Some questions

[Steve Graves]

I am writing code to generate MISB KLV data. First problem, I haven’t been able to get the unit to respond to a poll. The unit first came up in broadcast mode and I was receiving a stream of data, so the data channel works in that direction. I then constructed a batch write to turn off all the broadcast (0x50 followed by 31 0x00) starting at address 0. The broadcast stopped. Now I am trying to poll a register. To use register 0 as an example I am sending

0x73 0x6e 0x70 0x0 0x0 0x1 0x51

No response.

Another example register 0x8a (GPS DATE)

0x73 0x6e 0x70 0x0 0x8a 0x1 0xdb

No response

Have I missed some bit that allows polling?

I have other questions, but I will open another topic.

Steve

[Steve Graves]

I had a programming error. Not sure exactly what it is. I now have a different behavior after moving the line “fcntl(iDev, F_SETFL, FNDELAY);” to a different location (before I set the attributes). Now I am getting the following

Request: 0x73 0x6e 0x70 0x0 0x8a 0x1 0xdb
0x73 0x6e 0x70 0x80 0x8a 0x00 0x00 0x00 0x00 0x02 0x5b Error reading: Resource temporarily unavailable
Error reading: Resource temporarily unavailable

So the GP9 is answering and the port is not responding correctly. The problem is clearly mine to solve. Thank you.

I am still interested in getting verification of my understanding of Euler angles and the MISB specification. I am assuming you have knowledge of this type of application for the GP9. I suspect it is a common use.

Steve

[Steve Graves]

I have found my latest problem. As shown above I have set the port to be non-blocking. The return from a read is not 0 it is -1 when there are no characters available. A common serial programming mistake.

Steve

[CalebModerator]

Hi Steve,

I’m glad that you found the problem. I’ll respond to your other thread shortly.

[Author]

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