3 ms·

I agree, but I would say that for personal projects, I find the difference in price quite irrelevant. What's typically important is how the part fits the applic

I agree, but I would say that for personal projects, I find the difference in price quite irrelevant. What's typically important is how the part fits the application. For example, recently I found that the fumes extractor in the kitchen of the flat I rented failed. The PIC on board got tazed with 10V from a broken PSU. I fixed the PSU (replaced cap and regulator, added TVS diode for protection), but the programming on the PIC was lost. So I found that there is one AVR with matching pinout that I could use in place of the PIC. Thanks to AVRs being so easy to program I could program and test it in an hour or so, and even added some extra features. I do other projects where I need more power (Cortex M3/M4), but AVR is hard to beat where it comes to how quickly you can get simple things going.

mschuster91 9y ago
Out of curiosity: what features did that fumes extractor have?! Mine has just a plain old switch to control the fan in 2 speed modes, and another switch to control the light...
- retSava 9y ago
  I guess the microcontroller controls a fan using PWM with a duty cycle depending on the mode. Even if you could do it with a 555, it's easier to just do it with a microcontroller. It also makes it easier to make changes up until production without changing hardware.
  - lmilcin 9y ago
    No, it controlled it through a Darlington array controlling an array of mechanical relays. The fan has 3 220V AC inputs and selecting the combination of inputs changes the fan speed. I haven't looked inside the fan because it worked correctly. I also didn't want to test it to see how it works so I figured it out by analyzing the PCB. Actually that was quite good idea because the relays seem to be connected in such a way as to only allow valid combination to be sent to the fan even in case of invalid input from the microcontroller. I suspect bad things would happen if I sent incorrect inputs to the fan -- looking at how crappy the board was but at the same time that the person put effort into placing the relays to explicitly disallow invalid combinations of power lines to the fan.
- lmilcin 9y ago
  3 speed modes, light, and some diode indicators. Previously there would be one switch to control light, 3 switches to control speed modes and extra switch that I don't exactly know what it did -- probably it controlled some kind of timer. The 3 switches that controlled modes were 0/1 (change speed to 1 if anything else than 1, turn off if it is currently 1), and 2 and 3 which would turn on 2 and 3 speed mode. I have added a 500ms long press to 0/1 switch which means that whatever is happening it turns off both light and fan at the same time. You don't have to turn off light and fan separately and you don't have to press 0/1 twice to reduce the speed to 1 and then to turn it off. As it was sometimes difficult to figure out which speed it was on without looking at the indicators (on the side and not on the front of the extractor) you never knew you had to press it once or twice which was quite irritating.
  - nerfhammer 9y ago
    now, add a motion sensor so the light comes on when you stand near it and a smoke sensor so that it turns on automatically when you start cooking and stops automatically when all the smoke is clear.
    - lmilcin 9y ago
      The object was to place a new chip into an already existing PCB and then program it to work with the existing parts, switches, and so on.
cjsuk 9y ago
I find the PIC peripherals better. The counter is fully async on the PICs for example which allows you to do very fast (50MHz+) pulse counting. Agree for getting things going though - definitely faster and none of that PICkit crap to deal with.
- lmilcin 9y ago
  Most of the time when I go for AVR it is because ease of use and if I need more from MCU I go for Cortex-M because they are dirt cheap and very powerful and you can always find a part that does what you need. For me there just isn't enough middle ground between 8-bit AVRs and ARM Cortex that would justify learning another platform. I might be biased, as I learned starting with AVRs and then took to Cortex-M3/M4 when my projects outgrew 8-bit. If I started with PIC that would probably be PIC/Cortex-M, but AVR is so much easier on a newb like I was few years ago.
  - vvanders 9y ago
    Yeah, for me I love the AVRs for small things but when I step up to a Cortex I love Cypress' PSoC. You get a mini CPLD and Arm m0/m3 on the same bus which lets you do all sorts of clever things.
    - cjsuk 9y ago
      PSoC dev kit is also extremely cheap!
      - vvanders 9y ago
        Yes! They're incredible little chips. Want 8, 2 bit timers? Sure thing! One large 32bit timer? Done! Having a CPLD to drive your peripherals so that you can reconfigure them is a brilliant idea. The fact that you can drop down to VHDL is an awesome bonus. They've also got some small reconfigurable op-amps built in as well that lets do you really clever things while sleeping.
jacquesm 9y ago
You're a dream tenant. The normal procedure when something that is part of the premises fails is to ask the landlord to replace or fix it.
- lmilcin 9y ago
  That's what I would usually do. I have almost 2 decades of interesting experience as a software dev. I am now learning hardware design so that I can create niche hardware products and use my dev experience as an advantage. I decided to fix it only because I am of the opinion that if I want to act professional in any area I can't shy away from projects like that. If I calculated the time I spent on this I could have easily bought few of these, new, for the time I was not spending on billable hours.
  - crankylinuxuser 9y ago
    It's awesome that you did that :) I know it's one of those compliance issues, but it might be a good idea to have an electrician come out. Last thing a renter wants to see, is bodged together "fire badness". I'm not saying yours is by any means! But sane-ness and law hardly go together :/
    - lmilcin 9y ago
      You would be correct (compliance, responsibility, etc.) but I also know for a fact that the guy guys (I won't call them electricians) that would come to fix stuff would not do better job. My kitchen was completely miswired since the building was built. The ground exchanged with neutral line. I tested the lines and put it back together as it should. There were many complaints from previous tenants but nobody was able to figure out and fix it -- seems so basic but nobody could do it.
      - crankylinuxuser 9y ago
        If I wouldn't know better, it sounds like we live at the same place! I get you - that your work is likely higher quality, and you could claim ignorance if anyone did have a complaint. But yeah, on Sunday, I redid some of our outlets and switches. We live in a trailer, and some of the switches were getting intermittent, and some outlets were loose to the point of turning off stuff if they jiggled. But.. I did find out that 1 outlet in the bathroom, the hallway lights, and 1 wall of the living room were on 1 gang... (sigh). I have my work cut out for me if I actually want to do it right.
filomeno 9y ago
> I agree, but I would say that for personal projects, I find the difference in price quite irrelevant Yes, of course, but it just doesn't look good when the price almost doubled in twelve months, specially when you have better and more powerful micros like the STM32 for less money.
- lmilcin 9y ago
  They are more powerful but to say they are better you have to factor in the ease of use. If you can get both MCUs to do the same thing but one of them takes 1/10th the time to set up then which one is better?
  - filomeno 9y ago
    Sure, with "better" I was talking only about the features. I still prefer the AVRs for the ease of use, but they were as easy to use as today when the price was half it is now :)
    - lmilcin 9y ago
      So what is the price of the chip? If you are hobbyist, your main investment isn't going to be chips. Here in Poland, I can buy 5 ATMEGA 328Ps from Mouser for the price of single cinema ticket. Any investment in time or tools is orders of magnitude more than prices of these parts.
Faaak 9y ago
By pure curiosity: would it be a FRANKE fumes extractor ? I have the same problem with mine.
- lmilcin 9y ago
  It is so cheap that there is no mention of any brand on the extractor. I live in Poland so the chances are very slim.
forkandwait 9y ago
Is there a hacking genre in which one replaces the "brain" (e.g. the microcontroller) and the "neurosystem" (e.g. the wires running to relays controlling power) in already extant machinery? Like this fan? I would love to read about that. Maybe help the right to repair.
- lmilcin 9y ago
  Not sure about replacing. My current project is to design completely new electronics for Rancilio Silvia espresso machine. I know this kind of modding is popular with many people buying a machine with modding already in mind.

