Bug in my timekeeping code

[Dave]

I also see the same mistake in the 24 hour mode where you say if hour = 25 then hour = 1. 24 hour time starts from 00:00 to 23:59.

BTW, Nice PCB. I have some RCA Numitrons with 9 pin sockets. I was thinking about using them for a clock but the lifetime of the tubes isn't very good so I built a couple of nixie clocks with VM1000 tubes. Attacked is a photo.

Dave Purola,

[Amoque]

I am wondering if it would be easier to keep only a TotalElapsedSeconds count and calculate HRS, MNS, and SDS as needed? I admit that I have not tried this, but it seems feasible. A word variable easily holds 13 hours (in seconds) and AM/PM or 24 hour clock flag provides convenient flags to indicate the 12 hour adjustment needed to avoid rollover (subtract 43200 at 46800). so:

Just a little while after midnight (when the counter and flag resets to zero), TotalElapsedSeconds might be, say... 1146. In that case,

HRS= 1146/ 3600 = 0
MNS= 1146 - (HRS * 3600) / 60 = 19
SCS= 1146- (HRS * 3600) - (MN * 60) = 06 - the time 00:19:06, is correct.

Closer to noon, the total might be 43321.
HRS= (43321/ 3600) = 12
MNS= 43321- (HRS * 3600) / 60 = 02
SCS= 43321- (HRS * 3600) - (MN * 60) = 01 - the time 12:02:01, is correct.

At 1:00, the timer would be 46800 and subtracting 12 hours (43200 seconds) leaves TotalElapsedSeconds = 3600, or exactly 1:00:00 (or by adding 12, 13:00 in 24H mode). The caveat here is that the midnight adjustment and the 1:PM adjustment are not symmetric at 12 hours each - something of a kludge or, perhaps the time as 24:00:01 is of no issue to you? If not, then the time may rollover to 1:00:00 in even 12 hour cycles.

To set the time, adding or subtracting 3600 adjusts the time by an hour, similarly adding or subtracting 60 changes the time a minute.

I have considered this approach as a means of simplifying clock adjustments - say a user wants to subtract 10 minutes at only 5 minutes past the hour - in this way (I think) it may be simpler than fiddling with decrementing the hour separately.

[astouffer]

I also see the same mistake in the 24 hour mode where you say if hour = 25 then hour = 1. 24 hour time starts from 00:00 to 23:59.

BTW, Nice PCB. I have some RCA Numitrons with 9 pin sockets. I was thinking about using them for a clock but the lifetime of the tubes isn't very good so I built a couple of nixie clocks with VM1000 tubes. Attacked is a photo.

Dave Purola,

Dave, nice looking clock as well. The boards came from a place called OSH Park. They run batches of boards so the average time is about two weeks but the quality and price is great. Purple boards seem to be their trademark. If you are worried about longevity of the numitrons you can use the TLC5916 or similar chips from TI. They are meant for driving LEDs and have an adjustable constant current feature. For some reason the minute digits were both dimmer than the hours and needed slightly different resistor values.

[astouffer]

Forgive my ignorance but I can not see why during the timekeep loop that the minutes increment to 01 if they are set to 00 from the previous loop

timekeep:							
ss = ss + 1							
if ss = 60 then
	ss = 0 
 	mm = mm + 1
endif
if mm = 60 then 
	mm = 0
	hh = hh + 1
endif
if hh = 13 then hh = 1				
v1 = hh DIG 1
v2 = hh DIG 0

v3 = mm DIG 1
v4 = mm DIG 0

if hh < 10 then
lookup v1, [$00,$60,$57,$76,$6C,$3E,$3F,$70,$7F,$7E], v1
else
lookup v1, [$7B,$60,$57,$76,$6C,$3E,$3F,$70,$7F,$7E], v1
endif

lookup v2, [$7B,$60,$57,$76,$6C,$3E,$3F,$70,$7F,$7E], v2
lookup v3, [$7B,$60,$57,$76,$6C,$3E,$3F,$70,$7F,$7E], v3
lookup v4, [$7B,$60,$57,$76,$6C,$3E,$3F,$70,$7F,$7E], v4

shiftout dat, clk, 0, [v2, v1]
pulsout hstro, 10
shiftout dat, clk, 0, [v4, v3]
pulsout mstro, 10

INTCON.2 = 0						'Clear interrupt flag
resume startloop					'Go back to the do nothing loop

Looking at this statement

ss = ss + 1							
if ss = 60 then
	ss = 0 
 	mm = mm + 1
endif

The minutes should be at 00 until 60 seconds have been counted. Why is it jumping to 01 instead?

[Amoque]

The only other place I see you modifying the mm value is in the "setmm:" routine. You do not say if you are setting the clock (where the code in your OP sets mm = 1) or not.