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Forum Index : Microcontroller and PC projects : Analog vs Digital I/O
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pcaffalldavis Senior Member  Joined: 17/10/2011 Location: United StatesPosts: 187 |
I'm trying to understand what the differences of the 20 MM outputs are exactly. Seems like all 20 can be used as digital I/O. Looks like temperature sensors will run on the uppper row or bottom row of 10 pins. Before I define all my pins with soldered jumpers on the PCB I thought I'd better check to make sure what exactly the top 10 pins can do that the bottom 10 can't. And for the life of me, even after researching analog computers on wikipedia I don't understand what the special advantage of analog pins is, nor exactly how to use them. Seems I can run 24 volt relays off of either row, and I think the 16x2 LCD will run off the upper row too, so am I missing something basic? Pete in Hyder We're all here 'cause we're not all there. |
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sparkey Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 819 |
at the point of not really wanting to anser this but have you read the maximite manual and you will see that the pins 10- to 14 can do special functions .....pointless.... technicians do it with least resistance |
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| pcaffalldavis Senior Member Joined: 17/10/2011 Location: United StatesPosts: 187 |
If you don't have anything accurate or helpful to contribute would you please refrain from answering my posts? I've read the manual many times. There is no mention of pins 10-14 being different. 1-10 are different from 11-20 but I could not find any explanation of exactly what these differences mean to the un-initiated. Seems like logic “high/low” can be run on either set of pins, and it appears floating point values like are used in temperature sensors can be handled by either set of pins. So, like I asked originally; What exactly are the benefits of the analog 1-10 pins and how might they best be used? Sparkey need not reply. We're all here 'cause we're not all there. |
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| sparkey Senior Member Joined: 15/06/2011 Location: AustraliaPosts: 819 |
page 20 and page four of the manual ver 2 point seven ...this may help 2011-11-21_030601_pin_volts.pdf technicians do it with least resistance |
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elproducts Senior Member Joined: 19/06/2011 Location: United StatesPosts: 282 |
Analog pin are Analog to Digital converter pins. This means they can be connected to an analog voltage and the software will convert it to a digital value. This allows you to hook up sensors to Maximite and measure variable temperature, voltage, pressure, etc. with the proper sensor connected. Digital pins just sense or drive digitally (on/off, high/low, etc.). All 20 Maximite I/O can be digital but only 1-10 can be analog. www.elproducts.com |
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| mookster1 Regular Member  Joined: 10/06/2011 Location: New ZealandPosts: 81 |
Hi pcaffalldavis! Pins 11-14 are counting pins i.e. they can also act as a frequency counter up to 200kHz (and count pulses over 10ns wide). Those pins are 3.3V and can be used as analogue inputs. Happy to help mookster1 RE your original question about the analogue pins: they have an analogue-digital converter behind them which lets them sample voltages ranging from 0-3.3 volts. The Maximite gives the values of these back as actual voltages (i.e. no conversion from a bit value to actual voltage.) Possible uses include graphing the voltage like an oscilloscope (there's an example program in the downloadable zip of example programs that demonstrates this) and it can be used to measure the frequency of mains voltage (just wrap an insulated wire around an insulated mains cable, connect it to an analogue pin and either frequency-count it or just use the ADC and graph it.) You could also connect a microphone and record sounds (I haven't tried this though.) Capacitance is futile - roll on 2012! |
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| Warpspeed Guru  Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
The history of microcontrollers is a long and interesting one. But very briefly, as devices became much more powerful with more available internal features added, the number of connection pins to the outside world became a severe bottle neck. The solution to this problem is to make many of the connection pins have more than one possible function. It would be very unusual to need to use absolutely every possible available feature of the device, so it is entirely practical to allocate pin functions. A very basic requirement might be that some user applications require more inputs than outputs, or vice versa. Being able to use a particular pin as EITHER an input or an output greatly adds to the usefulness of the device. But it does not stop there. Some pins can also be multi functional and access analog inputs or outputs, internal timers and counters, and have other very specific specialties. When laying out your circuit board you need to first figure out what functions of the microcontroller are needed, and which specific pins have those particular features selectable in software. If you read the application notes for the particular chip, it will tell you exactly what each pin can do, and how to select that function in software. This is a general answer to your question, not a specific answer for the exact chip you are using. Cheers, Tony. |
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| pcaffalldavis Senior Member Joined: 17/10/2011 Location: United StatesPosts: 187 |
Thank you folks. That is helpful. Pete in Hyder We're all here 'cause we're not all there. |
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centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320 |
does this help. Thanks to http://www.hamfield.com.au/ Channels (Pins) Functionality 1-10 Analog Input (3.3V) Digital Output (3.3V) Digital Input (3.3V) Interrupt (low and High) 11-20 Digital Output (3.3V) Digital Input (5V) Open Collector Output (max pull up 5V) Interrupt (low and High) 11-14 Frequency Input Period Input Counting Input Cliff |
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