2 other options:
1. Binary coded rotary switches (also available). 3 pull up (or pull
down) resistors required.
2. 3 simple off-on switches with pull up resistors (R) could also be
used to enter the data as binary.
(cheapest solution 3 switches + 3 resistors)
+
R for each bit where
__/ __ is a switch R is a pull up resistor
ground __/ __|____ output
For either of these you could use the output directly instead of using a
74HC148 to decode inputs.
Craig
Peter G. Vavaroutsos wrote:
> If you want to save IOs, you can use a multi pole switch and wire each pole
> as one binary bit. This will save you from adding external logic encoders or
> using one IO per switch position. For instance, if you have 4 switch
> positions, you could use a 2 pole switch and wire each pole to count as a
> binary bit. It usually doesn't cost much more for additional poles are
> larger rotary switches, so this is usually an attractive solution.
> www.digi-key.com also carry som rotary switches where you can set the number
> of positions in the field. There is a ring that you adjust that limits the
> rotational travel.
>
> The latest HAL m5i20 driver code in EMC2 is using an updated FPGA firmware
> image that has the secondary encoder pin out issue fixed. I'm pretty sure
> this change was in at least the last release, if not the last two.
>
> ~petev
>
> -----Original Message-----
> Message: 3
> Date: Sat, 07 Apr 2007 18:45:12 +0300
> From: Anders Wallin <[EMAIL PROTECTED]>
> Subject: Re: [Emc-users] Hardware Feedrate Override Control
> To: "Enhanced Machine Controller (EMC)"
> <emc-users@lists.sourceforge.net>
> Message-ID: <[EMAIL PROTECTED]>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Kasparov, Aram wrote:
>
>> Hello Anders.
>>
>
> Hi Aram,
>
>
>> I have questions about 6 position rotary switch and 4 position rotary
>>
> switch.
>
>> Are they all one-pole type of switches or they need to be multi poles?
>>
>
> I guess 1-pole. There's a common terminal to which I bring +5V, and that
> +5V is then switched to one of the 4 (or 6) outputs. There are pull-down
> resistors on the inputs to make sure they are 0 V when there's no signal
> connected to them
>
>
>> About 4 Pushbuttons switches, are they all momentary type switches
>>
> (normally open)?
>
> Yes. EMC uses 'nist-logic' (for each function: one button for on, one
> for off, and a signal to indicate status) so momentary pushbuttons make
> sense.
>
>
>> How many this electronics devises " I first decode the differential
>>
> signals to
> > single-ended ones using a DS3486
> > <http://www.national.com/pf/DS/DS3486.html> ."
> > do I need?
>
> For one jogwheel that outputs differential signals (+A, -A, +B, -B) you
> need one DS3486 to decode it to single-ended signals, just A and B
> (relative to ground). As described on my blog (see link far below), the
> connection is from the next to last page of:
> http://www.irf.com/technical-info/refdesigns/dg-irmck201.pdf
>
>
>
>> How many this type do I need "6-pos switch is encoded with an SN74HC148
>>
> > http://www.alldatasheet.com/datasheet-pdf/pdf/27887/TI/SN74HC148.html>
> > into a 3-bit value." do I need?
>
> You need one 74HC148 to decode the position of one 6-pos rotary switch
> into a 3-bit code. Note that if you don't need to save pins it might be
> easier to just wire each of the 6 outputs of the switch to separate
> input pins.
>
>
>> Can you also send some diagram of soldering/connecting DS3486 and
>>
> SN74HC148 into
> > the circuit?
>
> See above for the DS3486.
> The 74HC148 is really simple, each of the 6 connections from the 6-pos
> switch go to the inputs, and the three-bit output signal goes to inputs
> on the m5i20.
>
>
>
> Anders
>
> _______________________________
>
>> From: [EMAIL PROTECTED] on behalf of Anders Wallin
>> Sent: Sat 2/24/2007 8:38 AM
>> To: Enhanced Machine Controller (EMC)
>> Subject: Re: [Emc-users] Hardware Feedrate Override Control
>>
>>
>>
>>
>>> Dear All,
>>> I have the current EMC2 2.1.0. and a Mesa 5i20 board. How
>>> can I implement a
>>> hardware FRO control? And while I'm asking questions, can I use the 4th
>>> encoder inputs
>>> for a Handwheel or MPG?
>>>
>> Hi David,
>>
>> I documented some of my jogwheel hardware and HAL code on my blog
>> http://www.anderswallin.net/2006/11/jogging-emc2/
>>
>> adjusting feed override requires halui, but it's quite easy to do.
>>
>> If you have the 5i20 with the 'old' firmware then the secondary hardware
>> encoders are broken (pinouts overlap), but with an MPG there's really no
>> reason to use a hardware encoder counter, the HAL software encoder
>> counter works just fine.
>>
>> Anders
>>
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