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I would like to read an analog voltage and if a certain level is present go to a set of instructions (basically just turn an output high). Right now I'm doing it outside the chip with op amps and an opto isolator and turning it into a high to feed a port. The voltage I'm reading is an audio voltage amplified and rectified and sent to port A bit 0. It would be so much easier and use less hardware if I could just send the audio signal into a port, is this possible, the chip does have a comparator. Do I need to program in C or Assembly to do this, as in designating/configurating a port to be a receiver of something other than a digital high or low? thanks much for any help

Hello,

You could do this in a number of ways.

1) use an analogue pin and in your program simply use an ADC component to sample the pin. Then using a decision icon you can test to see if the return value is over a certain value. If it is then perform your task.

2) use the comparitor to see if the voltage on e 1 pin is over a test voltage. You will need some external hardware here eg a potential divider to provide the reference voltage. Then a couple of lines of C code and you can activate the comparitor peripheral which will set a flag when the test voltage is higher or lower then the reference depending on the configuration. Again you could use a decision to look at the flag.

3) Again using a comparitor you could set up a custom interrupt so that this fires every time there is an event.

I rememer a thread dealing comparators:
http://www.matrixmultimedia.com/mmforum ... 40&p=14655
You could also look there.

Thanks for the quick reply, this chip does not do any ADC but accepts an anologue in on bit 0. So it looks like the coding I have to do will be in configuring the port to read analogue. One thing (among many) I liked about Flowcode was it was not necessary to config the ports in TRISA, it seems this will be an exception, I do not know one lick of anything about C programming, I know a little about Assembly as the data sheets use that, anyway back to C, it looks to me it will only require a few lines to configure, also I could use a little help on setting up a reference voltage to compare for a decision, or would the input voltage be in the form of a variable so I could view what it is and set my thresholds accordingly. I know this is a limited little PIC but I like the size and the challenge. thanks again!
P.S. can you recommend a good easy to understand intro into C language

Hello,

To turn a pin into analogue simply add an ADC component to your program and change the component connections so it is conected to the desired pin.

Using a component macro icon you can call the functions of the ADC to read a sample as a byte or as a 10-bit int.

if you read back the value as a byte then 0 will represent 0v and 255 will represent 5V on a 5V system.

Therefore you can have a decision icon that compares the value to a preset value.

eg

adcin > 128

would follow the yes branch if the adcin variable is over 128 or 2.5V otherwise the no branch would be followed.

If you want to learn C code then why not create your Flowcode program, compile to C and then use the Chip -> View C code menu to view the output C file.

Unfortunatley you cannot do the above with a 12F629 as it does not have the analogue capable inputs. You could instead use the 12F675 device or you can use the compartior hardware. Pages 37 - 39 of the datasheet should be useful for getting the comparitor up and running.

Let me know how you get on.