Hello,
I'm considering my approach to a new appliance controller I want to put together.
The controller is responsible for receiving user inputs, listening to a sensor, and sending a signal to a peripheral actuator (as well as an LCD display).
I've built a controller that does the above tasks, but now want to build an "enhanced" version that includes a clock/timer (in the traditional sense of human timekeeping).
Some configurations I've considered:
#1
I have a feeling that I could do a mediocre to poor job using my MCU internal oscillator with timer driven interrupts that are appropriately prioritized to track time. I think this is fairly poor due to the fact that at times global interrupts will be disabled, and also because temperature and other factors will influence the speed of the internal oscillator.
#2
A slight improvement to #1 might be able to be made by using the same general approach as #1, but driving the MCU (or just TIMER0) with a more accurate external oscillator.
#3
I could shell out for an additional RTC IC, which would track time and communicate it to the MCU for displaying and other things. I suspect that I would want an accurate crystal to drive the RTC IC if I go this route.
My questions:
A. Do any of the above configurations sound reasonable or particularly poor to anyone else?
B. Does anyone have another suggestion I haven't considered?
C. Any experience with something like this or general comments?
Thanks in advance,
Eric
PS - in case it matters, the primary MCU is a PIC18F45K22
I'm considering my approach to a new appliance controller I want to put together.
The controller is responsible for receiving user inputs, listening to a sensor, and sending a signal to a peripheral actuator (as well as an LCD display).
I've built a controller that does the above tasks, but now want to build an "enhanced" version that includes a clock/timer (in the traditional sense of human timekeeping).
Some configurations I've considered:
#1
I have a feeling that I could do a mediocre to poor job using my MCU internal oscillator with timer driven interrupts that are appropriately prioritized to track time. I think this is fairly poor due to the fact that at times global interrupts will be disabled, and also because temperature and other factors will influence the speed of the internal oscillator.
#2
A slight improvement to #1 might be able to be made by using the same general approach as #1, but driving the MCU (or just TIMER0) with a more accurate external oscillator.
#3
I could shell out for an additional RTC IC, which would track time and communicate it to the MCU for displaying and other things. I suspect that I would want an accurate crystal to drive the RTC IC if I go this route.
My questions:
A. Do any of the above configurations sound reasonable or particularly poor to anyone else?
B. Does anyone have another suggestion I haven't considered?
C. Any experience with something like this or general comments?
Thanks in advance,
Eric
PS - in case it matters, the primary MCU is a PIC18F45K22
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