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Altera_Forum
Honored Contributor I
815 Views

CVI overflow and CVO underflow

Hi, 

 

CVI(run control) -- CVO(run control) , 

 

cvi always overflow,cvo always underflow. why? How to set the fifo depth? 

 

 

nios config code is as follows, 

 

 

/**************************** CTI **************************************/ 

printf("/*******************************************\n"); 

printf("CTI_control is %x!\n",CTI->control ); 

printf("CTI_STATUS is %x!\n",CTI->status ); 

printf("\n"); 

 

 

// 

// updata control data 

// 

CTI->control = 0x0006; 

 

 

// 

// set go bit 1 

// 

CTI->control = CTI->control | 0x0001; 

 

 

 

printf("After config.\n"); 

printf("CTI_control is %x!\n",CTI->control ); 

printf("CTI_STATUS is %x!\n",CTI->status ); 

printf("\n"); 

 

 

 

 

// /************************** ITC ****************************************/ 

 

printf("/*******************************************\n"); 

// 

// mode1 HD 

 

 

// disable mode1_valid 

ITC->mode1_valid = 0; 

// set mode1 registers 

ITC->mode1_control = 1; 

ITC->mode1_sample_count = 1920; 

ITC->mode1_f0_line_count = 540; 

ITC->mode1_f1_line_count = 540; 

ITC->mode1_hfront_porch = 0; 

ITC->mode1_hsyn_length = 0; 

ITC->mode1_h_blanking = 720; 

ITC->mode1_vfront_porch = 0; 

ITC->mode1_vsync_length = 0; 

ITC->mode1_v_blanking = 22; 

ITC->mode1_f0_vfront_porch = 0; 

ITC->mode1_f0_vsync_length = 0; 

ITC->mode1_f0_v_blanking = 23; 

ITC->mode1_active_picture_line = 21; 

ITC->mode1_f0_v_rising = 561; 

ITC->mode1_field_rising = 564; 

ITC->mode1_field_falling = 1; 

ITC->mode1_std = 0; 

// ITC->mode1_sof_sample; 

// ITC->mode1_sof_line; 

// ITC->mode1_vcoclk_div; 

ITC->mode1_ancillary_line = 9; 

ITC->mode1_f0_ancillary_line = 571; 

 

 

// enable mode1_valid 

ITC->mode1_valid = 1; 

 

 

// 

// mode2 SD 

 

 

// disbale mode1_valid 

ITC->mode2_valid = 0; 

 

 

// set mode1 registers 

ITC->mode2_control = 3; 

ITC->mode2_sample_count = 720; 

ITC->mode2_f0_line_count = 288; 

ITC->mode2_f1_line_count = 288; 

ITC->mode2_hfront_porch = 0; 

ITC->mode2_hsyn_length = 0; 

ITC->mode2_h_blanking = 144; 

ITC->mode2_vfront_porch = 0; 

ITC->mode2_vsync_length = 0; 

ITC->mode2_v_blanking = 24; 

ITC->mode2_f0_vfront_porch = 0; 

ITC->mode2_f0_vsync_length = 0; 

ITC->mode2_f0_v_blanking = 25; 

ITC->mode2_active_picture_line = 23; 

ITC->mode2_f0_v_rising = 311; 

ITC->mode2_field_rising = 313; 

ITC->mode2_field_falling = 1; 

ITC->mode2_std = 0; 

// ITC->mode2_sof_sample; 

// ITC->mode2_sof_line; 

// ITC->mode2_vcoclk_div; 

ITC->mode2_ancillary_line = 8; 

ITC->mode2_f0_ancillary_line = 321; 

 

 

// enable mode2_valid 

ITC->mode2_valid = 1; 

 

 

printf("ITC control is %x!\n",ITC->control ); 

printf("ITC status is %x!\n",ITC->status ); 

 

 

// enbale control, cvo output data 

ITC->control = 0x1e; 

ITC->control = ITC->control | 0x01;
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1 Reply
Altera_Forum
Honored Contributor I
79 Views

Hi,  

 

This is normal that the CVI overflow or CVO underflow if without a frame buffer at between.  

 

In the real system this is suggested to have a frame buffer: CVI-> FB -> CVO.  

 

 

Best Regards, 

Terence 

 

(This message was posted on behalf of Intel Corporation)
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