating another example of using General Purpose Timer 1. It seems that 3 timer blocks are need to produce PWM especially varying duty cycle. Thank you for letting me know. Kind regards AJ