Using the C94-M8P board

I’m new to the whole RTK stuff and so pardon me not knowing some stuff.
I recently ordered the Evaluation Boards from Ublox and got them finaly to work together. Getting good results with these two boards.
The next step for me was, to integrate one of these boards to my experimental quad, running Arducopter 3.5RC5. And thats were the trouble started.
As i recall you guys are using the same chip from ublox and so i hope you can help me out a bit.
On the board there is already one hm-trp hardwired into the UART stream. In order to get the RCTM corrections it has to be configured for 19200 baudrate. As i read the Pixhawk 1 takes about 38400 as a Baurate for the gps.

So i pulled the pin 20 of the J8 connector high, which means, the hm-trp is shut down. With the chip disabled, I hoped to get the directly to pin 20/21 of the M8P but that looks not to work so far. Pixhawk doesn’t receive any data from the chip. Although i tried the autoconfig and the manual config with the tx/rx connection blocked from the FC to the Board.

Am I missing here something? Is someone smart enough to help me out?

If this is blocked i totally understand it. I could have bought the modules from drotek, but let’s face it… the boards from ublox are pretty cheap so it was a pricing decision for the purpose to just “try out” RTK capability

So long…

Finally figuered it out. Works now


Actually the GPS baudrate has been changed to 115200 on Ardupilot side, did this solve your problem?

The Baudrate was not the big problem i had. You can adjust the expected Baudrate of the Serial Port quite easy in the Arducopter firmware.

The bigger problem was, to get the onboard radio to shut off and make a clean connection to the serial port of the pixhawk. F… DF13 Connectors. Now it is working. Not as clean and simple as your Tiny RTK but, forgive me, much cheaper :wink:

M8P chips are quite expensive, so it is difficult to get volume discounts, we expect the prices to decrease in the future :slight_smile: