Angry Badger
Member
Hi,
Best wishes to everyone.
I’ve built a little circuit with an LM35 temperature sensing I.C. The LM35 has a linear output = 10mV/Deg C
When I first built the circuit I used a 1.023V reference for my 18F2420 so every mV increase from the LM35 would increase the A/D conversion result by 1. This could give me 0.1 Deg C resolution for my LCD display. It appeared to work ok apart from the gltiches caused by not having a proper averaging routine although I was going to attend to that later. Anyway, reading another thread on this board I saw somebody point out that the minimum Vref should be 3V but , I think it was Futz, said he used 2.55 successfully so I’ve done that, but tweaked to give 2.56V. But it messed up my conversion resolution.
With 2.56 Vref I can only get 2.5mV resolution – 2.56/1024 = 0.0025v and I can’t properly display any conversions that are not a multiple of 0.0025 because they result in a fractional part.
Any suggestions as to how I can achieve 0.1 Deg resolution using a 2.56V reference and 10 bit conversion?
Hope what I’ve written makes sense!
Thanks in advance for any help.
**broken link removed**
Best wishes to everyone.
I’ve built a little circuit with an LM35 temperature sensing I.C. The LM35 has a linear output = 10mV/Deg C
When I first built the circuit I used a 1.023V reference for my 18F2420 so every mV increase from the LM35 would increase the A/D conversion result by 1. This could give me 0.1 Deg C resolution for my LCD display. It appeared to work ok apart from the gltiches caused by not having a proper averaging routine although I was going to attend to that later. Anyway, reading another thread on this board I saw somebody point out that the minimum Vref should be 3V but , I think it was Futz, said he used 2.55 successfully so I’ve done that, but tweaked to give 2.56V. But it messed up my conversion resolution.
With 2.56 Vref I can only get 2.5mV resolution – 2.56/1024 = 0.0025v and I can’t properly display any conversions that are not a multiple of 0.0025 because they result in a fractional part.
Any suggestions as to how I can achieve 0.1 Deg resolution using a 2.56V reference and 10 bit conversion?
Hope what I’ve written makes sense!
Thanks in advance for any help.
**broken link removed**