[Moved] Readout cycles off and on

[bluejets]

Downloaded this project for digital tacho driving 4 x 7 led display.
It works ok as far as tracking the revs but the display blanks out for a few seconds and then it displays for the same period and then turns off again repeatedly.
Is the problem somewhere in the "delay" in the sampling section..??

https://pic16f628a.blogspot.com.au/2010/10/contact-less-tachometer.html

 

[bigdogguru]

It works ok as far as tracking the revs but the display blanks out for a few seconds and then it displays for the same period and then turns off again repeatedly.
Is the problem somewhere in the "delay" in the sampling section..??

Yes, most likely the issue with display is due to the over use of software generated delays.

As a general rule software delay routines should be avoided, except perhaps during device initialization, e.g. LCD, GLCD, etc.

Even during these device initialization phases, the software generated delays should be kept to a minimum, 150ms or less.

In the case of stated example code, a much more prudent method of implementation would be the utilization of interrupts, rather than software generated delays.

One of the main issues with software delay routines is they essential suspend code execution during the entire delay interval, in a sense locking up microcontroller for the duration of the delay.

An interrupt combined with an interrupt service routine (ISR), on the other hand, allows the microcontroller to perform other tasks until an interrupt occurs at which point the code exection flow switches to the task defined within the ISR.

As many seven segment implementation rely on refresh multiplexing to effectively update and refresh each of the seven segment displays, software delay routines can obviously impede the required refresh multiplexing routines.

BigDog