Is it possible to control the TLC5940 with only 3 mpu pins?
I can probably get along with GS without the DC.
To be honest, I never tested it, but I do not think so. You need SIN and SCLK for data to be clocked into the IC. You need GSCLK to turn on and off the outputs and you need XLAT to latch the new data into the GS registers. In addition, I do not think that this will work without having the BLANK signal.
Maybe you will be able to find a part in our LED driver portfolio which still matches your requirements and has another interface. We have 2 16 channel drivers that are using I2C, for example. Please have a look onto the LED drivers web page
I already have it wired up to 4 micro pins as follows
Micro connected to SIN, SCLK, XLAT and GSCLK.
BLANK wired low. VPRG wired low. DCPRG wired high. IREF wired though 7.812k to ground.
My GSCLK runs at 32khz.
I initialize by shifting 193 bits in to overflow the input shift register and then latching as
described on page 17..
Then I shift in 192 GS bits every 125 ms to set the GS.
But so far, no led output? Should this work?
Thanks for the LED driver web page link. It looks like the TLC9571 is just what I need
since it has 16 bit GS, more than enough output channels, and only 2 micro pins required.
However, it is a new part that is not stocked anywhere. If I put this in my new design,
how long before I can get parts from distributors?
In the datasheet on page 19 you can find a description of the grayscale PWM operation. The following sentence is the first one: "The grayscale PWM cycle starts with the falling edge of BLANK." A falling edge on BLANK starts the GS cycle, therefore you should not pull BLANK completely to GND. This means you need another output of the microcontroller, sorry.
Please ask your distributor about the time when you can get TLC5971.
Can I connect the VPRG and BLANK pins and drive them from 1 of my micro pins?
I would like to use DC but I am low on micro pins.
Yes, you can connect VPRG and BLANK together. Please note that you can not shift in any grayscale data into the IC when VPRG and BLANK are pulled high because the TLC5940 will put the data into the Dot Correction Register. Also note that you must program the dot correction register after power up and prior to displaying data because all internal registers are undefined after power on.
All content and materials on this site are provided "as is". TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with regard to these materials, including but not limited to all implied warranties and conditions of merchantability, fitness for a particular purpose, title and non-infringement of any third party intellectual property right. TI and its respective suppliers and providers of content make no representations about the suitability of these materials for any purpose and disclaim all warranties and conditions with respect to these materials. No license, either express or implied, by estoppel or otherwise, is granted by TI. Use of the information on this site may require a license from a third party, or a license from TI.
TI is a global semiconductor design and manufacturing company. Innovate with 100,000+ analog ICs andembedded processors, along with software, tools and the industry’s largest sales/support staff.