 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : Audible Alarm For MM170
| Author | Message | ||||
| Andrew_G Guru  Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi, My BBQ Probe (see here) is progressing well with the probe temperature and timers being shown on a MM170 LCD BackPack. I flash the screen red as the probe approaches the set temperature etc. What I am lacking is an audible alarm. Do any of you have any tried "solutions"? (this will have other applications too). (And yes I know the MM+ can do better). Preferably loud enough and low enough frequency for my aged hearing (and even with adjustable frequency and volume? - either in the circuit or via setup on the LCD). I have tried fixed frequency buzzers (with a trimpot to adjust volume - too high a frequency for my ears) and allegedly PWM controllable ones for Arduino (much too quiet). Many thanks, Andrew |
||||
| BrianP Senior Member  Joined: 30/03/2017 Location: AustraliaPosts: 292 |
You need to cycle through a range of frequency - like police / ambo sirens. You also need an amp to boost the PWM - there are heaps of very small single board / chip possibilities out there, 5-12v powered. You could then use this to drive a piezo sounder thingy - some of these are really loud (you need a passive one, not one of the fixed frequency ones). Also there are small single board police siren emulators - just feed them the volts & away they go. Jaycar or Altronics should have them. Although letting the micro do the PWM would let you choose the best range that suits. B |
||||
| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Brian, Many thanks! I paid my local Jaycar shop a visit and settled on. It is a magic little amplifier that does the trick for me. I also bought a number of passive buzzers to play with and this speaker . Now I can now use the PWM command to get notes etc. All buzzers/speaker are loud enough for an alarm. I might add a trim-pot for volume control. I'd make the following comments about the amplifier: - it is stereo (I only need one channel) - it is really small and inexpensive ~Au$5 - its pinouts are spaced for cable connections, not pins/headers, but I was able to cheat and force the ones I needed to standard headers for breadboard etc. - it has a pin "SW" for "Switch" which, when grounded, turns the amplifier off - I'll use that with touch control for "Mute". Cheers, Andrew |
||||
| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Hi, I've spent an hour or so playing with alarm sounds on my MM170. (The dog doesn't like the high pitched ones.) Here is what I have so far (80:20 rule). '. '. For I = 1 to 50 'Just a loop so you get the idea TimerOld = Timer PWM 2, 300, 10 'PWM 2 (is Pin # 26), Frequency, DutyCycle Do:Loop While Timer < TimerOld + 500 '500 is the duration of the "note" in mS TimerOld = Timer PWM 2, 600, 10 Do:Loop While Timer < TimerOld + 500 Next I PWM 2, STOP 'Otherwise it keeps playing the last "note" '. '. Do any of you have any snippets to suggest? Is there a "Library" of MM sounds or even ditties? (I'm really looking for a bit of friendly competition here . . .) Cheers, Andrew Edited 2019-11-11 15:07 by Andrew_G |
||||
twofingers Guru Joined: 02/06/2014 Location: GermanyPosts: 1673 |
I'm using "bird" and "siren" for a small piezo buzzer: Option explicit Dim T1 'temperature from a DS18B20 Dim j 'loop counter const threshold=22 Do TEMPR START 3, 3 T1= TEMPR(3) Print T1 If T1 <threshold Then For j = 1 To 5 bird 'or siren Next j PWM 2, STOP Print "L" Pause 2000 EndIf Loop Sub bird Local integer f1,f2 For f1 = 440 To 3000 Step 200 PWM 2,f1,50 Pause 10 Next f1 For f2 = f1 To 440 Step -200 PWM 2,f2,50 Pause 10 Next f2 End Sub Sub siren Local integer f1,f2 For f1 = 440 To 3000 Step 20 PWM 2,f1,50 Pause 10 Next f1 For f2 = f1 To 440 Step -20 PWM 2,f2,50 Pause 10 Next f2 End Sub causality ≠correlation ≠coincidence |
||||
| Andrew_G Guru Joined: 18/10/2016 Location: AustraliaPosts: 872 |
Thanks Twofingers, Very good - I will pinch them if I may?? OK Shedders - any other snippets? Your code also helped me understand: - PAUSE actually does pause the execution (I put "PRINT TIMER" before and after and then in a second test removed the Pause - sounded very different). From my reading of the manual I expected the "tone" to not stop but to continue until the next "PWM" command (eg as occurs with a ^C). Hence my clumsy workaround of " Do:Loop While Timer < TimerOld + 500". I'll change to PAUSE from now on. - I don't need a trimpot for adjusting volume - just alter the dutycycle parameter! - TEMPR START to set the precision of the DS18B20 reading (I have, without thinking, been using the default - OK for some applications but not all). Thanks again, Andrew Edited 2019-11-12 11:58 by Andrew_G |
||||
| twofingers Guru Joined: 02/06/2014 Location: GermanyPosts: 1673 |
Hi Andrew, sure, it is posted for that.  I hope, you will get more code snippets. Michael causality ≠correlation ≠coincidence |
||||
Turbo46 Guru Joined: 24/12/2017 Location: AustraliaPosts: 1646 |
You might like to have a look at this post for some sounds. Bill Edit: Another approach could be to write a routine that imitates the Maximite SOUND or TONE commands and pinch some sounds from Maximite games? Edited 2019-11-13 10:34 by Turbo46 Keep safe. Live long and prosper. |
||||
 Print this page |
 |
The Back Shed's forum code is written, and hosted, in Australia. | © JAQ Software 2025 |
