There are hounds of ways to build this.
Use 12F510 or any of the little 10Fxxx parts.
Use the 32768 watch crystal.
In assembly, build the code to toggle the a out put pin. (10 instructions or less) Then build a kill time loop that takes (32768 * 60 – 10) instructions.
OR
In PBP use the pause instruction.
OR
Set up timer0 and prescaller to role over every 4 seconds. (Fosc/4)/128/256) Every 15 of those toggle the output. You software is looking for timer role over and counts to 15.
OR
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search the www for ideas from Roman Black
http://www.romanblack.com/one_sec.htm