mschuster91 9y ago

Out of curiosity: what features did that fumes extractor have?! Mine has just a plain old switch to control the fan in 2 speed modes, and another switch to control the light...

retSava 9y ago
I guess the microcontroller controls a fan using PWM with a duty cycle depending on the mode. Even if you could do it with a 555, it's easier to just do it with a microcontroller. It also makes it easier to make changes up until production without changing hardware.
- lmilcin 9y ago
  No, it controlled it through a Darlington array controlling an array of mechanical relays. The fan has 3 220V AC inputs and selecting the combination of inputs changes the fan speed. I haven't looked inside the fan because it worked correctly. I also didn't want to test it to see how it works so I figured it out by analyzing the PCB. Actually that was quite good idea because the relays seem to be connected in such a way as to only allow valid combination to be sent to the fan even in case of invalid input from the microcontroller. I suspect bad things would happen if I sent incorrect inputs to the fan -- looking at how crappy the board was but at the same time that the person put effort into placing the relays to explicitly disallow invalid combinations of power lines to the fan.
lmilcin 9y ago
3 speed modes, light, and some diode indicators. Previously there would be one switch to control light, 3 switches to control speed modes and extra switch that I don't exactly know what it did -- probably it controlled some kind of timer. The 3 switches that controlled modes were 0/1 (change speed to 1 if anything else than 1, turn off if it is currently 1), and 2 and 3 which would turn on 2 and 3 speed mode. I have added a 500ms long press to 0/1 switch which means that whatever is happening it turns off both light and fan at the same time. You don't have to turn off light and fan separately and you don't have to press 0/1 twice to reduce the speed to 1 and then to turn it off. As it was sometimes difficult to figure out which speed it was on without looking at the indicators (on the side and not on the front of the extractor) you never knew you had to press it once or twice which was quite irritating.
- nerfhammer 9y ago
  now, add a motion sensor so the light comes on when you stand near it and a smoke sensor so that it turns on automatically when you start cooking and stops automatically when all the smoke is clear.
  - lmilcin 9y ago
    The object was to place a new chip into an already existing PCB and then program it to work with the existing parts, switches, and so on.

