Update a txt of a form by running the Timer flickering

By code I read the parts that are manufactured and the result I place in the corresponding field of the table. The results of this table I show in a continuous subform and its txt collect the information (control source) of the table that I update every 30 ''. I can't update the txt values ​​if I don't press F5 or use the required method or recalc, but if I use these methods the screen flickers and the Paint property doesn't prevent this flickering. He tried specifically updating the affected txt and writing directly on the txt, but if I don't give F5 it doesn't refresh the subform.