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DMA trigger by TIM1 Conifguration -PWM generation not getting correct PWM

thannara123
Senior

I am generating PWM signals for 4 channels using TIM1, with 2 complimentary outputs. The CCR values should come from an array lookup table via DMA.

 

Screenshot 2024-05-02 at 10.43.06 AM.pngis this means The DMA trigger by TM1 ?

 

Screenshot 2024-05-02 at 10.45.16 AM.png

 

 

 

I am trying to generate a sinewave from the following array 

uint16_t sin_table[160]={0, 5, 10, 15, 20, 25, 29, 34, 39, 44, 49, 54, 58, 63, 68,

73, 77, 82, 87, 91, 96, 100, 105, 109, 113, 118, 122, 126, 131, 135, 139,

143, 147, 151, 155, 159, 162, 166, 170, 173, 177, 180, 184, 187, 190, 193,

196, 199, 202, 205, 208, 211, 213, 216, 218, 220, 223, 225, 227, 229, 231,

233, 235, 236, 238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 248, 249,

249, 250, 250, 250, 250, 250, 250, 250, 249, 249, 248, 248, 247, 246, 245,

244, 243, 242, 241, 239, 238, 236, 235, 233, 231, 229, 227, 225, 223, 220,

218, 216, 213, 211, 208, 205, 202, 199, 196, 193, 190, 187, 184, 180, 177,

173, 170, 166, 162, 159, 155, 151, 147, 143, 139, 135, 131, 126, 122, 118,

113, 109, 105, 100, 96, 91, 87, 82, 77, 73, 68, 63, 58, 54, 49, 44, 39, 34, 29, 25, 20, 15, 10, 5};

 

HAL_TIM_PWM_Start_DMA(&htim1, TIM_CHANNEL_1, (uint32_t *)sin_table, 160);

HAL_TIMEx_PWMN_Start_IT(&htim1, TIM_CHANNEL_1);

HAL_TIM_PWM_Start_DMA(&htim1, TIM_CHANNEL_2, (uint32_t *)sin_table, 160);

HAL_TIMEx_PWMN_Start_IT(&htim1, TIM_CHANNEL_2);

I am not getting the 160 values as per the array value 

FPWM is 16KHZ

Screenshot 2024-05-02 at 10.56.11 AM.pngWhat wrong with me ?

please help me

@AScha.3 

16 REPLIES 16

Center aligned mode counts up and down - so double time (62 -> 124 us ) , as "normal" pwm mode.

 

AScha3_0-1714657555576.png

 

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thannara123
Senior

Thanks

If I require an FPWM frequency of 16 kHz, I need to set the ARR value to generate 8 kHz, isn't it?"

If PWM frequency of 16 kHz should come out, with center al.mode , ARR <- value for 32 kHz .

Just try it, nothing will explode...if you set something wrong. :)

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thannara123
Senior

Also when I select center align Mode 1 ,there is no output is getting.

it works if i select Centre algin mode 2 

why so ?

I am not sure (i never tried) - see description , as i posted.

But i would try mode 3 - tell, what comes out. Because mode 3 (as i understand description) is true center mode, ccr compare on rising + falling counter. Mode 2 only on rising...

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@thannara123,

Why do you insist on using center-aligned mode?

JW

thannara123
Senior

Center aligned not a compulsory ,But I heared it has some benifit over old PWM ,like reduced EMI ,Improved efficiency,Enhanced resolution and accuracy.. I donnt know how is that .

 

 I am doing projects for learning purpose right now .