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Updating TLC5940 Dot Correction

Samuel Loho
Prodigy 30 points
Other Parts Discussed in Thread: TLC5940

Hi,

I am working on a project involving TLC5940 chip and i have a question regarding the dot correction mode on the chip.

I am aware that the dot correction register must be set at the power up if I were to use the dot correction value stored on the register. Is it possible to update the register not on the start up?

At the moment Im connecting the chip with Atmel ATmega 8 and using USART to communicate with the chip. I am able to change the Greyscale value using a set of USART interrupt command but no success in changing the dot correction value using the same method.

My code on changing the DC value is as follow: set an array that holds the value for all 16 channel (96 bits) and clock in the DC value by transmit the value using SPI register and pulsing XLAT after it finished transmitting. This is the same steps that I have used for setting the DC value at the power up, but fail at changing the value by using USART command. Therefore, If the value for dot correction register need to be changed using the same method (i.e. set of USART command via interrupt), can anyone point me to the right direction on how to do so?

 

Thanks

  • 0
    TI__Mastermind 36110 points

    You can change the TLC5940 (and all other TLC59xx products with dot correction build to date) at any time.  The conditions for changing dot correction at power up are the same as changing dot correction at any other time.  Figure 15 shows the correct sequence.  You should look in detail at the timing of your circuit to find out what is different between your first change of dot correction values and later changes.  There must be a difference between the two.  Also be sure to double check all the setup and hold times.