PI3000 Preliminary Mod Schematic (long)

[Anonymous]

Hello,
I've been thinking of a possible, flexible ,modification for my PI3000.
My idea is still to replace the timing chip CD4017 with something that would let me choose the best pulse timing via software(I think 45uS TX pulse , 15uS target sample 30uS long, 190uS ground sample 30uS long).
Here is a schematic for my modification. This is only a study at the moment.
The mod is based on a PIC16F628 microcontroller.
I choose the 16F628 because it has a built in Uart and in a later development a small serial lcd display could be added for further enancement.
The pic 16F628 is a full TTL chip while the CD4017 is a CMOS chip.
On the PI1000-PI3000 schematic I see that the CD4017 is powered with 8 volts circa that are too much for the PIC16F628 5V TTL chip.
A 7805 power regulator and a 4505 TTL to CMOS converter have been added to the schematic to solve the problem.
I plan to connect the small mod board to the PI3000 with a flat cable.
Any suggestion/idea?
I'll be detecting in the next 4 days since there's the lowest seasonal tide here in Italy and I don't want to miss it. So see you next week.... <img src="/metal/html/tongue.gif" border=0 width=15 height=15 alt=":b">

 

[Anonymous]

Hi,
I certainly may be missing something here but if you are going to dig into the machine that deep, then why would you use the 4017 at all? Connect the PIC to the outputs of the 4017 bypassing its use at all and then you can program the PIC to provide whatever timing you want with no constraints imposed by continuing to utilize the 4017.
Just a thought,
FJ

 

[Anonymous]

Hello,
well , <img src="/metal/html/sad.gif" border=0 width=15 height=15 alt=":sad"> , english is not my first language...
In the schematic you see , the CD4017 shown is just a connector (flat cable) to the original CD4017 , and , obviously, it will be removed. <img src="/metal/html/smile.gif" border=0 width=15 height=15 alt="">
Cheers

 

[Anonymous]

.... and to simulate the 4017 (cmos) you need voltage level conversion by the 4505....

 

[Anonymous]

Nothing wrong with your English, just my ability to read <img src="/metal/html/smile.gif" border=0 width=15 height=15 alt="">
FJ

 

[Anonymous]

Hi Luca,
I find displays can be a real pain, since they usually mean push button menus, and they can be very distracting while you're searching. I find Pots are much faster, a quick glance and you can quickly make the adjustment you need.
So in line with this you could use a 12f675 and multiplex the frequency and Rx delay potentiometers to the A to D. The 12f675 like the 16f628 has internal oscillator, and is available in an SO8 package so you could really squish it down.
Cheers Kev.