show graphic can't keep (IDFGH-14236)

[learnerzcz]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

i use spi master demo in lcd display, the displayed "esp32" only keep a moment, how can i keep it displaying

` while (1) {
// frame++;
for (int y = 0; y < 240; y += PARALLEL_LINES) {
// printf("y=%d\n",y);
//Calculate a line.
pretty_effect_calc_lines(lines[calc_line], y, frame, PARALLEL_LINES);
//Finish up the sending process of the previous line, if any
if (sending_line != -1) {
send_line_finish(spi);
}
//Swap sending_line and calc_line
sending_line = calc_line;
calc_line = (calc_line == 1) ? 0 : 1;
//Send the line we currently calculated.
send_lines(spi, y, lines[sending_line]);
//The line set is queued up for sending now; the actual sending happens in the
//background. We can go on to calculate the next line set as long as we do not
//touch line[sending_line]; the SPI sending process is still reading from that.
}
// vTaskDelay(pdMS_TO_TICKS(100));

 }`

[nopnop2002]

how can i keep it displaying

If you do not change any of the code provided as an example, it will continue to display.
Note that the sample code shifts the displayed data in small increments.

[learnerzcz]

Yes，i found the problem ,is the backlight level is err i set.