stm32f429 etm trace

[alireza_roozitalab]

Posted on January 23, 2016 at 14:24

hello i want to use 4pin etm trace (ukink pro )on stm32f429

and i have this problem:

if  core clock > 100 mhz i cant use etm trace

and if core clock<140 mhz i cant use ltdc

is there any true configs for use etm trace on 180 mhz ?

or how can i use ltdc  in core clock <140 mhz?

best regards

[re.wolff9]

Posted on January 24, 2016 at 10:09

I had to look up what LTDC is. It's a TFT interface. 

In my experience LCD will work at lower clocks than nominal. If something claims it won't work below 140MHz, you might ''cheat'' and e.g. tell everything that you have a 16MHz external crystal while in fact you have a 8MHz one. Now the CPU will run at 90MHz, the LCD will refresh at 30Hz instead of 60Hz, but  maybe the ETM might work.... 

[alireza_roozitalab]

Posted on January 24, 2016 at 12:45

first of all thanks for your replay

yes  I use tft lcd 8 inch (480*800 pixel) in RGB888 mode

and my sdram is k4s561632c

board crystal is 8mhz

i self designed board with stm32f429IIT

and have not any problem with ltdc peripherals(tft lcd) if core clock>140mhz .

i check sdram by writing and reading value and check them in core clock lower than 140 mhz and i seen that every ting work correctly

and i use const picture in flash of micro to show on lcd  (without using sdram) and i seen that it work true on core clock <140mhz !!!!!!!

 but i cant used sdram and ltdc with each other in core clock <140 mhz  , the lcd show is unclear

best regards