[GPS_Standard] VE2ZAZ

[Bert, VE2ZAZ]

Roberto,

You need two transistors to do the trick. One transistor will invert and make the GPS 1 PPS falling edge become the rising edge into the controller. You don't want this. It is the 1 PPS rising edge that must be used and the controller triggers on a rising edge.

Bert, VE2ZAZ

----------------------------------------
> From: rbarrioss at msn.com
> To: ve2zaz at sympatico.ca
> CC: gps_standard at mailman.qth.net
> Subject: RE: VE2ZAZ
> Date: Tue, 8 Jun 2010 15:46:06 +0200
>
> Hi Bert,
>
> You are right, Schmitt Trigger inputs have a 4V minimum voltage requirement
> for Vih. I did not think about the buffer type when checking their
> compatibility...
>
> It is somehow working fine for me, but the proper way to do it would require
> a level converter. Since GPS a controller share a common ground, I think a
> transistor plus two resistors for the high state would work.
>
> Thank you,
> Roberto EB4EQA
>
> -----Original Message-----
> From: Bert, VE2ZAZ [mailto:ve2zaz at sympatico.ca]
> Sent: martes, 08 de junio de 2010 13:46
> To: Roberto Barrios
> Subject: VE2ZAZ
>
> Hi Roberto,
>
> I go by memory here, but I think the minimum-high spec on the TTL input of
> the PIC is 4V. It may work in your case, but I know it did not for some
> other users. You are probably very borderline and your performance may
> degrade over time/temperature.
>
> 73,
>
> Bert, VE2ZAZ
> http://ve2zaz.net
>
> Roberto Barrios wrote:
>> Hi Bob, Bert,
>>
>>
>>
>> I've got one Resolution-T running on my VE2ZAZ standard. The datsheet says
> somewhere it's (3.3V limited) output is TTL compatible. Yes, some interfaces
> are pickier than others, but my PCB from Bert is working fine without
> further modifications.
>>
>>
>>
>> I agree with Bob, this is a fine GPS timing receiver. Better specs,
> smaller, less power-hungry and with much more functionality than the older
> Motorola Oncores. The software for this receiver (DSPMON) from Trimble is
> great, but look for version 1.53, not earlier.
>>
>>
>>
>> Regards,
>>
>> Roberto Eb4EQA
>>
>>
>>> Message: 1
>>> Date: Sun, 6 Jun 2010 20:09:33 +0200
>>> From: "Stig Kristiansen - OZ3XO." 
>>> Subject: [GPS_Standard] preferred GPS
>>> To: 
>>> Message-ID: <33FE5497EB6C4EC7A70EF8E1010971B0 at 3XO>
>>> Content-Type: text/plain; charset="iso-8859-1"
>>>
>>> Hi Bob.
>>>
>>> This 12-Ch GPS is very stabile.
>>> http://www.trimble.com/timing/resolution-t.aspx?dtID=overview
>>> Extremely accurate 1-PPS output, synchronized to GPS or UTC within 15
>>> ns (one sigma)
>>>
>>> Stig - OZ3XO.
>>>
>>>
>>>
>>> ------------------------------
>>>
>>> Message: 2
>>> Date: Mon, 07 Jun 2010 07:59:36 -0400
>>> From: "Bert, VE2ZAZ" 
>>> Subject: [GPS_Standard] VE2ZAZ
>>> To: "Stig Kristiansen - OZ3XO." 
>>> Cc: gps_standard at mailman.qth.net
>>> Message-ID: 
>>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>>
>>> Stig,
>>>
>>> Great GPS, but be careful as it is a 3.3V unit. The 1 PPS is not 5V
>>> TTL compliant. It will not directly drive the PPS inputs of many
>>> controller boards such as mine. You will need to scale up the 1 PPS
>>> using a complementary pair of transistors, for example.
>>>
>>> 73,
>>>
>>> Bert, VE2ZAZ
>>> http://ve2zaz.net
>>>
>>> Stig Kristiansen - OZ3XO. wrote:
>>>> Hi Bob.
>>>>
>>>> This 12-Ch GPS is very stabile.
>>>> http://www.trimble.com/timing/resolution-t.aspx?dtID=overview
>>>> Extremely accurate 1-PPS output, synchronized to GPS or UTC within
>>>> 15 ns (one sigma)
>>>>
>>>> Stig - OZ3XO.
>>>>
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>>>
>>>
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>>>
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>>>
>>> End of GPS_Standard Digest, Vol 35, Issue 3
>>> *******************************************
>>
>>
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