Simple Minute Timer Project - With a Keypad!!

[dbarry722]

Hi folks..

Came across this little project which may be of use to other forum members as it has the complet circuit code and parts list to ponder over. Its a Simple Minute Timer project which I have actually built and have working

Its at http://www.gooligum.com.au/kits/timer1/timer1.html

Everything does as it says on the tin and kind of does what I'm after but... isn't there always a 'but'

As I am nowhere near proficient at altering the code, Rather that counting down Hours & Minutes, how would the code be altered to display Minutes & Second.

It uses a PIC16F690 chip. Is there an equivalant Picaxe chip or have I just been eating too many of Tesco's Horse burgers and talking jibberish. Ive attached the code he uses. If there is an equivalent chip, is it possible to 'convert' this code to work on a picaxe chip?

I've email David at Gooligum to see if he can be of help.

Regards

Declan

 

[nick12ab]

Since it multiplexes the display, it would be best to use one of the fastest PICAXEs like a PICAXE-28X2.

It should be possible to convert the code but it might just be easier to start over - it isn't difficult.

 

[westaust55]

Rather than modify a PIC based circuit and trying to adjust or work from PIC assembler code, consider starting again with the PICAXE solution. When you consider the circuit as shown has a group of resistors and a few transistors for multiplexing there are options like using a smaller PICAXE and an external 7-seg 4 or 8-digit LED driver chip.

A couple of options for the external chip are the SAA1064 or the MAX7219.
For the SAA1064 have a look at my “Getting started . . .” thread here: http://www.picaxeforum.co.uk/showthread.php?22252-Getting-Started-with-the-SAA1064-i2c-bus-4-Digit-7-Segment-LED-driver-chip

Yet to post an equivalent for the MAX7219. Much of the work done but a recent PC crash has slowed a few things down (luckily all backed up but slow on PC rebuild). However there are some other examples and threads covering the MAX7219 if you care to search.
Using such a chip and maybe even an analogue approach to the keypad with an ADC input you might get away with an 08M2 PICAXE chip as the SAA1064 only needs the two i2c IO pins and the MAX7219 needs 3 outputs. Then one more for an ADC based keypad. Driving the Piezo could be included using a method to use INPUT3 as an output with a FET transistor as per a recent “discovery” thread.

 

[inglewoodpete]

Since it multiplexes the display, it would be best to use one of the fastest PICAXEs like a PICAXE-28X2.

It should be possible to convert the code but it might just be easier to start over - it isn't difficult.

The PIC16F690 is a 20-pin PIC so I'd carefully compare its capabilities with the 20X2. Probably no need for the bigger 28X2 chip. The 20X2 can run just as fast as the 28X2 without the (16MHz) crystal.

 

[dbarry722]

Rather than modify a PIC based circuit and trying to adjust or work from PIC assembler code, consider starting again with the PICAXE solution. When you consider the circuit as shown has a group of resistors and a few transistors for multiplexing there are options like using a smaller PICAXE and an external 7-seg 4 or 8-digit LED driver chip.

A couple of options for the external chip are the SAA1064 or the MAX7219.
For the SAA1064 have a look at my “Getting started . . .” thread here: http://www.picaxeforum.co.uk/showthread.php?22252-Getting-Started-with-the-SAA1064-i2c-bus-4-Digit-7-Segment-LED-driver-chip

Yet to post an equivalent for the MAX7219. Much of the work done but a recent PC crash has slowed a few things down (luckily all backed up but slow on PC rebuild). However there are some other examples and threads covering the MAX7219 if you care to search.
Using such a chip and maybe even an analogue approach to the keypad with an ADC input you might get away with an 08M2 PICAXE chip as the SAA1064 only needs the two i2c IO pins and the MAX7219 needs 3 outputs. Then one more for an ADC based keypad. Driving the Piezo could be included using a method to use INPUT3 as an output with a FET transistor as per a recent “discovery” thread.

Hi westaust55

Just for information, a countdown timer circuit utilising a keypad, 20x2 picaxe and a MAX7219 chip is available in a book called 'Picaxe Microcontroller Projects for the Evil Genius'

Found it a very interesting book.

Declan