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If you are havin problems with code here is some to get you started. I find this method simple and sufficiently accurate for most programs. This routine works by reading the A/D signal 256 times adding the result each time to a running total. With an 8 bit reading you will have a 16 bit result after 256 readings. The most sig. 8 bits of this result is the average input. With this method there is no maths involved apart from a simple addition. If you are using a 10 bit A/D the same method can be used with some mods. If you want you can drop the least sig 2 bits of the 10 bit reading and use the same routine! It depends on the number of quantizing steps you require. You will need 4 working regs count - used to count 256 loops. result - holds your A/D reading (not really necessary you can read it from your A/D reg.) reshi - stores the most significant 8 bits of averaged signal. reslo - stores the least sig 8 bits of averaged signal. clrf count ; first DECFSZ instruction will cause ; this reg to go from 00h to 0FFh Loop call (Your A/D read routine) ; get the reading, store it ; in the reg called result ; in your A/D routine movf result,W ; Copy the reading to W reg addwf reslo,F ; Add it to the LSB reg btfsc STATUS,C ; if overflow occurs inc MSB reg incf reshi,F decfsz count,F ; do it 256 times to get average goto Loop movf reshi,W ; (256 readings)/256 in reshi You're averaged 8 bit reading is now in the reshi reg. Hope this helps. --- In , "burt0072003" <burt007@i...> wrote: > Thank you all for your kind help, this gives me some idea for the > above problem, but when it comes to coding in assembly I am not good. > The problem was, when you have 16 bit resolution, last bits will be > going all over the place because of instability, noise, analoge > voltage not settled etc. so some way of seeing them stable or > changing slowly until it is stabilized. Once stable seeing on lcd a > stable number especially the last digits not changing so much. |
Re: Looking for codes to average adc results
Started by ●February 20, 2004
Reply by ●February 26, 20042004-02-26
Reply by ●February 28, 20042004-02-28
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--- In , Chad Russel <chadrussel@y...> wrote: > Same problem here. So what I did with moving average was to subtract > min from max of buffer. If less than certain value, then stable. > > Chad One simple way to get rid of some of the noise is to delete the min max readings. since it seems you are talking about a 16 bit value, and if you want to stay in 16 bit numbers, another way is to take the average you had and then find out how much your current reading is different. This is averaging the deviation. Then just adding it back to the average to get a new average. This method stops working when you have really noisy signals in the upper end of the range. ie: 4.8 volts or so. To handle that, you can just subtract some value from everything and then add it back in the final stages. Dave |
