This document describes the current status of the CONTOUR CRISP TPU flight software. The document is maintained in archeological order: the most recent information is at the top.
This software version is under construction. The changes made since version 4 are listed below.
The software was clearing the mirror valid flag after using it, but before telemetering it; the result was that the mirror flag always showed "invalid" in the telemetry. This logic was removed. Gene Heyler.
This software version was uploaded to the spacecraft at KSC on April 29, 2002. The changes made since version 3 are listed below.
What we have been calling mirror side A is actually side B and vice versa. Adjusted the "home offset" calibration parameter to compensate.
This software version was uploaded to the spacecraft at GSFC on April 6, 2002. The changes made since version 2 are listed below.
Changed roll algorithm to be based on commanded attitude, not actual attitude, thereby removing reaction to deadband drifts. Gene Heyler.
Added debug values to filter state slots in telemetry when filter is uninitialized, giving visibility into why the filter is unitialized. Gene Heyler.
Instead of sending G&C the time until closest approach, the time will be encoded. A large value (99998) will indicate a closest approach in the future; a zero value will indicate that the closest approach is now. The zero CA time will be set when the target angle becomes "inbound imaging".
Changed mirror home algorithm from velocity control loop to position and velocity control as for slew. The tricky part is avoiding the step input to the position error when going through the index. This is accomplished by using a modified version of the slew control loop that drives the DAC to zero once the index is seen.
Rounded roll correction to nearest integer degree when LOS angle less than given threshold. Gene Heyler.
Clear "last DAC" value each time the 1 Hz mirror control state machine changes state. Otherwise, in rare instances, old "last DAC" values are fed into the PID algorithm causing a spin up.
This software version was uploaded to the spacecraft at GSFC on February 2, 2002. The changes made since version 1 are listed below.
Time-tag images with the center of the exposure rather than with the end of the exposure.
Instead of taking zoom and pan directions from aim software, set tracking image zoom and pan from uplink commands.
Multipacket dumps had the wrong length in the header and successive packets skipped parts of the dump. This has been fixed.
The software is compiled with a set of reasonable default orbit parameters.
The software was originally configured to allow the TPU to send 1 packet every other second. This is inadequate for the tracking telemetry. Increasing the allowed rate to 1 packet per second solves this in the TPU but moves the problem to the DPU. Turning off the default auto-flush in the DPU allows DPU status to be sent every other second and tracking telemetry to be sent every second and stay within CRISP's one packet per second allocation.
This is the version of software that was delivered to the spacecraft on January 9, 2002.