[time-nuts] TruePosition GPS Receiver

ziggy9+time-nuts at pumpkinbrook.com ziggy9+time-nuts at pumpkinbrook.com
Tue May 9 21:59:26 EDT 2017

Actually, I speculated that 3 and 4 were an additional serial port but I have not observed any data on those pins and I haven’t tried sending data at them. They do not follow J2P3 (rxd). It is J1 pins 7 and 8 that BOTH mirror the data on the J2 pin 2 (txd). Whether they (J1 7 and 8) are tied together or are separate paths I don’t know. But you can overlay the scope traces and watch them all toggle together. They are 3.3v though, so if you go the Arduino route make sure you use the proper flavor - we don’t know if any of this IO is 5v tolerant.


> On May 9, 2017, at 6:00 PM, Ben Hall <kd5byb at gmail.com> wrote:
> On 5/6/2017 8:13 PM, ziggy9+time-nuts at pumpkinbrook.com wrote:
>> A few notes on the GPSDO module:
>> - the 5 pin header near U19, the LM74 temp sensor:
>>     - pin 5 or the third pin in the row closest to U19 is the 12v input (measured). the other 4 are all ground.
>> - the 15 pin header:
>>     - pins 1,2,5,6,9,10,13,14 are all ground
>>     - pins 3 and 4 are 3.3v ttl level, I’m guessing another serial port
>>     - pins 7 and 8 are 3.3v ttl level, and contain the same data as J2 pin 2
>>     - pins 11,12 are 1 pps, 10ms, 5v
> Hi Paul and list,
> When you say "pins 3 and 4 are 3.3v ttl level, and contain the same data as J2 pin 2" does that mean that pins 7 and 8 on on the 15 pin header are the RX/TX pair TTL side of the SIPEX TTL-to-RS232 chip?
> +
> One of the things I was hoping for was to find TTL access to the serial port so I don't have to go Arduino TTL to RS232 off-board and then go back from RS232 with the Sipex chip on the board.
> Have taken a look-see on pins 3 and 4 to see if there is any serial data coming in / going out of there?
> thanks much,
> ben
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