Hi,
I am using 16f676 chip and driving one 7 seg display, what my problem is the vdd is 5v and the rated BOD voltage for this chip is 2.1v which creates dimming effect on 7 seg display. if anybody has any idea to avoid that dimming effect of 7 SEG, would be greatly appreciated.
Prashant
BOD in 16f676 chip
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medelec35
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Re: BOD in 16f676 chip
Hi Prashant,
Are you sure that BOD that's causing the dimming?
if BOD is set to 2.1V ,then for brownout to cause microcontroller to reset then supply voltage has to drop below 2.1V.
If that is occurring then either your circuit is wrong so drawing too much current or power supply is just inadequate for the job.
If your supply going to microcontroller supply pins is not dropping below 2.1V then it's not a BOD issue, but an issue with your flowchart itself.
If you post a circuit diagram and flowchart, I see If I can spot the issue for you.
Martin
Are you sure that BOD that's causing the dimming?
if BOD is set to 2.1V ,then for brownout to cause microcontroller to reset then supply voltage has to drop below 2.1V.
If that is occurring then either your circuit is wrong so drawing too much current or power supply is just inadequate for the job.
If your supply going to microcontroller supply pins is not dropping below 2.1V then it's not a BOD issue, but an issue with your flowchart itself.
If you post a circuit diagram and flowchart, I see If I can spot the issue for you.
Martin
Martin
Re: BOD in 16f676 chip
Hi Martin,
first of thanks for the reply, secondly excuse me for the incomplete description of my problem,
i have connected a 1000uF bulk cap across supply. BOD threshold for 16F676 is 2.1V, and the same for 16F628A is around ~4.2V, earlier i did not mention that on power down Display with 16f628A turns off immediately(when 5v drops to 4.2v device resets and supply never comes up so off). on the other hand on power down display with 16f676 goes off slowly (because it takes time to drop supply from 5v to 2.1v ), till then system is operating normally but as power is getting down so LEDs of display goes dim
Prashant
first of thanks for the reply, secondly excuse me for the incomplete description of my problem,
i have connected a 1000uF bulk cap across supply. BOD threshold for 16F676 is 2.1V, and the same for 16F628A is around ~4.2V, earlier i did not mention that on power down Display with 16f628A turns off immediately(when 5v drops to 4.2v device resets and supply never comes up so off). on the other hand on power down display with 16f676 goes off slowly (because it takes time to drop supply from 5v to 2.1v ), till then system is operating normally but as power is getting down so LEDs of display goes dim
... yess Martin this the case, in short on manual power down display should go off immediately like 16f628a systemif BOD is set to 2.1V ,then for brownout to cause microcontroller to reset then supply voltage has to drop below 2.1V.
Prashant
Re: BOD in 16f676 chip
Hi all,
got workaround for this... which is suggested by Ben.
measuring VDD on ine anlogue input and if that input is less than the full count then reset the micon..
thanks Ben for that
got workaround for this... which is suggested by Ben.
measuring VDD on ine anlogue input and if that input is less than the full count then reset the micon..
thanks Ben for that