[time-nuts] Thunderbolt/Arduino RS232 Interface Issue
celephicus at gmail.com
Wed Jun 3 06:21:04 UTC 2015
You have TX connected to TX? Swap your TX/RX connections and see if the
Tom Harris <celephicus at gmail.com>
On 3 June 2015 at 14:38, Dan Quigley <danq at quigleys.us> wrote:
> I'm integrating an Arduino (Due/Mega have tried both) with a surplus
> Thunderbolt and need some advice.
> The Thunderbolt is a known working unit (supplies 10Mhz to my HPSDR rig)
> and the serial interface works fine between it and a PC. I've read the
> coverage about this kind of integration (and some of the archived
> discussions on this board) and am employing a commercially available
> MAX232-based "shield" (RS232 V2) to handle the level translations. Just
> three lines (RX/TX/GND) are used. The MAX232 circuit is working, reliably
> passing data between the Arduino and a PC.
> With the Thunderbolt is connected to the MAX232 no data passes. Activity
> LEDs on the non-RS232 of the MAX232 circuit show no activity when the
> Thunderbolt is providing data, indicating the MAX232 is not performing the
> intended level translation. I've scoped the RX/TX lines coming from the
> Thunderbolt both when connected to the Arduino and not. There is a
> distinct difference. When disconnected, the pulses are about 10.3v and
> nice, crisp and square. Connected, the pulses are ~50% lower in voltage
> (4.1v) showing an exponential rise in voltage and trace noise.
> I'm pretty much stumped at the moment and wonder if anyone can offer a
> suggestion or thoughts on a direction to take.
> Thanks in advance,
> Dan Quigley (N7HQ)
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