Re: [Paparazzi-devel] Booz Spektrum AR7000 Satellite Integration Code

[Piotr Esden-Tempski]

On Dec 1, 2010, at 11:58 AM, Friedemann Ludwig wrote:

> Hi,
> I am trying to get the Booz Spektrum Satellite receiver code working with an 
> Atmega8. I ported the code. The UART receive interrupt is heavily called, but 
> I do not receive more than one complete Frame, sometimes not even that, and I 
> am not sure if the received data makes sense. After switching the transmitter 
> on, something is received, but than the loop stucks somewhere in the first 
> bits.
> I am a programmer but do not have much experience with embedded systems, so 
> its quite hard for me to track the error. I try to push some debug output on 
> a LCD display.
> The only thing I can think of is, that the baud rate is not precise enough. 
> Because I am using a 8 Mhz crystal there is a 3.5 % deviation from the 
> receiver's rate. Does anybody have experience with that? Might the baud rate 
> be a reason for not getting a stable connection?
> Regards,
> Friedemann

Yes, it is most likely a baud rate problem. In atmega you want to use some very 
wered frequency external quartz to get closer to the desired baud rates. 
Another problem may be that you are loosing interrupts.

And as Poine pointed out already, why are you struggling with that ancient 
technology. You are constrained by the price of it? You need to spend less then 
$4 on the microcontroller? I appreciate the effort though, getting the spektrum 
code run on an atmega sounds like "fun". :)

Cheers Esden

--
Blog: http://www.esden.net
Projects:
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http://github.org/esden/floss-jtag
http://github.org/esden/summon-arm-toolchain

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