Dear,
I combined the TLC5940 with my MCU (nuvoton NUC123) trying to control servo motor; however, there are some problems in the duty of PWM signal. I can’t adjust the right duty even the trend seemed correct. I did not use the dot correction but just gray scale.
Figure 1
Take these two pictures for example, the first is the timing diagram of my SPI command, BLANK, and XLAT. I set 10 in SPI packet, that should mean the low level maintain 10 GSCLK and then PWM transfers to high level, am I right?
Fig.2
But the red frame of the Fig.2 shows that it not only 10 CLK but about 80 CLK during low level. This will cause the fault outcome.
I have done some tests trying to find how could this happen.
1. I change the frequency of GSCLK, this problem still goes and with the higher frequency the number of clock during low level grows.
2. I change the timing of falling edge of BLANK and XLAT pulse, there is no use.
I can’t understand why, the PWM “seems” work, however the outcome has problem. Please give me some instructions! Thanks a lot!
Maxwell
