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working with MHX example code

PostPosted: Thu Jul 10, 2008 12:57 am
by whowes
We're trying to run the example code for the MHX radios with the development board but we're having some issues...when the transceiver on the board is configured as a slave and a master is connected to a PC, the slave detects the master (i.e. the RSS leds light up) but the master doesn't see that the slave exists (its RSS leds keep cycling) and of course doesn't receive any data. The radio on the development powers up fine and seems to be running the code and transmitting data (according to the LEDs). When both radios are connected to the PC they don't have any problems talking to each other. We are using the MHX2420 and the code appears to be written with the MHX2400 in mind, but I was under the impression that they were backwards compatible. Do you have any insight into what the problem might be?

Thanks.


Re: working with MHX example code

PostPosted: Thu Jul 10, 2008 1:12 am
by aek
Yes ... assumming that you have demonstrated working Master-to-Slave comms using two MHX-2420s and their little serial adapter boards, the the problem is most likely the greater power draw of the MHX2420 ... what's happening is the MHX-2420 on the Dev Board is powering up, then exceeding the current limit set by R23 (see http://www.cubesatkit.com/docs/datasheet/DS_CSK_FM430_710-00252-C.pdf), and it's being power-cycled by the MAX890L that controls power to the MHX socket.

The solution is to re-program your MHX-2420 (using the AT command set) for a lower power setting (e.g. 10mW). Once you get that working, you can replace R23 on the Dev Board with a 0 Ohm resistor, which will give you 1.2A to the MHX, which is adequate.

IOW, the current limit on the Rev C boards is for the MHX2400, which used less than the MHX2420.

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Re: working with MHX example code

PostPosted: Thu Jul 10, 2008 1:27 am
by whowes
OK, we tried transmitting with a lower power transmit power and it worked. Thanks!

Re: working with MHX example code

PostPosted: Fri Jul 11, 2008 9:36 am
by applewood
Your recommendation below is to re-program the MHX-2420 (using the AT command set) for a lower power setting (e.g. 10mW) and then to replace R23 on the Dev Board with a 0 Ohm resistor.

Is the recommendation the same for the FM430 Flight Module?

Thanks


Re: working with MHX example code

PostPosted: Fri Jul 11, 2008 11:22 am
by aek
Of course. The circuits are identical.

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