TLC5940 question

I've read through the datasheet of the 5940 and i think i have a better understanding
of how it works.

I have a question before i start to bitbang it.

Can i continously run a clock to GSCLK pin and toggle the BLANK pin after 4096 clocks
from within an ISR , while updating Greyscale data asynchronous in a main function to update the the channels with new PWM data?

Sure can.

I use an actual PWM output for the 4096 clocks and count them with a counter input. Then an ISR fires after counting 4096 clocks from the PWM output.

Can i update the GS registers while in the middle of a GSclock signal between 0 and 4096 ?

Are there any drawbacks for doing this?

Yes that is fine. No drawbacks. The chip is designed for this purpose.

The GreyScale data is not actually latched in to the internal registers until the XLAT (latch) pulse.