cjsuk 9y ago

I find the PIC peripherals better. The counter is fully async on the PICs for example which allows you to do very fast (50MHz+) pulse counting. Agree for getting things going though - definitely faster and none of that PICkit crap to deal with.

lmilcin 9y ago
Most of the time when I go for AVR it is because ease of use and if I need more from MCU I go for Cortex-M because they are dirt cheap and very powerful and you can always find a part that does what you need. For me there just isn't enough middle ground between 8-bit AVRs and ARM Cortex that would justify learning another platform. I might be biased, as I learned starting with AVRs and then took to Cortex-M3/M4 when my projects outgrew 8-bit. If I started with PIC that would probably be PIC/Cortex-M, but AVR is so much easier on a newb like I was few years ago.
- vvanders 9y ago
  Yeah, for me I love the AVRs for small things but when I step up to a Cortex I love Cypress' PSoC. You get a mini CPLD and Arm m0/m3 on the same bus which lets you do all sorts of clever things.
  - cjsuk 9y ago
    PSoC dev kit is also extremely cheap!
    - vvanders 9y ago
      Yes! They're incredible little chips. Want 8, 2 bit timers? Sure thing! One large 32bit timer? Done! Having a CPLD to drive your peripherals so that you can reconfigure them is a brilliant idea. The fact that you can drop down to VHDL is an awesome bonus. They've also got some small reconfigurable op-amps built in as well that lets do you really clever things while sleeping.

jacquesm 9y ago

You're a dream tenant. The normal procedure when something that is part of the premises fails is to ask the landlord to replace or fix it.

lmilcin 9y ago
That's what I would usually do. I have almost 2 decades of interesting experience as a software dev. I am now learning hardware design so that I can create niche hardware products and use my dev experience as an advantage. I decided to fix it only because I am of the opinion that if I want to act professional in any area I can't shy away from projects like that. If I calculated the time I spent on this I could have easily bought few of these, new, for the time I was not spending on billable hours.
- crankylinuxuser 9y ago
  It's awesome that you did that :) I know it's one of those compliance issues, but it might be a good idea to have an electrician come out. Last thing a renter wants to see, is bodged together "fire badness". I'm not saying yours is by any means! But sane-ness and law hardly go together :/
  - lmilcin 9y ago
    You would be correct (compliance, responsibility, etc.) but I also know for a fact that the guy guys (I won't call them electricians) that would come to fix stuff would not do better job. My kitchen was completely miswired since the building was built. The ground exchanged with neutral line. I tested the lines and put it back together as it should. There were many complaints from previous tenants but nobody was able to figure out and fix it -- seems so basic but nobody could do it.
    - crankylinuxuser 9y ago
      If I wouldn't know better, it sounds like we live at the same place! I get you - that your work is likely higher quality, and you could claim ignorance if anyone did have a complaint. But yeah, on Sunday, I redid some of our outlets and switches. We live in a trailer, and some of the switches were getting intermittent, and some outlets were loose to the point of turning off stuff if they jiggled. But.. I did find out that 1 outlet in the bathroom, the hallway lights, and 1 wall of the living room were on 1 gang... (sigh). I have my work cut out for me if I actually want to do it right.

filomeno 9y ago

> I agree, but I would say that for personal projects, I find the difference in price quite irrelevant Yes, of course, but it just doesn't look good when the price almost doubled in twelve months, specially when you have better and more powerful micros like the STM32 for less money.

lmilcin 9y ago
They are more powerful but to say they are better you have to factor in the ease of use. If you can get both MCUs to do the same thing but one of them takes 1/10th the time to set up then which one is better?
- filomeno 9y ago
  Sure, with "better" I was talking only about the features. I still prefer the AVRs for the ease of use, but they were as easy to use as today when the price was half it is now :)
  - lmilcin 9y ago
    So what is the price of the chip? If you are hobbyist, your main investment isn't going to be chips. Here in Poland, I can buy 5 ATMEGA 328Ps from Mouser for the price of single cinema ticket. Any investment in time or tools is orders of magnitude more than prices of these parts.

Faaak 9y ago

By pure curiosity: would it be a FRANKE fumes extractor ? I have the same problem with mine.

lmilcin 9y ago
It is so cheap that there is no mention of any brand on the extractor. I live in Poland so the chances are very slim.

forkandwait 9y ago

Is there a hacking genre in which one replaces the "brain" (e.g. the microcontroller) and the "neurosystem" (e.g. the wires running to relays controlling power) in already extant machinery? Like this fan? I would love to read about that. Maybe help the right to repair.

lmilcin 9y ago
Not sure about replacing. My current project is to design completely new electronics for Rancilio Silvia espresso machine. I know this kind of modding is popular with many people buying a machine with modding already in mind.