Question about UART output

Q&A forumCategory: QuestionsQuestion about UART output
qcyaob asked 4 years ago
Hi, I have 2 questions about UART output of arduino header.
1. I can’t output UBX format stream from UART. I have succeeded NMEA or RTCM format is output, but only UBX format doesn’t output. I modified UBX-CFG-PRT and UBX-CFG-MSGOUT to output UBX-RAWX. I tried it with baudrate 115200 and 460800.
2. My board don’t output stream from UART1. I have confimed UART2 operates normally with IOREF=3.3V via serial-USB converter.
I attached my reciever config file. I am happy if anyone give me some advice.!AidzfXwz4kDK0n-StVNRpS5-ch4i

2 Answers
clive1 answered 4 years ago
You can get NMEA out of UART2, but not UBX
replied 4 years ago

Thank you for your advice!

Ardusimple Staff answered 4 years ago
Hi qcyaob,
1. UBX protocol is not supported over UART2 in current firmware. We didn’t receive confirmation yet if it will be available in the next firmware.
2. It is indeed strange that you could connect use serial-to-USB converter on UART2 and not on UART1, as these pins are tested during our production test. I’m going to ask you for a few additional checks:

  • Try to swap TX/RX:
    • simpleRTK2B RX2,TX2 are intended to be used to communicate with an XBEE radio. If you were using UART2 with TX2/RX2 in one way, you will have to use UART1 with TX1/RX1 connected the opposite way. It’s a good point to improve our documenation. 
  • I recommend you to return the F9P to default configuration, I checked your configuration file and you have a lot of messages enabled that might reach buffer overflow. With this you will have UART1 at 38’400bps and outputting online NMEA. If you work with UBX, work only with UBX.
  • Double check a firm connection with GND and IOREF.
  • Assuming that you have tried to swap TX1/RX1 as proposed above. TX1 and RX1 are completely independent, it’s very unprobable that both break at the same time. That means that if you can’t receive, you still should be able to send. Try to send a command that activates a new message on USB interface, that you can monitor from the PC.

I leave the status of this question as open, keep us posted with your results.

replied 4 years ago

Thank you for your advice!
I could resolve my problem. I didn’t notice that UART TX&RX is invert between UART1 and UART2.
PC————————————-Ardusimple(PCB Silkscreen)
Serial TX—————————————-RX1
Serial RX—————————————-TX1

Serial TX—————————————-TX2
Serial RX—————————————-RX2

And also I have succeeded to receive NMEA&UBX from UART1 without overflow in bellow setting.

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