Ground Control
Debugging of the RMU firmware and ground station software finally made a great leap forward! The PCB in the rocket mounted unit controls all communication between the experiment and the ground crew as well as calculating an optimum time to eject so that the Tx is not facing the sun relative to the Rx. The PCB has been inherited from SCRAP who inherited it from ISAAC who in turn took much from a previous KTH REXUS team; namely MUSCAT. The PCB contains an FPGA, angular rate sensor, and many components to allow communication and connectivity of sun sensors. The main issue that has been encountered with the RMU PCB is communication to the FFUs. Finally today signals where detected! Irritatingly the issue seemed to simply be faulty internal addresses to the FFUs; why oh why didn’t I start by checking that? So with this working, it is time to look into the ground station software. We started out with MuscatEer and found it worked reasonably well but not perfectly. Certain housekeeping data is not being received, oh no! So Laura and I scratched our heads and wondered what could be the cause. We came up with a plan of reading the raw data on an oscilloscope – not a good idea, way too many ones and zeros to make sense of. The next plan of attack was to pull out the communication signal from the RMU to ground station to a second computer to analyse the signal in hex or ASCII. This worked wonders and we could see that the data was being sent correctly. Here is a taste of what we found (in ASCII) and a table explaining it:
#0 RMU address
40001 1 second since communication start
84 Internal timer value
000000 Padding
C01 Status vector of “110000000001”
01BE000000000001 ADC packet 1
02BE000000000159 ADC packet 2
With this news, my work for tomorrow has been decided; I shall be debugging the ground station software. This does not seem too daunting as we have a good idea of what has to be rectified, fingers crossed for a consistently working ground communication this weekend!
