Development
Guidance In our existing payload, we use an LTC 1290 which is an 8 channel,12-bit synchronous serial data A/D converter (ADC) . I have a breadboard set up that will already interface the ADC to the parallel port on a PC and some software that drives it. This can be the basis for the ADC function. The setup uses 3 data bits and one handshaking bit of the parallel port leaving 5 data bits and, I think, two handshaking bits for other I/O function via the Parallel Port on the MZ-104. See Timing Diagram. Also, the GPS receiver will interface directly to one of the two RS 232 ports on the MZ-104. This leaves the other RS-232 port available for packet radio for the telemetry downlink and remote control uplink. Except for switching it on and off, the ATV subsystem should not require much of the MZ-104 resources. The attitude control system (ACS) is probably the most demanding function, and after basic flight functionality, would be the top priority. It appears that the kits won't be shipped until Feb 20th or so. As soon as the kit arrives, lets get the development system set up somewhere (and see if it can be distributed to more than one user). 1) We should get the system talking packet. I don't want to use an external packet TNC because of additional cost, mass and power required. AX.25 ain't a gonna stress the MZ-104. 2) Lets get it taking GPS data and relaying it out the packet port. Don't worry about using the APRS format cause I doubt we have very many folks that can receive it at present. 3) Next let's make it work with the ADC via the parallel port, and send readings along with the GPS data out the packet port. At this point we have a basically functional flight controller (FC). 4) By now we should know what kind of Attitude sensor and control system we'll have and can define the I/O to the FC. Once this is accomplished, we'll have the first goal achieved: Stable platform. 5) By this point, we'll understand the solar cells, and have some idea of what the power budget is and can begin the power control and autonomous restart development. Priorities: 1) Basic functionality including sensor management and telemetry downlinking. 2) Attitude Control 3) Power Management and Autonomous restart. I am assuming that the category we'll be judged in will be the "how well do we meet our proposed requirements" category. What we have to achieve by August is a proof of concept so we don't necessarily have to build the flight package, just demonstrate functionality of the system. This should be a pretty achievable goal. Take a look at the diagrams and we'll go from there. Best Regards, Tom - WB3AKD NNNN |
