In turn I’ve tried Serial 1 and Serial 2, changing them to option 5 having first changed the GPS port to option 2. Pinouts for each port, specifically Tx and Rx, are the same for each port, but still no GPS showing in MP while the GPS module itself is flashing a fix. So I think I can give up on this mRo R15 
Hi Allan, on all the thousands of possible settings of ardupilot I am not familare with. But there is a small difference between the default GPS Port and the Serial Ports. On the GPS Port is also the second serial I2C port to the compass (SDA / SCL). On the Serial Ports on this pins is the flow control (RTS / CTS). For GPS no flow control is used.
So are you set also flow control and baudrate on the used serial port to the correct values?
Hmmm, no. I left them at default values. Tomorrow I’ll check what values were used on the default GPS port and make sure I configure the serial port(s) the same.
Are you certain you haven’t made the classic RX/TX wiring error? TX on the GPS needs to be connected to RX on the autopilot, and vice versa. I feel like I say this a lot…
Also, only configure one SERIALx_PROTOCOL parameter for GPS. Disable the unused ones.
The Tx/Rx pins are in the same relative positions on the serial ports as they are on the default GPS port, and they’re the same type of socket, so I can be reasonably sure I’ve got it right. And I did only configure one port at a time for GPS.
I’ve just checked a previous param file from this heli and I see that the default baud rate for the GPS port is 38,400 whereas the two serials I tested are 57,600. I’ll re-do the test this afternoon with the correct baud rates.
I’ve just tested again now and, with the correct settings, I still get no GPS response from Serial1. With Serial1 settings put back to default, and the correct GPS settings on Serial2 I do get a GPS response.
So what does that tell you about the health of the board? Would you trust it to fly your heli? My Matek board arrived today, so I’m starting configuring and installing that.
So both the GPS and Serial1 ports are broken?
I’d want to know how and why that happened before I trusted the FC to continue functioning reliably.
Hi Allan,
if there is any doubt on the board I don’t recommend to use it on a flying object.
But from my scientific view it might be interesting to figure out what happend.
There is a small HW difference between the GPS port on one side and the serial port on the other side. The serial ports have additional resistors in line between controller port and connector.
I don’t know what happend (costs) if you send the board back to mRo for analysis.
I think this only will work if the board is relative new and it is a waranty case.
For the price of a postage stamp I’m planning to send it back to mRo so they can do a post-mortem if they want.
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