I am currently working with one of the TruePosition GPSDO boards, and having a communication issue.
I have the later Rev C board with the CTS OCXO.
I have the board working fine with the RS232 connected to the 6 pin header.
But I would like to eventually use an Arduino to connect to the board, and not use a PC.
If I connect a USB-TTL board to the 15 pin header to bypass RS232, I can receive data, but not transmit to it.
So, I can't break it out of the boot loop when it powers up.
I am a little concerned that the USB-TTL board may have damaged the TruePosition.
I don't believe those TTL ports can handle more than 3.3v.
I have a CP2102 USB board, but I just found out it was one of the flawed ones that put out 4.2v.
It wouldn't control my uBlox Neo 7M board either.
I corrected that and it now works with the Neo.
But not with the TruePosition.
Can someone else here who has a Rev C TruePosition board take some voltage readings for me to compare??
With nothing connected to the headers, I measure 3.3v on pins 7 and 8, which is the transmit out.
When I measure pins 3 and 4, I measure 1.5v. That is the receive in.
I know that pin 5 on the RS232 header needs grounded for it to work, and if it's grounded, then the TTL doesn't accept commands.
But mine will not accept commands even with pin 5 of the RS232 header open.
I didn't realize that my TTL board was a flawed one, so now I'm concerned I damaged something.
Thanks for any help!