[minima] Re: band switching
- From: farhanbox@xxxxxxxxx
- To: minima@xxxxxxxxxxxxx
- Date: Mon, 10 Feb 2014 01:32:49 +0000
Dave,
There are other savings too:
1. You don't need a pic programmer.
2. The other 1-of-n decoders go low when selected, so you need additional
circuitry there.
3. In a future narrow band design. The same 10 lines out of the 4017 can switch
10 banpass filters as well! That would mean a 2M to 160 M, multiband unit!
- f
Sent from BlackBerry® on Airtel
-----Original Message-----
From: Dave <dave@xxxxxxxxxx>
Sender: minima-bounce@xxxxxxxxxxxxx
Date: Sun, 09 Feb 2014 14:58:54
To: <minima@xxxxxxxxxxxxx>
Reply-To: minima@xxxxxxxxxxxxx
Subject: [minima] Re: band switching
Steve:
Of course if you use a I2C expander such as the PCF8574, you use 0
additional I/O lines. It connects to the I2C in parallel with the Si570.
Dave - WB6DHW
<http://wb6dhw.com>
On 2/9/2014 2:43 PM, Steve VK2SJA wrote:
>
>> Steve, this uses just two lines.
> Alright. I'll admit it. This muddle headed wombat is still very confused.
>
> 1 x Pin to pulse counter in 4017 decade counter to select band pass filter
> +1 x Pin to reset 4017 decade counter to default known start state
>
> = 2 pins
>
> 2 pins + 1 pin for controlling the low pass filter selection = 3 pins.
>
> vs
>
> 3 pins Binary Coded Decimal (BCD) to control *both* low pass filter
> selection and the output band pass filter selection.
>
> Two different ways to arrive at the same level of control. But is it not
> still 3 pins = 3 pins?
>
> So where are we saving an IO line?
>
> I'm probably being completely daft and missing the flaming obvious but I
> just can't see it.
>
> Help!
>
> 73, Steve.
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